Transcriber’s Notes:

  Underscores “_” before and after a word or phrase indicate _italics_
    in the original text.
  Small capitals have been converted to SOLID capitals.
  Illustrations have been moved so they do not break up paragraphs.
  Old or antiquated spellings have been preserved.
  Typographical errors have been silently corrected.
  The table “TIME REFERENCES IN THE DIVINE COMEDY” on pages 358-366
    has been reformatted from horizontal to vertical in order to
    better fit the 72-column format.
  Footnotes have been separated out from the main text by the use of
    lines above and below, made of hyphens.




[Illustration: DANTE STUDYING. _Frontispiece_

_From a fresco by Luca Signorelli at Orvieto._

    Or vedi insieme l’uno e l’altro polo,
    Le stelle vaghe e lor viaggio torto;
    E vedi ’l veder nostro quanto è corte.
                                _Petrarch._]




             DANTE AND THE

           EARLY ASTRONOMERS

                  BY
               M. A. ORR
          (MRS. JOHN EVERSHED).

    Plainness and clearness without shadow of stain,
    Clearness divine!
    Ye heavens, whose pure dark regions have no sign
    Of languor, though so calm, and though so great
    Are yet untroubled and unpassionate;
    Who, though so noble, share in the world’s toil,
    And though so tasked keep free from dust and soil!

         *       *       *       *       *

                                    You remain
    A world above man’s head, to let him see
    How boundless might his soul’s horizons be,
    How vast, yet of what clear transparency.
                              MATTHEW ARNOLD.

                     London
     GALL AND INGLIS, 31 HENRIETTA ST., W.C.
                _And Edinburgh._

              PRINTED AND BOUND BY
                GALL AND INGLIS,
    NEWINGTON PRINTING AND BOOKBINDING WORKS,
                   EDINBURGH.




PREFACE.


An observatory on a mountain top is an ideal place in which to write
on astronomy and poetry, but it has one drawback: the difficulty of
obtaining books on special subjects. My husband’s criticisms and help
have been invaluable, and of books on modern astronomy there is no
lack; but many others which I have wished to consult I have been unable
to procure, and doubtless there are many more which I ought to have
read, but of whose existence I am ignorant.

This defect has been partly remedied, however, by Mr. Wicksteed’s great
kindness in lending me a number of books on Dante subjects.

I am much indebted to my sister, Miss Orr, who has helped me in
preparing these sheets for the press. The index is mainly her work.

Thanks are also due to several members of the staff of this
observatory: Mr. Sitarama Aiyar made some calculations, Mr. Nagarajan
Aiyar projected the map facing page 295, Mr. Krishna Aiyar prepared
photographs of several illustrations, and Mr. Krishnasawmy typed the
greater part of the copy for press. Mr. Raymond Beazley, the Trustees
of the British Museum, and Messrs Macmillan, have kindly allowed me to
reproduce illustrations from their publications.

To all these I offer grateful thanks.

                                               M. A. EVERSHED.

    KODAIKANAL OBSERVATORY,
         SOUTH INDIA.
             _October 1913._

                               THIS BOOK
                            IS DEDICATED TO
                                 LUCY.




LIST OF PRINCIPAL AUTHORITIES.


    Alfraganus, Elementa Astronomica. Arabicè et Latinè,
          opera Jacobi Golii (Amsterdam, 1669).
    Angelitti, Sulla Data del Viaggio Dantesco.
         ”     Sull’ Anno della Visione Dantesca.
    Antonelli, Sulle Dottrine Astronomiche della Divina Commedia (1865).
    Aratus, The Phainomena. Translation by R. Brown.
    Aristotle, Four Books on the Heavens. Greek and German, with notes,
          by C. Prantl.
    Beazley, Dawn of Modern Geography.
    Berry, History of Astronomy.
    Blake, Astronomical Myths, based on Flammarion’s History of the
          Heavens.
    Boffito et Melzi Eril, Almanach Dantis Aligherii (1908).
    Brunetto Latini, Li Livres dou Trésor. (Chabaille, Paris, 1863).
    Budge, Wallis, Guide to the Babylonian and Assyrian Antiquities,
          British Museum, 1900.
    Cantelli, La Conoscenza dei Tempi nel Viaggio Dantesco.
    Cicero, De Senectute.
       ”    Somnium Scipionis.
    Cornewall Lewis, Historical Survey of the Astronomy of the Ancients.
    Coulton, From St. Francis to Dante.
    Delambre, Histoire de l’Astronomie Ancienne.
        ”     Histoire de l’Astronomie du Moyen Age.
    Della Valle, Il Senso Geografico-Astronomico della Divina Commedia
          (1869).
    Dreyer, Planetary Systems from Thales to Kepler.
    Epping and Strassmeier, Astronomisches aus Babylon.
    Gardner, Dante’s Ten Heavens.
    Gruppe, Die Kosmischen Systeme der Griechen.
    Ideler, Ursprung und Bedeutung der Sternnamen.
    Imbriani, Studi Danteschi.
    King, History of Sumer and Accad.
    Lockyer, Dawn of Astronomy.
    Lubin, Dante e gli Astronomi Italiani.
    Maunder, The Oldest Astronomy. (_Journal of the British
          Astronomical Association_).
    Moore, Dante and his Biographers.
      ”    Studies in Dante. 3 vols.
      ”    Time references in the Divina Commedia.
    Parker, Mrs. Langloh, Australian Fairy Tales.
    Plato, The Republic. Translation by Jowett.
      ”    The Timaeus.       ”           ”
    Plutarch, On the Face in the Moon. Translation by Prickard.
    Pradeau, Key to the Time-Allusions of Dante.
    Rashdall, Universities of Europe in the Middle Ages.
    Ristoro d’Arezzo, Della Composizione del Mondo colle sue Cagioni.
          (Narducci, Milan, 1864).
    Scartazzini, A Companion to Dante, translated by Butler.
         ”       La Divina Commedia (edizione minore, with notes).
    Schaubach, Geschichte der Griechischen Astronomie bis auf
               Eratosthenes.
    Schiaparelli, I precursori di Copernico nell’ Antichità.
          ”       I Primordì dell’ Astronomia Babilonese.
          ”       I Progressi dell’ Astronomia Babilonese.
          ”       L’Astronomia nell’ antico Testamento.
          ”       Le Sfere Omocentriche di Eudosso, di Callipo,
                       e di Aristotile.
          ”       Origine del Sistema Planetario Eliocentrico presso
                       i Greci.
    Temple Classics, Dante, (Divine Comedy, Convivio, Latin Works, with
          translations and notes).
    The Panchasiddhântikâ of Varâha Mihira. Translated from the
           Sanscrit, and edited by Thibaut and M. S. Dvivedi.
    Toynbee, Paget, Articles on Dante’s Obligations to Alfraganus,
             Albertus Magnus, Orosius, and Dante’s theories regarding
             the markings on the Moon (in _Romania_ and _Giornale
             Storico della Letteratura Italiana_).
       ”   Dante Dictionary.
       ”   The Life of Dante (Oxford Biographies).
    Tozer, An English Commentary on Dante’s Divina Commedia.
    Wicksteed, The Early Lives of Dante.
    Wicksteed and Selfe, Villani’s Chronicle.
    Witte, Dante-Forschungen.

       *       *       *       *       *

All quotations from Dante’s works are taken from Moore’s _Tutte le
Opere di Dante Alighieri_, 3rd edition, Oxford 1894.

Astronomical data are chiefly taken from Young’s _Manual of Astronomy_,
and the _Nautical Almanac_.




CONTENTS.


                                                                    PAGE
     INTRODUCTION                                                     1

                                 PART I.

         ASTRONOMY FROM PRIMITIVE TIMES UNTIL THE AGE OF DANTE.

       I. APPARENT MOVEMENTS OF THE HEAVENLY BODIES AS SEEN
           FROM EARTH                                                 9

      II. THE BEGINNINGS OF ASTRONOMY. Gnomons and
             clepsydras; the constellations and the calendar;
             astrology and star-worship; early cosmogonies           25

     III. GREEK ASTRONOMY: FIRST PERIOD.
             B.C. 900 to B.C. 350
          1. Homeric Greece; First Notions of Astronomy              51
          2. Thales and Anaximander: Earth flat, heaven a
             series of hemispheres                                   55
          3. Later Flat Earth Systems: the Universe a sphere         60
          4. Pythagoras and his Followers: Earth round,
             Earth in Motion                                         66

      IV. GREEK ASTRONOMY: SECOND PERIOD,
             B.C. 400 to A.D. 150
          1. Plato: the World-Soul                                   79
          2. Eudoxus: the Spheres                                    88
          3. Calippus: the Spheres of Eudoxus improved               93
          4. Aristotle: the Philosophy of the Spheres; the
             three kinds of motion; Earth immoveable at the
             centre of the Universe; the elements; the
             celestial movers, and the First Mover                   95
          5. Aristarchus: Earth turning on her axis, and
             revolving round the sun                                107
          6. The School of Alexandria: instruments and
             methods; Earth’s diameter measured; the theory
             of Moveable Eccentrics                                 112
          7. Hipparchus: “the Father of Astronomy;” his
             star catalogue; his inventions and discoveries;
             the precession of the equinoxes                        122
          8. Ptolemy: the Almagest; the system of Epicycles
             and Eccentrics; distance and size of the moon
             discovered; the stars; astrology; geography, the
             seven climates                                         134
       V. RETROSPECT: Greek Cosmogonies; Greek calendar             159
      VI. ASTRONOMY UNDER IMPERIAL AND CHRISTIAN ROME.
             B.C. 46 to A.D. 1000. Amateur
             Astronomers; the Julian Calendar; passion for
             Astrology; the Fathers; the ecclesiastical Calendar;
             the Schools; the Monasteries                           167
     VII. ARAB ASTRONOMY. A.D. 750 to 1250.
             Schools of Baghdad, Egypt, Spain. Improvements in
             Mathematics and Instruments; Ptolemy’s values more
             correctly determined; supposed discoveries of
             planetary distances and trepidation; a ninth sphere
             added to Ptolemy’s eight                               181
    VIII. THE RETURN OF GREEK ASTRONOMY TO EUROPE.
             A.D. 1000 to 1300. The Universities;
             Arab influence; Greek books; new European books;
             the course in Astrology in Bologna; Aristotle and
              the Church                                            199

                                PART II.

                         THE ASTRONOMY OF DANTE.

       I. POPULAR ASTRONOMY IN ITALY IN DANTE’S
            TIME. The astronomy of Dante contrasted with
            Homer and Milton. General feeling for astronomy
            in his day; some famous astrologers: astronomy
            considered an ennobling study; Ptolemy’s system
            final. Knowledge of average educated man.               209

      II. DANTE’S STUDIES. Dante a representative of
             contemporary beliefs: his erudition; his
             education; Brunetto Latini’s influence;
             possible visits to universities of Bologna,
             Padua, Paris.                                          223

     III. BOOKS ON ASTRONOMY USED BY DANTE.
             Dante’s wide reading; his diligence and memory.
             Ptolemy his supreme authority on astronomy; his
             principal text-books Alfraganus and Aristotle;
             versions used. Classical Latin authors; Greek;
             Arab; Christian                                        231

      IV. ASTRONOMY IN DANTE’S WRITINGS. References
             to heavenly bodies in Vita Nuova, the Canzoniere,
             Convivio, Latin works and letters, Divine Comedy.
             Artistic use of the facts and theories of astronomy.   253

       V. OBSERVATIONAL ASTRONOMY
           1. Movements of the Moon                                 261
           2. Movements of the Sun                                  270
           3. The Stars                                             283
           4. The Galaxy                                            303
           5. The Planets                                           307
           6. Eclipses                                              316
           7. Comets and Meteors                                    318
           8. The Sun’s Path in the Sky seen from
                different Parts of the Earth                        322
           9. Celestial Phenomena and Time                          338
      VI. DANTE’S JOURNEY THROUGH THE THREE REALMS:
                INDICATIONS OF TIME AND DIRECTION BY
                MEANS OF THE SKIES
           1. Time references in the Divine Comedy                  353
           2. The Inferno                                           367
           3. Purgatory                                             373
           4. Paradise                                              391
           5. Positions of Sun, Moon, and Planets among
                the Stars during Dante’s Vision                     402
           6. The Assumed Date of the Vision                        409
     VII. THEORETICAL AND SPECULATIVE ASTRONOMY
           1. The Spheres                                           429
           2. The Spheres and the four Elements                     441
           3. Dimensions and Physical Nature of the Universe        457
           4. Influence of the Spheres on Human Affairs             471
           5. The Motive Power                                      480
    VIII. MEDIÆVAL AND MODERN VIEWS OF THE UNIVERSE                 487




ILLUSTRATIONS.


                                PART I.
    FIG.                                                            PAGE
       DANTE STUDYING. _From a fresco by
                       Luca Signorelli at Orvieto_        _Frontispiece_
     1. The Sun’s Path in the Sky at different Seasons               11
     2. The Moon at Sunset, soon after New, and three days old       14
     3. Path of Mars among the Stars, 1909                           16
     4. The Star Sphere                                              19
     5. Synodic and Sidereal Periods                                 21
      STAR MAP                                                       34
      THE MOON-GOD OF UR. _From a Cylinder-seal in the British
           Museum, date about_ B.C. 2400.
          _By permission of the Trustees of the British Museum_      36
     6. The triple Star-sign of the Babylonians                      37
     7, 8, 9. The young Moon and the Pleiades after
              sunset, as seen in Babylon, B.C. 1000                  42
    10. The Scorpion. _From a Babylonian boundary stone
         of about_ B.C. 1120, _set up in the reign
         of Nebuchadnezzar I. Now in the British Museum_             43
    11. The Goat with Fishes’ Scales. _From a Babylonian
            boundary stone_                                          43
       THE BOAT OF THE SUN TRAVELLING OVER THE SKY.
           _From an ancient Egyptian papyrus. Reproduced
            from Flammarion’s Astronomical Myths_                    46
    12. The Universe according to Anaximander                        59
    13. The Universe of Leucippus                                    63
    14. The Universe of Democritus                                   64
    15. The Universe of Pythagoras                                   71
    16. The System of Philolaus: night on Earth                      73
    17.      do.      twelve hours later: day on Earth               73
    18. Earth and Sun according to Heraclides                        74
    19. The Spheres of the Sun in the system of Eudoxus              90
    20. Method of Aristarchus for finding the Distance of the Sun   108
    21. Pekin Observatory                                           114
    22. A Pekin Astrolabe of the thirteenth century A.D.
         _From photographs taken in 1888 and published
          in the Bulletin de la Société belge d’Astronomie_         116
    23. The Moveable Eccentric                                      119
    24. The Movement of Spica                                       124
    25. The Sun and the Equinox                                     128
    26. The Movement of the Earth’s Axis which is the true cause
         of Precession. _From Young’s Manual of Astronomy_,
         1902                                                       131
    27. Precession of the Equinoxes                                 133
    28. Path of Mars, 1909                                          139
    29. The Epicycle                                                139
    30. A Planet “retrograding” and “in opposition”                 140
    31. Venus, Mercury, and the Sun                                 142
    32. The Sun’s Deferent                                          145
    33. Apparent Variation in the size of the Sun.
         _Photographs taken at Kodaikanal Observatory,
          with the spectroheliograph, July 1, 1911, and
          Jan. 3, 1912. Actual size of the negative_                146
    34. The Moon’s Epicycle and Deferent                            148
    35. The Ptolemaic System                                        151
    36. Method (erroneous) of estimating Planetary Distances,
         described by Alfraganus                                    188
    37. Earth’s Shadow                                              192

                               PART II.
    FIG.                                                            PAGE

    A MEDIÆVAL ASTRONOMER. _From a painting by Gerard Dow_          200
    ASTRONOMY. _From a fresco in the Spanish Chapel
                of Santa Maria Novella, Florence_                   217
    38. The Half-Moon shape of the Habitable Earth (Ristoro)        247
    CLIMATE MAP OF ABOUT A.D. 1110. _Reproduced from
                 Beazley’s Dawn of Modern Geography_                248
    39. Sun, Moon, and zenith. To illustrate _Par._ xxix 1-6        267
    40. The Zodiac and the Months                                   276
    41. The Ram on the Ecliptic. _From the Cosmi Historia
               of Robert Flud_, A.D. 1612.
              _Reproduced from Brown’s Aratos._                     279
    MAP OF STARS VISIBLE BEFORE DAWN IN PURGATORY                   295
    42. Ursa Minor as a Horn. _Par._ xiii. 10                       299
    43. The Sun at the Equinox, seen from the poles and
               the equator. _Conv._ III. v.                         327
    44. Lunar and Solar Eclipses                                    339
    MAP OF THE WORLD BY HEINRICH OF MAINZ,
          about A.D. 1110. _Reproduced from Beazley’s
          Dawn of Modern Geography_                                 344
    45. The Universe of Dante                                       355
    46. The Signs of the Zodiac at sunrise from the Mountain
          of Purgatory                                              375
    47. Northern Slope of the Mountain of Purgatory                 377
    48. Dante’s View of Earth from the stars. _Par._ xxii.          395
    49.      do.      Six hours later. _Par._ xxvii.                396
    50. An impossible interpretation of _Par._ xxvii.               399
    51. The Rising Sun at the spring equinox. _Par._ i. 39          403
    52. The Moon’s Epicycle and Deferent                            449
    53. Comparative sizes of the Sun and his satellites             490




ABBREVIATED TITLES OF BOOKS USED IN THE TEXT.


    Dante’s Works:—
      _Inf._       Inferno.
      _Purg._      Purgatorio.
      _Par._       Paradiso.
      _Canz._      Canzone.
      _Son._       Sonetto.
      _Ball._      Ballata.
      _Ecl._       Eclogue.
      _V. N._      Vita Nuova.
      _Conv._      Convivio.
      _De Mon._    De Monarchia.
      _V. E._      De Vulgari Eloquentia.
      _Ep._        Epistola.
      _Qu._        Quæstio de Aqua et Terra.

      _El. Ast._         Elementa Astronomica (Alfraganus).
      _Comp. del Mond._  Della Composizione del Mondo (Ristoro).




DANTE AND THE EARLY ASTRONOMERS.




INTRODUCTION.


In a beautiful passage of the _Convivio_ Dante describes how he first
began to devote himself diligently to science and philosophy. When
the gentle soul of Beatrice had passed to heaven, a great darkness
fell upon him: the streets of Florence were to him as a deserted city,
and his life empty and purposeless. It was long before he could find
any comfort, but at last he bethought himself of studying a book by
Boëthius, who when exiled, imprisoned, and unjustly condemned to death,
had strengthened his soul with the “Consolations of Philosophy.” This
led him on to Cicero’s book “On Friendship,” in which Lælius explains
how he is consoled for the death of Scipio.

Books in those days could only be had in manuscript, full of
abbreviations, and often also of errors, and at first the young
student found the Latin hard to master; but as he struggled on,
half deciphering and half divining the meaning, the mists cleared a
little, and the weight was lifted from brain and heart. With elation
he discovered that obscure passages were becoming luminous, and to
the exhilarating sense of conquest was added the joy of finding,
beautifully expressed, thoughts which had already floated in his own
mind, but dimly, as in a dream. He compares himself to one who, seeking
silver, should light (not without Divine guidance) on a treasure of
gold; for he found not only relief from his tears, but a door into a
new world of literature, philosophy, and science. Henceforth, he tells
us, he eagerly frequented the schools of the religious orders and the
discussions of the philosophers; and how extensive and thorough was his
learning we can see in his writings. In them we find a reflection of
thirteenth-century thought in every field of intellectual research.

Among all his studies was one which evidently had a great attraction
for him, even in the early days of the _Vita Nuova_, before learning
had become a passion. Astronomy appealed to many sides of his nature.
The beauty of the skies stirred his imagination; their suggestive
symbolism touched his religious sense; the harmony of the celestial
movements and the accuracy with which they can be foretold delighted
his instinct for order and precision. He must have read, and perhaps
possessed, some of the best text-books then available, and he grasped
with singular clearness the phenomena observed and the theories taught
in his day. His works are full of allusions to astronomy. In the _Vita
Nuova_ he finds pleasure in connecting the story of his lady with the
revolutions of the spheres; in the _Convivio_ he teaches the elements
of the science; in the Vision of the _Divine Comedy_ he journeys
through the universe as it was depicted by mediæval astronomers;
and throughout his works are scattered similes drawn from celestial
phenomena and descriptions of “le belle cose che porta il ciel.”[1]

------------------------------------------------------------------------
[1] “The fair things that Heaven holds.” Inferno XXXIV. 137, 138.
------------------------------------------------------------------------

Therefore, for full enjoyment and understanding of Dante’s works it is
necessary to have a rudimentary knowledge of astronomy.

Many of his readers think that Dante’s astronomy is very complicated
and difficult to understand. What makes it seem difficult is that in
this age we are generally unfamiliar with the skies. We do not eat our
breakfast or go to our office by the sun, nor do we watch the stars
to see when grouse-shooting begins or the summer holidays end. If it
is important for us to know at what hour the sun sets and lamps must
be lighted, or if we wish to see a view by moonlight, we consult an
almanac. When we think at all of the movements of the heavenly bodies,
our notions are usually taken from diagrams and tables, not from what
is actually seen in the skies. We only think, for instance, of the
seasons as caused by the earth’s journey round the sun, and the tilt
of her axis: therefore, when Dante speaks of Venus as a Morning Star
veiling the Fishes with her rays, or the horn of the Celestial Goat
touching the sun, it conveys little, although the seasons of spring
and of winter are as clearly indicated as if he had spoken of the
blossoming of primroses or the fall of snow. When Cacciaguida, in the
heaven of Mars, tells the date of his birth by counting how many times
the planet had since then returned to his Lion, those who only think of
Mars as circling round the Sun, and have never traced his path among
the stars, are at a loss, and think the method very far-fetched. A
short description, and especially a little individual watching, of the
apparent movements of the heavenly bodies, would put us in a position
to realize the meaning of a large number of Dante’s astronomical
descriptions and allusions, without any knowledge of any theory.

Others complain that the subject is dull. Dante’s astronomy, when
interpreted only by means of notes on single passages, is undoubtedly
dull—as dull as the history of his own times learned in the same way.
But when either subject is studied as a whole these passages acquire a
special interest; and they in their turn give new life to the subject
they illustrate.

Other readers say that Dante’s astronomy is so entirely false and
obsolete that it is not worth study. This is hardly true. Where Dante
speaks of appearances he is remarkably accurate, far more so than
most modern artists and writers of fiction. Where he speaks of the
heavens as he supposes them actually to exist, he is interpreting the
appearances according to the astronomical theories of his day, with
which he was very well acquainted. This interpretation was not correct,
but it was an ingenious and beautiful system, and very successful in so
far as it enabled astronomers to calculate the positions of sun, moon,
stars, and planets for any date. Its main outlines can be explained in
a few pages, with the help of a couple of diagrams, but when presented
thus, especially to those unfamiliar with the skies, it seems very
strange and artificial. To appreciate it at its true worth, we must
know just what are the phenomena it was intended to explain, and trace
its gradual development out of man’s first clear perception that the
movements of sun, moon, and stars follow unchanging laws.

The story of this development is of enthralling interest, and after
the system had been completed by one of the greatest mathematicians
the world has seen, its later history reads like a romance. Though of
classical Greek origin, it was almost wholly lost to Europe for many
centuries, it returned at last in Oriental dress, and its final form
was given by a devout and learned Dominican friar.

It was at this time that Dante was born, and the scholar-poet
immortalized the Ptolemaic system of astronomy in his verse, adding
to its popularity in his own day, and making it known to thousands of
readers since, who might otherwise scarcely have heard of it.

Dante’s astronomy, therefore, is of wide and deep significance. To
study its history is to learn a chapter in the development of the
human intellect; to see the universe with his eyes is to know how it
appeared, not only to his contemporaries but to men in many lands and
many centuries. The system of Ptolemy was already a thousand years
old when Dante studied it, and it continued to be taught long after
Copernicus had introduced a truer one; nor has it ever been completely
swept away, for much that it taught was accurate. The new astronomy
has developed from the old, and bears traces to this day, in its
phraseology, its written symbols, and its methods, of the many races
and ages which have contributed to its progress.

This book, therefore, is divided into two parts. In the first, I put
before my readers the elementary facts which form the foundations upon
which all astronomy is based, the movements of sun, moon, stars, and
planets, so far as they can be easily observed by the naked eye; then
follows a sketch of the attempts which were made to interpret these
observations from very early days until Dante’s time. Unnecessary
technicalities are avoided, but we shall try to enter into the thoughts
of past generations concerning the stars, to see why they were
interested, how they worked, what hindered and what helped them in
their search for truth.

In the second part, we shall examine Dante’s works, and see how
familiar he was with the movements of the skies, and how well he
understood the theories which in his time were held to explain them.
We shall see how astronomy was generally regarded in his day, what
books he read, and which authors influenced him most. We shall see how
false is the assertion often made that in the Middle Ages men studied
astronomy only for the sake of astrology, and how closely the science
of the stars was connected with religion and the loftiest speculations
of philosophy.

We shall also examine in particular some difficult passages connected
with astronomy which occur in Dante’s works, but my aim is not so much
to explain all the astronomical references as to put the reader in a
position to attempt an explanation himself.

My greatest ambition is to share with others the pleasure I have had in
learning what Dante knew and thought about the stars, and who were the
master builders who had erected through the ages the system so vividly
pictured in his immortal poem.




_FIRST PART._

    THE STORY OF ASTRONOMY FROM PRIMITIVE TIMES
             UNTIL THE AGE OF DANTE.




I. APPARENT MOVEMENTS OF THE HEAVENLY BODIES AS SEEN FROM EARTH.


The stars appear to us like points of light, differing greatly in
brightness, and scattered very irregularly over the dome above us. All
are moving, some much more quickly than others, yet a little attention
shows that they do not change their relative positions, and therefore
that all must share in one connected movement. If, for instance, any
one group be singled out, and looked for again some hours later, it
will be evident that it has moved considerably as a whole, yet the
stars composing it have kept the same places with regard to one another.

Careful and prolonged observations prove that to observers in the
northern hemisphere one star has hardly any perceptible movement, that
those nearest to it sweep round it in small circles, and those further
away in larger and larger circles, parts of which are hidden below
the horizon. All these circlings are performed in the same time, and
therefore the stars near the stationary point move more slowly in their
small circles than those further away.

All this is precisely what we should see if the sky were a great hollow
sphere, turning about the earth on an axis which runs close to the
almost stationary star—known therefore as the Pole Star. The direction
is from east to west, and a complete revolution is made in a day and
night.

We can plot the stars on a globe, and draw an equator on it, which will
everywhere be at an equal distance from the poles, and we may add other
circles, as on a terrestrial globe: then the position of each star can
be referred to these circles as towns on earth are found by latitude
and longitude, and the path of any moving body, such as a comet, may be
traced.

The stars fade out when the sun rises, but he too sweeps across the
sky as though carried round by the same sphere, and he sets like them,
in the west. Has he a fixed place on the sphere, keeping always the
same position relatively to the stars? No, for in the place where he
has just set we do not always see the same stars. Night after night
those which were clear in the western sky as soon as it was dark enough
to see them, grow closer to him, till at last they are lost in his
twilight beams. Thus the sun, though sharing in the daily east to west
movement, has a slow movement of his own on the sky-sphere, slipping
back from west to east, until in a year he has accomplished the whole
round, and sets again among the same stars.

Moreover, this peculiar movement of the sun is not a mere lagging
behind the stars, for his west to east motion is combined with a north
and south motion. If we note the star-groups which are just behind him
when he sets (or just before him when he rises), we shall find that
they form a great circle round the globe, half of which lies north
and half south of the celestial equator. The Greeks named this circle
the Zodiac, or “Path of the Animals,” because the star-groups forming
it were mostly called by the names of animals (the Ram, Lion, Fishes,
etc.). When the sun is in the most northerly part of the zodiac it is
summer in the northern hemisphere; when he is in the most southerly, it
is summer in the south. (See Map).

[Illustration: Fig. 1. The Sun’s path in the sky at different seasons.]

This north and south motion of the sun may be noted more directly in
another way. Seen from any given place on the earth, each star rises
and sets at the same points of the horizon always, and has the same
course in the sky; but the rising and setting points of the sun,
which on about the 21st of March are due east and west, travel daily
further north, and the sun mounts daily higher in northern skies until
about the 20th of June; then he returns towards the south, passing
the east and west points again about September 23, and reaches his
furthest point south about December 21. (The dates vary slightly
owing to Leap Year). The dates on which the sun reaches his furthest
north and furthest south points in this yearly journey are called the
“solstices,” because his motion seems to be checked, and he pauses or
“stands” before reversing his direction; the dates on which he passes
the midway point are the “equinoxes,” because at those points he is on
the equator, and makes day and night equal all over the earth.

The time taken by the sun to pass from one vernal (spring) equinox to
another is 365 days, 5 hours, 48 minutes, 45 seconds. Since this slow
motion along the zodiac is from west to east, contrary to the rapid
east to west motion which he shares with all the stars, he takes a
little longer to complete a daily revolution than they do; and if we
reckon a solar day as consisting of 24 hours, a “sidereal” (or star)
day is equal to 23 hours, 56 minutes, 4 seconds.

These are very elementary facts, but they are the fundamental facts
of astronomy, and without recollecting and holding them clearly in
mind we cannot understand Dante’s allusions, nor see the fitness of
any astronomical system, ancient or modern. To those who have only
read about astronomy in books, and have not watched the skies, they
may be puzzling, and I would beg these readers to make a few simple
observations for themselves, as this will help them more than any
written explanation can ever do to see the heavens with Dante’s eyes.
To appreciate the connected movement of the whole sky, some bright
stars near the Pole should first be watched, such as the Great Bear
and Cassiopeia, or for those in the southern hemisphere the Southern
Cross, Canopus, Achernar. Their motions should be compared with those
of bright stars near the equator, such as Orion, Virgo, or Aquila. The
constellations of the zodiac should be studied, and notes made of the
seasons at which each disappears in the rays of the sun.

The sun’s north and south movements can be easily recognized by noting
at what points of the horizon he rises or sets at different times of
the year; and the different heights to which he rises in the sky are
most simply observed by marking the length of the shadow of some tree
or pole at midday. Or if some rough kind of gnomon[2] be made, even
a flat piece of wood, laid on a sunny window-sill, with a long nail
driven vertically into it, the movement and varying length of the
shadow, from hour to hour, and from day to day, will make one realize
vividly the diurnal and the seasonal movement of the sun. This device,
in one form or another, was probably the first astronomical instrument
invented, and by its means ancient astronomers in many lands solved
important problems.

------------------------------------------------------------------------
[2] Greek _gnomon_, an interpreter. A pole set up in order to show the
length of shadow thrown by the sun.
------------------------------------------------------------------------

It is not necessary to explain that the daily apparent movements are
caused in reality by the earth’s rotation on her axis, and the yearly
apparent movements by her revolution round the sun. These are the
book-learned facts which for the most part obscure our perception of
the very things on which they are based. I would ask the reader to do
his best, for the moment, to forget them.

The movements of the moon among the stars are much more easily observed
than those of the sun, since we can see the stars at the same time, and
her revolution is much more rapid. She also is apparently carried round
with the daily east to west movement, and she also has a west to east
motion of her own, but so fast that it takes her round the star sphere
in one month, instead of one year. This revolution also takes place in
the zodiac. She is first visible as a fine crescent, just following
the sun, in the west, after he has set; next night she is markedly
further from the sun, on her eastward course, and is a larger crescent;
she continues increasing her distance from the sun and the size of her
disc, until, as full moon, she is rising in the east when the sun sets
opposite her in the west, and setting when the sun rises. After this,
she begins to wane, and, still travelling in the same direction, rises
later and later at night, and sets in the day; she draws gradually
nearer to the sun on the western side, till at last, as a fine crescent
with the horns turned in the other direction (_i.e._ always away from
the sun), she appears just before the rising sun in the east. Then for
a short time she is lost in his rays, till she emerges as a new moon on
the sunset side again.

[Illustration: Fig. 2. The Moon at Sunset.]

The moon completes a revolution among the stars in 27 days, 8 hours;
but it takes her a little longer to come up with the sun again, since
he has meanwhile been moving in the same direction along his yearly
path; and the ‘synodic’ month, or period from one new moon to the next,
is 29 days, 13 hours.

As well as the moving sun and the moving moon, there are five other
bodies, visible to the naked eye, which move among the stars. They look
like stars, but their movements would lead us rather to class them with
sun and moon. They also are in the zodiac, and they also, while carried
round with the universal movement from east to west, revolve slowly,
each in its own period, from west to east. But their motions are more
complicated than those of sun and moon. Two, which we call Venus and
Mercury, are never seen very far from the sun, and they oscillate
from side to side, sometimes appearing before him near sunrise, and
sometimes after him at sunset. Mercury keeps closest to the sun, and is
not so bright, and therefore less easy to see; but Venus is a brilliant
object when she gradually swings out further from the sun, remaining
longer each evening after sunset in the western sky. Then she gradually
draws back, closer to the sun, is lost in his rays, and a few days
after begins to appear on his other side, as a Morning Star, visible in
the east before sunrise. Here she swings out again, like a pendulum, to
her furthest distance west, and then draws in again, just as she did on
the sunset side of the sun.

In this way, swinging slowly from side to side of the sun, Mercury and
Venus make with him the circuit of the zodiac, completing a revolution
from west to east in about a year. The average period of Mercury’s
oscillation, counting, for instance, from one Greatest Western
Elongation (_i.e._ furthest distance from the sun on the west) to the
next, is 116 days; that of Venus is 584 days.

[Illustration: Fig. 3. The Path of Mars among the Stars, 1909.]

The other three “wandering stars”—or “planets,”[3] as they were named
by the ancient Greeks—Mars, Jupiter and Saturn, are also often seen as
morning or evening stars near the sun, but they do not always accompany
him, like Venus and Mercury. They may be seen at any distance from
him, even exactly opposite, so that they rise as he sets. They keep as
strictly to the zodiac, however, and travel in it from west to east, in
periods of approximately two, twelve, and thirty years respectively;
and their paths are also complicated by oscillations. Periodically
they slacken speed, stop, and go back a little distance among the
stars, then they slacken, stop, and advance again. These changes are
technically called direct motion, stations or stationary points, and
retrograde motion.

------------------------------------------------------------------------
[3] Greek _planetes_, a wanderer. This name was originally given to
Mercury, Venus, Mars, Jupiter, Saturn, and also to sun and moon, for
it indicated all the known heavenly bodies which changed their places
among the stars. In modern usage it is not applied to the sun, but only
to his satellites, of which many more are now known.
------------------------------------------------------------------------

It must have originally taken many years of patient watching to
discover and distinguish all these planets. In these days, by means of
an almanac and some knowledge of the constellations, they may easily be
found and traced. Mars and Venus move quickly during part of the time
they are visible, and if sketches be made of their positions among the
stars, and their paths marked for a few weeks, a very good idea may be
gained of the motions of planets as seen in the skies.

Once again, it is not necessary to explain here that these movements
of the planets are due partly to their revolution round the sun, and
partly to the Earth’s motion. Nor need we, for our present purpose,
consider them in any detail: all that is important to realize is the
general character of the movements, and their likeness to those of sun
and moon.

The distances, and therefore the sizes, of all the heavenly bodies are
completely beyond measurement, except with instruments and refined
methods; their physical nature could only be guessed at before the
discoveries of universal gravitation and spectrum analysis, in the 17th
and 19th centuries of our era. All that can be observed by naked eye
astronomy is difference of brightness and colour; as for instance the
contrast between ruddy Mars and white Jupiter; the steadier light of
all the planets as compared with stars; and the interesting fact that
the moon shines by reflected sunlight, which is made evident by the
connection between her phases and her position with regard to the sun.
Her surface, too, is clearly seen to be diversified by dark markings of
definite shape, but on no other body in all the sky can we make out the
least detail without a telescope.

The movements of the heavenly bodies, therefore, which still form one
of the most important parts of astronomy, were almost all that could be
studied by ancient astronomers, and gave them the only key they had to
the problems of the universe.

To sum up:—The chief apparent movements of the heavens, visible to the
naked eye, are eight, viz:—

The daily revolution of the entire heavens, carrying with it every
visible celestial body, in a little less than 24 hours; the revolutions
of sun, moon, and five naked eye planets, in seven different periods.

The first of these is from east to west, and is by far the most rapid.
The axis of revolution passes through two points which we call the
celestial poles, and the motion is parallel to the celestial equator.

All the others are in the main from west to east, though the progress
of the planets is complicated by periodical retrograde movements. All
take place in the zodiac, which is a series of constellations forming
a great band round the heavens. The path of the sun is a great circle
through this, called the Ecliptic (because eclipses can only happen
when the moon is also on it); and the paths of moon and planets are
slightly and variously inclined to it.

Thus the daily path of a star is affected only by the simple uniform
movement of the entire heaven (in reality the rotation of the Earth)
but the daily path of a planet, or of the sun or moon, results from a
combination of this general movement with its own peculiar movement,
which is generally in the opposite direction.

[Illustration: Fig. 4. The star sphere.]

If it is difficult to conceive a body moving simultaneously in two
different directions, an earthly analogy will make it easy. On a great
moving platform, such as that which encircled the Paris Exhibition in
1900, there are fixed posts etc. which revolve exactly as the whole
platform revolves and do not move about amongst themselves. These are
like the fixed stars on the (apparently) revolving sphere. But human
beings are free to add their own movements to that given them by the
platform on which they stand. One man turns his back and walks steadily
and very slowly in the opposite direction, and so he neutralizes part
of the platform movement and is not carried onward quite so quickly
as the stationary posts: he is the sun. A woman walks as he does, but
much more quickly, so that she rapidly passes many posts, although all
the time she is being carried backwards with them: she is the moon.
Children run backwards and forwards: they are the planets. Finally,
if all these people are also constantly crossing the platform slowly
from right to left and back again, their movements will be oblique to
the platform movement and will imitate the north and south movements of
sun, moon, and planets.

It is in this fashion that the movements of the skies present
themselves to careful observers on this seemingly stationary earth; and
in the youth of the world these apparent movements were believed to be
real. The ancients thought that the sky was actually revolving round a
steadfast earth, while the sun and moon and certain other “wandering
stars” had in addition various motions peculiar to themselves.

The table of periods which follows (see pp. 22-23) will be found useful
for occasional reference. Some of the terms used will be explained
later.

[Illustration: Fig. 5. Diagram illustrating Synodic and Sidereal
Periods.

    The arrows show the direction of the Moon’s monthly
    and the Sun’s yearly revolutions in the zodiac, as
    seen from Earth.

    When the Moon is opposite the Sun, for instance in
    Libra while he is in Aries, she is full. In 27½
    days she returns to the same place among the stars,
    and this is a SIDEREAL MONTH. But the Sun
    meanwhile has moved into Taurus, and not until the
    Moon has reached Scorpio, opposite to him, will
    she be full again, and complete her SYNODIC
    MONTH (29½ days).]

                 REVOLUTIONS OF SUN, MOON, AND PLANETS
                        AS SEEN FROM THE EARTH.

                                             _Days.  Hrs.  Mins.  Secs._
    Tropical Solar Year: period from one
       vernal equinox to another, or from
       one summer solstice to the next, &c.   365     5     48     45·5
       (Our civil year is based on this).
    Sidereal Year: period between two
       successive returns of the sun to any
       star on his path                       365     6      9      8·9
    The difference between these two kinds of year is due to Precession
    of the Equinoxes, _vide infra_, p. 23.

                                             _Days. Hrs. Mins. Secs._
    Solar Day: period between two successive
       passages of the sun across
       the meridian (noon)                     —     24      0      0
    Sidereal Day: period between two
       successive passages of a star across
       the meridian                            —     23     56      4
    The difference between these two kinds of day is due to lag of the
    sun behind the stars, his daily motion westward being slightly
    retarded by his slow yearly motion eastward.

                                             _Days. Hrs. Mins. Secs._
    Mean Synodic Month: period between
        two full moons                         29    12     44      2·8

    Mean Sidereal Month: period between
        two successive returns of moon to
        any star on her path                   27     7     43     11·5
    The difference between these two kinds of months is due to the fact
    that while the moon is making her revolution among the stars, the
    sun is also moving slowly on in the same direction.

                                             _Days. Hrs. Mins. Secs._
    Mean Anomalistic Month: period
        between perigee and perigee
       (_vide infra_)                          27    13     18     37·4

        PLANETS:—Mean Synodic Revolution: period
            between two successive conjunctions with the sun,
            and mean zodiacal revolution: period of revolution
            round the zodiac.

                  _Mean Synodic Revolution.   Mean Zodiacal Revolution._
        Mercury          116 Days[4]                 1·0  Years
        Venus            584  ”                      1·0    ”
        Mars             780  ”                      1·88   ”
        Jupiter          399  ”                     11·86   ”
        Saturn           348  ”                     29·46   ”

------------------------------------------------------------------------
    [4] Fractions omitted.
------------------------------------------------------------------------

        PRECESSION OF EQUINOXES: 50·25 seconds of arc
            in one year; that is, 360 degrees (a revolution
            among the stars of the zodiac) in 25,800 years
            nearly.




_II. THE BEGINNINGS OF ASTRONOMY._


                             Note.

    As these pages are passing through the press,
    a letter from Mr. Maunder appears in _The
    Observatory_ for August 1913 on “The Origin of
    the Constellations,” and this should be consulted
    by anyone interested in the subject. Mr. Maunder
    points out that Ptolemy gives us much more precise
    information than Aratus regarding the southern
    limits of the ancient constellations, and that the
    changes which he says he ventured to make in their
    traditional forms are extremely insignificant.

    Mr. Maunder further observes that the celestial
    equator of Aratus cannot give any clue to the
    origin of the constellations (as R. Brown
    suggested), but only to the date of the work from
    which Aratus copied, when some astronomer had drawn
    the equator through the constellations. A slight
    alteration of the text, Mr. Maunder says, would
    give a correct equator for the date B.C.
    1000.

    See also Mr. and Mrs. Maunder’s article in _Monthly
    Notices of the Royal Astronomical Society_ for
    March 1904.

    Proctor’s “Origin of the Constellation Figures” is
    in his book _Myths and Marvels of Astronomy_.




II. THE BEGINNINGS OF ASTRONOMY.


The sky appears to us like an arch, embracing all our lives, Dante
says.[5] From the dawn of intelligence man must have recognized his
dependence upon the all-embracing heavens, especially the sun, without
which life would be impossible. The consciousness expressed itself in
many ways: in adoration of the sky, the sun, moon, and hosts of heaven;
in superstitious fear which regarded events on earth as directly
controlled by the heavenly bodies; in careful watching and recording of
their movements for useful purposes. Thus, long before astronomy became
an exact science, and was studied simply for its own sake, patient
observers had laid the foundations, and were familiar with many of the
movements we have been describing.

------------------------------------------------------------------------
[5] Conv. IV., xxiii. 56, 57.
------------------------------------------------------------------------

These are of great importance to primitive man. Sun, moon, and stars
are invaluable as guides, especially at sea, and we know that the
ancient Greek mariners used to steer their ships by observations of the
Great Bear, while the Phoenicians preferred to use the Little Bear for
this purpose. But the strongest and most universal incentive to careful
and prolonged study of the skies is our complete dependence upon them
for the measurement of time.

In the earliest period of their history, the Jews, the Greeks, and
probably every other nation, divided the day simply into morning,
noon, and evening, according as the sun was rising, or apparently
stationary, or sinking, with regard to the horizon; and the passage
of some bright stars indicated the time at night. But at a very early
period the first of all astronomical instruments was invented, by which
the sun’s varying height can be measured: hence the time of noon, the
dates of equinoxes and solstices, and the length of the solar year
can be determined. The gnomon in its simplest form is a pole set up
vertically on a smooth level surface, on which its shadow as cast by
the sun can be observed. The moment of shortest shadow marks the middle
of the day, the shortest midday shadow marks the summer solstice,
the longest the winter solstice, the equinoxes falling between. The
instrument also indicates the points of the compass, for the sun is
always due south in northern latitudes at midday: hence the Latin word
_meridies_ (French _midi_) means south as well as midday, and the
Meridian in astronomy is a line which passes through the north and
south points and the zenith, and is crossed by the sun at midday.

The gnomon was said to have been introduced into Greece by Anaximander
about 600 B.C., and the Babylonians claimed to be the inventors, but
it was probably invented independently by several races. The Chinese
certainly observed the length of the shadow more than two thousand
years B.C., and the very interesting fact has recently come to light
that a tribe in a hitherto unexplored part of Borneo use such an
instrument, invented by themselves. They set up a post about 6 ft.
high, and throw over the top a piece of string weighted at each end to
show when it is vertical; the length of the shadow cast by the post is
measured with a notched stick. By this means they tell the time of
day; and they also observe the sun (presumably with the gnomon) to know
the right season for planting their rice.[6]

------------------------------------------------------------------------
[6] Dr. C. Hose, in “Travel and Exploration,” for Feb. 1910, quoted in
“Nature,” Feb. 17, 1910.
------------------------------------------------------------------------

However rough the first gnomon may have been, its importance can
scarcely be overrated, for it introduced measurement and calculation
into observation of the sun’s movements, and it is the ancestor of our
modern sextants, transit telescopes, and other instruments of precision.

It was also the beginning of the sundial. The course followed by the
moving end of the shadow was traced on the ground, and divided into
equal parts: hence arose the custom which the Greeks adopted from
the Babylonians of counting twelve hours in every day, from sunrise
to sunset, and twelve hours in every night, from sunset to sunrise,
regardless of the varying lengths of day and night at different
seasons. This is known as the system of “temporary hours.” If we used
it in England, the twelve hours of a midsummer day would take twice as
long to pass as the twelve fleeting hours of a midsummer night; but in
Greece the inequality is much less, and in the latitudes of Babylonia
it is never striking. The skill and knowledge of the Greeks enabled
them, later on, to construct dials of different kinds, which marked
“equal hours,” such as we use now; but the system of “temporary hours”
did not altogether die out till after the invention of pendulum clocks
in the 17th century of our era.

Clepsydras, or water-clocks, were also used in Egypt and Babylonia,
and ancient Greece; and there is still a large one in Canton, where
a reservoir is placed in a tower, and the water falling, drop by
drop, into a receiver whose depth is marked in figures on the wall,
indicates the passing of time just as sand does in running through an
hour-glass. These clocks cannot have kept very good time, however, or
they would have been more used by the Babylonian and Greek astronomers
who took pains to ascertain the exact positions of the stars. Owing to
the diurnal revolution of the skies, the time at which any celestial
body rises or crosses the meridian after another is an index of their
distance apart, east and west on the sphere, and this is how it is
reckoned by modern astronomers. But the ancients seem to have been
never able to trust their clepsydras sufficiently to use this method,
and only referred to them for approximate time.

The gnomon, valuable as it is for marking the sun’s daily course, and
the north and south part of his yearly motion, is a limited instrument.
It cannot show his westerly motion on the sphere, nor is it of any use
for the planets. To trace these motions, and the monthly journey of
the moon, the first step is to distinguish the stars, by grouping and
naming them, especially those which lie in the path of sun, moon, and
planets. The invention of some kind of zodiac is probably older even
than the invention of the gnomon, and also originated independently
among different races. The germ of the idea may be found to-day among
races low in the scale of civilization. The Australian aborigines are
familiar with that unique star-cluster which we call the Pleiades,
and know that its appearances and disappearances are periodical and
coincide with the seasons. A Queensland tribe, for instance, has
a legend in which the stars figure as six sisters who have been
transported to the skies, and it is said that they sometimes appear
before the sun in order to throw down icicles, an evident allusion
to the fact that the Pleiades begin to appear just before sunrise in
May, the Australian winter. The natives of Tahiti divide their year
into “Matarii i nia” and “Matarii i raro,” which means Pleiades Above
and Pleiades Below (_i.e._ the horizon at the beginning of night). Sir
Norman Lockyer has shown that the mysterious alignments of stones found
at Stonehenge, Carnac, and other places, may have been so arranged
in order to show the direction, some of the sun at his rising on
certain dates, notably the morning of the summer solstice, and some
of the Pleiades or other striking stars, whose rising just before the
sun would enable ancient astronomers to fix the dates of important
festivals.

Such observations as these, of which many instances might be drawn from
many parts of the world, are first steps towards studying the whole
path of the sun through the stars, and of forming a calendar with a
name or number for every day in the year. Until the stars are known,
and a calendar fixed, the motions of sun and moon cannot be learned
in detail, the planets can scarcely be distinguished from the stars
and from one another, and there are no settled dates from which to
calculate their periods.

The first zodiac of which we have written record is a lunar one of
28 constellations, which is referred to in the “Canon of the Emperor
Yaou,” a Chinese emperor who began to reign in B.C. 2356. “Yaou
commanded He and Ho, in reverend accordance with their observation
of the wide heavens, to calculate and delineate the movements and
appearances of the sun, the moon, the stars, and the zodiacal spaces,
and so to deliver respectfully the seasons to the people.” That these
astronomers studied “the movements and appearances” of the sun by
means of the gnomon as well as observations of the stars is plain from
what follows, where directions are given for determining the solstices.
One astronomer was commanded by the Emperor to “reside at Nankeaou and
arrange the transformations of the summer, and respectfully to observe
the extreme limit of the shadow. The day, he said, is at its longest,
and the star is _Ho_: you may thus exactly determine midsummer.” _Ho_
(= fire) is the fiery red Antares in Scorpio. The star of the winter
solstice, when “the day is at its shortest” was Maou, which is the
Pleiades. Directions are also given for observing the spring and autumn
equinoxes, when day and night are of medium length, and certain other
stars are to be observed.[7]

------------------------------------------------------------------------
[7] Journal of the British Astronomical Association, June 24, 1909,
report of a lecture on Chinese astronomy by E. B. Knobel, F.R.A.S.
------------------------------------------------------------------------

The Hindus had also a lunar Zodiac, but with only 27 constellations,
and the Arabs had their 28 “Mansions of the Moon.” These 27 or 28
asterisms were evidently suggested by the moon’s sidereal period of 27¼
days. But her synodical period, _i.e._ her revolution with regard to
the sun, in which she runs through her phases, is much more convenient
for marking a period of time for general uses, and this month of about
30 days has been almost universally adopted by primitive peoples, the
first day being counted when the crescent new moon begins to be seen
after sunset. From this custom arose another, that of counting the
beginning of the day from sunset, but in various times and places other
starting-points have been chosen—sunrise, midday, or midnight.

Twelve of these synodical lunar months are nearly equal to one solar
year, and this doubtless suggested the solar zodiac of twelve
constellations, each constellation marking the portion of sky passed
over by the sun in a month. The Chinese “Yellow Path of the Sun”
contained twelve animals, the Mouse, Cow, Tiger, Rabbit, Dragon,
Serpent, Horse, Ram, Ape, Hen, Dog, and Pig. These animals were widely
adopted by other nations—the Koreans and the Japanese, the Mongols of
Tibet, the Tartars, and the Turks.

Another zodiac, however, was destined to have an even wider popularity,
spreading, in the course of centuries, from Greece to Arabia,
Persia, India, and China, where it finally superseded the native
constellations; it crossed the Mediterranean into Africa, conquered the
whole of Europe, and is used to-day over the whole civilised world.

The names of these twelve zodiacal constellations are familiar to us
all:—

    _English Names.     Latin Names._
         Ram               Aries
         Bull              Taurus
         Twins             Gemini
         Crab              Cancer
         Lion              Leo
         Virgin            Virgo
         Scales            Libra
         Scorpion          Scorpio
         Archer            Sagittarius
         Capricorn         Capricornus
         Water-Bearer      Aquarius
         Fishes            Pisces.

Strange to say, we cannot tell with any certainty where, when, or by
whom, this ancient series of constellations was devised and named. The
earliest full description which we possess is by a Greek poet of the
4th century B.C., Aratus. A line from the prologue to his “Phenomena”
was quoted by St. Paul in his address to the Athenians on Mars’ Hill.

    “From Zeus we lead the strain, he whom mankind
     Ne’er leave unhymned; of Zeus all public ways,
     All haunts of men are full, and full the sea
     And harbours; and of Zeus all stand in need.
     We are his offspring;[8] and he, mild to man,
     Gives favouring signs and rouses us to toil,
     Calling to mind life’s wants; when clods are best
     For plough and mattock, when the time is ripe
     For planting vines and sowing seeds he tells.
     Since he himself hath fixed in heaven these signs,
     The stars dividing; and throughout the year
     Stars he provides to indicate to men
     The seasons’ course, that all things duly grow.”[9]

------------------------------------------------------------------------
[8] Acts, xvii. 28.

[9] _The Phainomena of Aratos, done into English verse by Robert
Brown_, lines 1-13.
------------------------------------------------------------------------

But Aratus did not know who had invented the names of the star-groups
which he describes. “Some man of yore,” he supposes,

    “A nomenclature thought of and devised,
     And forms sufficient found. For men could not
     Or tell or learn the separate names of all,
     Since everywhere are many, size and tint
     Of multitudes the same, but all are drawn around.
     So thought he good to make the stellar groups,
     That each by other lying orderly,
     They might display their forms. And thus the stars
     At once took names and rise familiar now.”[10]

------------------------------------------------------------------------
[10] _Ibid._, 373-382.
------------------------------------------------------------------------

It is, to say the least, exceedingly doubtful, whether the naming of
star-groups was so promptly carried out by one individual, especially
as Aratus’ poem includes, besides the twelve zodiacal constellations,
thirty-six others, which contain all the bright stars of the sky
except those too far south to be seen in the temperate regions of
our northern hemisphere. The spaces thus left blank were afterwards
filled up, chiefly in the 17th and 18th centuries of our era, and the
regions round the South Pole are now crowded with a mixture of birds
and scientific instruments; but the names and the figures of the
traditional forty-eight constellations still find undisputed places on
our globes and star-maps.

Some of these figures are very strange and suggestive. We have a maiden
with wings, a centaur shooting arrows, a flying horse, a water-snake
with a crow and a cup on its back, a charioteer with a goat on his
shoulder, a man strangling a serpent, another pouring water into the
mouth of a fish, and a strange beast like a goat with a fish’s tail.
All had their meaning, doubtless, to their originators, but to us
they are cryptic characters, hard to decipher. Among the zodiacal
constellations only one is obvious, Libra the Scales, the sign in which
the sun is when days and nights are perfectly balanced in length; but
this is comparatively recent, for Aratus and his contemporaries give
in its place the Claws of the Scorpion, the latter being an enormous
monster extending over the space of two asterisms. The figures may have
been religious symbols, or an illustration of some myth concerning
the sun’s yearly course, or each of the twelve may have indicated the
weather or the occupation suitable to the month it represented. The
ear of corn in the hand of the Virgin, and the juxtaposition of three
watery figures in Capricornus, Aquarius, and Pisces, suggest the latter
explanation. Many different ideas probably played a part in the origin
of these mysterious constellation-forms. The Greeks, and after them the
Romans, when adopting the old constellations, sometimes adopted also
the old myths which still clung about them; sometimes they ascribed
legends to them from their own mythology. Thus, the kneeling figure
with his foot upon a dragon, became and remains the hero Hercules,
although Aratus only describes him as a man toiling at some unknown
task, and says he is called simply the Kneeler. Successive generations
of astronomers altered some of the figures, but probably only to a
slight extent.[11]

------------------------------------------------------------------------
[11] Ptolemy says he made a few changes, as his predecessors had done.
(Delambre, _Histoire de l’Astronomie Ancienne_, ii. 261).
------------------------------------------------------------------------

The poem of Aratus enjoyed an immense popularity in classical times
and throughout the Middle Ages, and no doubt helped to stereotype the
forms whose origin was already forgotten when he wrote. He was not
an astronomer, however, and the poem is only a popular paraphrase of
a lost work by Eudoxus. This Greek astronomer had lived a hundred
years earlier, and it is thought that he himself copied from an older
source. The attempt to discover this source has been the object of
many ingenious conjectures, and much research among ancient monuments
and writings. Some of the old constellations are met with in Isaiah
and Job, in Homer, on tablets found at Nineveh, and an immense
antiquity is sometimes claimed for them. Dupuis, writing at the end of
the eighteenth century, thought he had conclusively proved that the
figures of the zodiac were designed in Egypt 15,000 years ago![12] Miss
Plunkett, in her “Ancient Calendars and Constellations” assigns them to
the seventh millenium before Christ.

------------------------------------------------------------------------
[12] _Origine de tous les cultes, ou Religion universelle_, by C. F.
Dupuis.
------------------------------------------------------------------------

[Illustration: THE OLD CONSTELLATION FIGURES.

SOUTHERN HEMISPHERE.]

[Illustration: NORTHERN HEMISPHERE.

THE OLD CONSTELLATION FIGURES ACCORDING TO ARATUS.

_In Ptolemy’s Catalogue Equuleus and Corona Australis are added to
these._

_(From Peck’s “Constellations and How to Find Them.”)_]

An ingenious theory, suggested independently by Schwartz and Proctor,
and developed by Mr. E. W. Maunder,[13] is founded on an examination
of the space round the South Pole which was left blank by the ancient
constellation designers. From its extent, Proctor concluded that they
cannot have seen further south than about 40° from the South Pole, and
therefore that they must have lived in a latitude of about 40° north of
the equator (say, central Asia or Asia Minor); from the position of its
centre, which must have been the Pole, he concluded that the date was
about B.C. 2200. For the centre of the circular patch seems to lie near
the star _Delta Hydri_, which was the South Pole star at that time.
(This movement of the Pole among the stars, due to “precession,” will
be explained later). This date does not differ much from that found
by Robert Brown, from the position of the celestial equator among the
stars, as described by Aratus; he says B.C. 2084.[14] Schwartz gave
B.C. 1400; Mr. Maunder, from additional considerations of the positions
of various constellation figures, says that they must all have been
originally designed about B.C. 2800.

------------------------------------------------------------------------
[13] _Journal of the British Astronomical Association_, “The Oldest
Astronomy,” July 1898, June 1899, April 1904, May 1909; _The
Observatory_, December 1898; _Knowledge_, October 1904; and elsewhere.

[14] _The Phainomena of Aratos_, by Robert Brown. See also his
_Eridanus, River and Constellation_; _Primitive Constellations_, and
other works.
------------------------------------------------------------------------

Unfortunately the descriptions of Aratus are neither very
precise nor consistent with one another, and he is our oldest and
our main authority for the forms and positions of the ancient
constellations.[15] It may, however, be taken as practically certain
that they had been designed many centuries before he wrote, and that
the Greeks received them from the Babylonians. Orion and the Pleiades,
the Great Bear and Arcturus, and perhaps many others, were familiarly
known in the Levant as early as the tenth century before Christ; and we
find traces of our zodiac, or its beginnings, in Babylonia at least as
early as the eleventh. It is always to Egyptians and Babylonians that
the Greeks referred as their predecessors and teachers in astronomy,
but the native constellations of Egypt seem to have been different, and
so far as we know at present the Babylonians began earlier and made
greater progress in star-lore than any other nation before Greece.
The latest results of expert investigation of astronomical tablets
discovered in the ancient clay libraries of Babylonia and Assyria,
tend to show that astronomy was of native growth there, and developed
very slowly.[16] Star-worship and the need for a calendar led their
inhabitants to observe the skies thousands of years ago; but their
early work was naturally vague and rude.

------------------------------------------------------------------------
[15] We are not sure what limits Aratus intended to set in the south
to Centaur and Argo, and notably to the River Eridanus, which used to
flow beneath the Sea-Monster (Cetus), joining the Water poured out
by Aquarius. It changed its bed (like the Euphrates, of which it is
perhaps the heavenly counterpart), and now has left the Sea-Monster
high and dry, while on its ancient banks a chemist’s furnace and a
sculptor’s workshop have been set up.

The Celestial Equator of Aratus fails to agree with the Equator of B.C.
2084, not only in passing over the head of Orion, instead of through
his belt, as Brown himself points out, but also in running through
the eye of the Bull, instead of his “crouching legs alone,” so this
part is altogether too far north. The Equator some 1200 years later
agreed better here, and equally well elsewhere, except in the opposite
part of the sky where it was then too northerly for Aratus, leaving
Corvus to the south of the line. Much the same may be said about the
tropical circles. Either Aratus was careless, or the globe from which
he took his descriptions was incorrect: in any case, there results an
uncertainty of many centuries and many degrees in date and latitude.

[16] Epping and Strassmeier, _Astronomisches aus Babylon_, Kugler’s
_Babylonische Mondrechnung_, and _Babylonische Sternkunde_.
Schiaparelli’s two monographs on Babylonian Astronomy, from which much
of the information here given is derived, are chiefly based on these
works.
------------------------------------------------------------------------

This star-worship and star-study seems to have been learned by the
Semitic Babylonians, and their descendants and rivals the Assyrians,
from a race with whom they met and mingled in the grey dawn of history,
but whose existence was unknown to us before the middle of last
century.

[Illustration: The Moon-God of Ur. [_To face p. 36._

From a cylinder-seal in the British Museum, dated about B.C. 2400.

Reproduced by permission of the Trustees.]

[Illustration: Fig. 6. The triple star-sign of the Babylonians.]

This people, who belonged to a totally distinct family of nations, and
are known to us now as Sumerians, had settled near the mouth of the
Persian Gulf, when it ran further inland than it does now, and more
than five thousand years ago used a kind of writing on soft stones
(later, on bricks) which had obviously arisen from some form of picture
writing, and ultimately developed into cuneiform. Their reverence
for the heavenly bodies is shown by the fact that the familiar star
sign, [star sign] which appears on very early Sumerian inscriptions,
denotes their word for god or lord, and on the monuments of Babylonia
and Assyria we meet constantly the triple sign This, we learn from
the inscriptions, stood for three great deities, the Moon-god, the
Sun-god, and the goddess of the planet Venus. Our illustration shows an
inscription in early Babylonian script, and a scene which represents
the vassal of a king of Ur (Abraham’s “Ur of the Chaldees”) being
led into the presence of the Moon-god.[17] It is believed to date
from about B.C. 2400. The Babylonians were an intensely superstitious
people, and a large part of their omens were drawn from observations of
the skies. Every city from this period onward had its ziggurat or great
tower formed of several superimposed cubes, usually seven in number,
diminishing in size and probably crowned by the shrine of the local
deity. It is not certain what purposes were served by these towers,
but the successive platforms may well have been the observatories from
which the Babylonian priests, gazing through the clear air and over
the level plains, watched, year after year, and century after century,
eclipses of sun and moon, risings and settings of stars and planets,
and all the changing pageant of the skies, which to them were eloquent
of peace and prosperity, or of war and misfortunes in their land.

------------------------------------------------------------------------
[17] King, History of Sumer and Akkad, p. 246.
------------------------------------------------------------------------

Although this illusory art chiefly occupied the early Babylonian
astronomers, they made some observations of real value, and gradually
acquired true knowledge concerning the movements of the heavenly bodies.

Tablets a few centuries older than the Chinese _Canon of Yaou_
containing lists of the Sumerian names of twelve months, show that
this people had established a luni-solar year. Fortunately for the
progress of astronomy the year does not contain an exact number of
months, or even of days: at the end of twelve lunar months, a few
more days and hours must elapse before the sun has returned to his
original place among the stars, and before the round of the seasons is
completed. Therefore the first rough approximation had to be constantly
corrected if calendar festivals were to recur at the same seasons; and
thus the priests, who in early times were usually the calendar makers
and keepers, became gradually better and better acquainted with the
movements of sun and moon, and the appearance of star-groups. It is
interesting to compare the different ways in which various races have
solved the problem of calendar-formation.

The Chinese had a year of twelve months, and added an intercalary month
occasionally, in such a way that the average length of the year was
brought up to 366 days. The written character for “intercalary” in
both Chinese and Japanese is a compound of the characters for “gate”
and “Emperor,” because in ancient days the Emperor used to perform the
ceremonies proper to each of the twelve months in the special room of
his palace dedicated to that month, but in the intercalary month he
performed them in the doorway of the palace.

The Egyptians and the Arabs seem to have given up the attempt to
harmonize the two periods, though both of these nations reckoned twelve
months in their years. The Egyptians counted thirty days to each month,
and added five days more at the end of the twelfth, so that the months
can have had no connection with the moon: the year had, in fact, been
calculated from the position of the sun among the stars, beginning
with the morning on which Sirius rose just before it. This “heliacal
rising” of Sirius heralded the great event of their year, the overflow
of the Nile. The Arab year, on the contrary, was purely lunar, for
it consisted of twelve months which were alternately of twenty-nine
and thirty days: they therefore corresponded pretty closely with the
moon’s phases, but had no connection with the sun or the seasons. The
Mahomedans still use this lunar year.

The new moon festivals of the Hebrews prove that the moon was important
to their calendar, but the three chief feasts of First-fruits, of
Ingathering, and of the Passover, were so closely connected with
the seasons that their year must have been luni-solar. It consisted
of twelve months, one of which was sometimes doubled, but how they
decided when this was necessary is nowhere described in the Old
Testament. Some think, that as an offering of first-fruits was to be
made on a certain day of a certain month, the month preceding it was
doubled in every year in which it was evident that the crops would
not be far enough advanced for the first-fruits to be gathered so
soon: in this way no direct observations had to be made of the sun’s
movements, but the year was accommodated to them by observations of the
seasons.[18]

------------------------------------------------------------------------
[18] Schiaparelli, _L’ Astronomia nell’ Antico Testamento_, chap. vii.;
Wellhausen, _History of Israel_, chap. iii.
------------------------------------------------------------------------

The Babylonian calendar is the most interesting of all, for it was the
most intimately connected with star-observation. At first an extra
month seems to have been added to the usual twelve, in an irregular
way, whenever found necessary, judging by a tablet of the great king
Hammurabi, who united all the cities of southern Babylonia under one
rule, and gave them the famous Code of Laws, communicated to him by the
Sun-god. The tablet runs as follows:—

    “Thus saith Hammurabi: the year having gone wrong,
    let the coming month be registered by the name of
    Ululu the second. And instead of the payment of
    taxes being made on the 25th day of Tasritsu, let
    it be made on the 25th day of Ululu the second.”

Hammurabi reigned about B.C. 2200. A thousand years or more after
this, we find that royal decrees for correcting the calendar were
never necessary, for the astronomers had invented more than one system
for keeping the year right. One of these was to observe, like the
Egyptians, the heliacal rising of certain stars. The little group of
three stars in the head of the Ram, which we call Alpha, Beta, and
Gamma Arietis, was found very convenient for this purpose. When it
rose just before the sun in the month Nisan, the observers knew that
all the twelve months would fall in their right seasons, but when it
remained invisible (hidden in the morning twilight) until the following
month, the calendar was evidently running ahead of the sun, and that
year was lengthened by adding a thirteenth month. This is the meaning
of the directions given on a tablet now in the British Museum:—

    “The asterism Dilgan[19] rises heliacally in the
    month of Nisan. Whenever this asterism remains
    invisible, let its month be forgotten,”

------------------------------------------------------------------------
[19] Sayce and Bosanquet identify Dilgan with Capella, not with
part of Aries, and consider that a date of about B.C. 2000 is
indicated—(_Monthly Notices_ xxxix, 454). But in any case the method of
calendar formation is the same.
------------------------------------------------------------------------

that is, let it be taken over again, as if it had not already been
counted. Similar directions are given for some other asterisms and
their corresponding months. But a second method, which was peculiar,
so far as we know, to the Babylonians, was that of using the moon as
a pointer to indicate the place of the sun. Whereas the sun’s place
among the stars can only be inferred, the moon’s can be plainly seen,
and her phase indicates her distance from the sun at any time. A tablet
of unknown date, belonging to the last millenium before our era, or a
little earlier, gives the following directions:—

    “When on the first day of the month of Nisan the
    asterism Mulmul (the Pleiades)[20] and the Moon are
    seen together, the year will be normal. When on the
    third day of Nisan the asterism Mulmul and the Moon
    are together, the year will be full” (that is, will
    contain 13 months).

------------------------------------------------------------------------
[20] Sayce and Bosanquet understand Capella here also.
------------------------------------------------------------------------

Each Babylonian month began when the new moon was first visible after
sunset; if at this moment she was seen with the Pleiades, it is clear
that the sun, which had just set, was not far west of the cluster; if
however, it was not till the moon was three days old that she was seen
with the Pleiades, she would then be some distance above the horizon at
sunset: consequently the sun was some distance west of the Pleiades.
In this case he would also be west of Dilgan, the Ram’s Head, so those
stars would rise after him in the morning, and be hidden in his light:
therefore, both the morning and the evening observation combined to
show that his course was not completed, and that the year must be
lengthened by the addition of an extra month.

[Illustration: Fig. 7. First Year, normal. New Moon near the Pleiades
after sunset on the 1st of Nisan.

    The position of the young moon (which always
    closely follows the sun) showed that the sun was
    not far west of the Pleiades; and about 1000
    B.C. this proved that it was near the
    vernal equinox. The sun’s position is given for
    about half an hour after sunset, when the Pleiades
    would first be visible.]

[Illustration: Fig. 8. Second Year, normal. New Moon not far from
Pleiades on the 1st of Nisan.

    It takes the sun 365 days to return to the same
    place among the stars, but the Babylonian year of
    12 lunar months (each of 29 or 30 days) was 11 days
    short of this: therefore on the 1st of Nisan in
    this year the sun had still 11 days’ march before
    him ere he returned to the position of Fig. 7. This
    is equal to about 11°, so the young moon was also
    about 11° west of her former position, near the
    Pleiades. But as she travels about 13° eastward
    every day, she would be near the Pleiades on the
    following evening, the 2nd of Nisan, so this year
    was also counted normal.]

[Illustration: Fig. 9. Third Year, “full.” New Moon distant from the
Pleiades on the 1st of Nisan.

    The sun is now 2 × 11 = 22 days’ march, or about
    22°, short of his first position, and the young
    moon consequently about 22° west of the Pleiades,
    so she will not come up with them until the 3rd
    Nisan, after travelling 2 × 13 = 26°. The year was
    therefore “full,” that is an extra month of 29 days
    was added, which is more than the 22 days needed to
    enable the sun to reach his first position by the
    1st of Nisan in the fourth year.

    It appears, therefore, that the extra month must
    have been added once in three or four years.]

Several lists of stars and star-groups indicating the months in this
way have been found, the early lists containing only a few, the later
twelve. If our zodiac originated with the Babylonians, there is little
doubt the idea took its rise from these monthly stars, but it is not
possible, with our present knowledge, to say when these old astronomers
first linked the isolated stars into a continuous series of twelve
star-groups and connected the idea of the month with the invisible
group among which the sun was known to be shining, instead of with the
stars seen east or west of him, or in conjunction with the crescent
moon.[21]

------------------------------------------------------------------------
[21] If Taurus was originally considered the first constellation of
the zodiac, instead of Aries, of which there are some indications, the
change may well be explained by this change of method. It does not
necessarily imply that the equinox was in Taurus when our zodiac was
invented. It was near ω Arietis in B.C. 1000.
------------------------------------------------------------------------

[Illustration: Fig. 10. The Scorpion.

From a boundary stone (now in the British Museum) set up in the reign
of Nebuchadnezzar I., king of Babylonia, about 1100 B.C.]

[Illustration: Fig. 11. The Goat, with Fishes’ Scales.

From a Babylonian boundary stone.]

A Scorpion with immense claws, and a Goat with fishes’ scales appear
several times on monuments at least as old as 1000 B.C. and it is very
probable, although this fact alone would not prove it, that they were
then used as constellation figures. It has been definitely proved from
inscriptions that before 600 B.C. the name of Scorpion was applied to
some stars of our present Scorpion, that there was a Lion corresponding
with ours, and the principal star in that asterism, which was called
“The King” by Greeks and Romans (Basiliskos and Regulus), bore a name
with the same meaning in Babylonia; the Celestial Bull seems to have
been the group of the Hyades, and the Great Twins were the two stars
Castor and Pollux. The last two identifications seem to show how the
single stars or small groups of the monthly lists were expanded into
the large zodiacal constellations, for the Hyades cluster is in our
present Bull, and Castor and Pollux are in our Twins.

Under the great Assyrian kings who in the 8th and 7th centuries
B.C. made Nineveh the capital of their empire, Babylonian astronomy
flourished exceedingly, and it made much progress through all the
political changes which followed, until the beginning of our era.
The motions, phases, and eclipses of the moon were carefully studied
and could be accurately predicted, the positions of many stars were
determined; the zodiac was divided into twelve equal spaces, which
afterwards became 36 by sub-division (the constellations being too
unequal in size for convenience); and finally the whole circle was
marked out in 360 degrees. The movements of all the naked eye planets
were well understood, their positions being constantly compared with
those of a number of standard stars, mostly in the zodiac; and after
watching and recording these for a number of years the astronomers
were able to calculate where each planet would be found at future
dates. Tables have been found on clay tablets of the 2nd century B.C.
predicting the heliacal risings and settings, and the stations and
retrogressions etc., with considerable accuracy.

When astronomy had reached this stage of accurate prediction, it was
no longer in its infancy, but was fairly on its way to become a true
science.[22]

------------------------------------------------------------------------
[22] A Babylonian treatise on astronomy recently published by the
trustees of the British Museum supports Kugler’s view that truly
scientific methods were not adopted before the sixth century B.C. This
treatise formed the subject of a lecture given by Mr L. W. King before
the Society of Biblical Archæology on Feb. 19, 1913.
------------------------------------------------------------------------

Nevertheless, the astronomy of the Babylonians, advanced as it was,
seems never to have progressed beyond the empirical stage. With them,
there seems to have been no desire to group the facts they so patiently
and skilfully collected into a system, and form a theory to explain
them.

And this must be said of other ancient nations also. The Egyptians made
careful observations, especially of the heliacal risings of different
stars, by means of which they determined the length of the year, as we
have already mentioned, and oriented their temples and pyramids. They
worshipped the sun in all his aspects, and their astrology so much
resembles the Babylonian that it is believed to have been derived from
it. The Babylonians seem to have been more interested in the planets
than any other nation of antiquity, but they were known also in other
countries. The Chinese recorded comets, and all races were greatly
interested in eclipses, which they were able to predict with some
accuracy, having discovered that they occur in cycles. Yet we find no
more rational attempt to explain these phenomena than the Hindu legend
of a great dragon that attacks the sun, or the Egyptian story of a sow
that swallows the moon; and their cosmogonies can only be regarded as
poetical descriptions or survivals of early childlike notions of the
universe.

The Hindu world resting on the back of an elephant, and that on a
tortoise, is no doubt but an allegory. The Egyptians pictured the
earth as a great parallelogram, long from north to south but narrow
from east to west, like their own land, with the sky over it, upheld
by huge pillars or lofty mountains. The stars were set in this domed
lid of the world, but sun, moon, and planets were floating each in its
own boat on a great celestial river which ran just below the summits
of the mountains, and whose course was hidden towards the north. The
bark of the sun came nearer to Egypt in the summer, because at that
time the celestial river overflowed its usual bank, like the Nile. The
red _Doshiri_ was said to sail backwards, referring no doubt to the
retrograde movement of Mars.

In Eridu, one of the oldest cities of southern Babylonia, on the
Persian Gulf, the great abyss of the ocean was looked upon as the
origin of all things, and it was believed that it encircled the
earth like a great river. Later on, we find the world described as a
great mountain, resting on the watery deep, and under the mountain
is the abode of the dead. It is entered from the west, which surely
was suggested by the setting of the heavenly bodies in the west. The
vaulted sky above the earth has divisions: the rim of the lowest part
rests upon the supporting watery deep; above it are the upper waters
(the source of rain); and above this again is the dwelling-place of the
celestials. The sun issues forth each morning from a door in the upper
heaven, or from the mount of sunrise, and enters another heavenly door,
or the sunset mountain, at night.

The similarity to these Babylonian ideas of the Hebrew “firmament,”
the “waters above the firmament,” and the “of the great deep,” in the
book of Genesis,[23] and Ezekiel’s “Sheol” in “the nether parts of the
earth,”[24] has often been noted.

------------------------------------------------------------------------
[23] Gen. i. 6, 7; vii. 11.

[24] Ezek. xxxii. 18, 24.
------------------------------------------------------------------------

[Illustration: The Boat of the Sun travelling over the sky. [_To face
p. 46._

From an ancient Egyptian papyrus.

    The recumbent figure covered with leaves symbolizes
    the earth; the figure leaning over Earth, covered
    with stars, is the sky; the boat of the rising sun
    and of the setting sun floats over it. The central
    figure represents Maon, the Divine Intelligence
    which preserves the order of the universe.

(_Reproduced from Flammarion’s ‘Astronomical Myths,’ by permission of
Messrs. Macmillan & Co._)]

To sum up:—

If we include as astronomy any observation of the heavenly bodies which
leads to a recognition of order and periodicity in their movements
and a power of forecasting their positions, then every race and age
has had its astronomers, rough though their methods may be at first.
With growing civilization more refined methods are used; the gnomon is
invented for studying the movements of the sun; the changing positions
of moon and planets are noted by means of certain stars; finally, all
the visible stars are grouped into constellations, and it is recognized
that a great band of star-groups crosses the sky, which forms the
pathway alike of sun, moon, and planets; the length of the month and of
the year are determined more or less accurately, and when an unvarying
calendar has been formed, the celestial cycles can be better recorded
and studied. But in all this there is as yet no scientific motive
properly so called, no curiosity regarding the phenomena for the simple
pleasure of knowing and understanding them, no attempt to group them
into a system or to explain their underlying causes. The primitive idea
that the heavenly bodies exist for the convenience of earth-dwellers
is illustrated by the Egyptian hieroglyph for night, [glyph] which
consists of the sign for sky [glyph] combined with a star suspended
like a lamp; the other idea that they are mysterious divinities is
shown by the Babylonian star-sign for a god or king, [glyph]. The
ancients found that the stars were of great use, especially for
measuring periods of time; they recognised also in them a marvellous
order and regularity, of which they dreamed that they found an echo on
earth, and endeavoured to divine the future by watching the skies. Can
we doubt that they were also attracted by the beauty that calls all men
through all ages to lift their eyes and look upward?


           HYMN TO THE SETTING SUN.

       _Sung by the Priests of Babylon._

    Sun-god, in the midst of heaven,
        At thy setting
    May the latch of the glorious heavens
        Speak thee peace.
    May heaven’s door to thee be gracious,
    May the Director, thy beloved messenger, direct thee.

    Lord of E-bara, may the road of thy path be prosperous,
    Sun-god, cause thy highway to prosper,
        Going the everlasting road to thy rest.
    Sun-god, thou art he who is judge of the land,
        Causing her decisions to be prosperous.

                          From a lecture by T. G. PINCHES.
                             (_Nature_, Dec. 31, 1891).




_III. GREEK ASTRONOMY._

FIRST PERIOD. B.C. 900 TO B.C. 350.


    “Great men! elevated above the common standard
    of human nature by discovering the laws which
    celestial occurrences obey, and by freeing
    the wretched mind of man from the fears which
    eclipses inspired! Hail to you and to your genius,
    interpreters of heaven, worthy recipients of the
    laws of the universe, authors of the principles
    which connect gods and men!”

                                            PLINY
             (_Apostrophe to Thales and Hipparchus._)


1. HOMERIC GREECE.

To turn from the astronomy of Egypt and Assyria to the astronomy of
the Greeks is like coming to a sudden bend in a river which has flowed
through level country for many miles in a slow majestic course, and
finding beyond the bend a series of rapids and waterfalls. Instead of
patient age-long accumulation of observations, instead of a mystical
adoration of stars, supposed to be beyond man’s power to understand,
we find that the Greek’s first instinct is to inquire into the meaning
and the origin of what he saw, even before he had taken time to
investigate. Behind the varied splendours of earth and skies which
fascinated his bodily eyes, his intellect divined laws and forces which
held the whole together in a wonderful harmony. Then, as fresh facts,
or a fresh point of view, thrust itself upon him, a new explanation
must be attempted, and thus many complete systems of the universe were
evolved. Not the name only, the idea of Cosmos was Greek.

[Sidenote: Homer _c._ 900 B.C.]

[Sidenote: Hesiod _c._ 800 B.C.]

The first ideas of astronomy among the Greeks were as primitive as
those of any other race in its early stages. They evidently had no
conception of the sky as a sphere, or of the revolution of the stars
as a whole, round fixed poles, though they watched the motions of
certain bright star-groups, and called them by the names that we use
now (however these names may have reached them), as we see in Homer
and Hesiod. Ulysses, guiding his raft cunningly by night, keeps on his
left the Bear, also called the Wain, which turns round in her place and
keeps watch on Orion, and never bathes in ocean; he watches also the
Pleiades and the “slow-setting Ploughman” (Boötes)—an apt description,
as anyone may see who watches Arcturus, the brightest star of Boötes,
when low on the western horizon. Being a northern star, its motion
seems very slow, and makes so small an angle with the horizon that for
a long time Arcturus glides above it before finally dropping below;
whereas the Pleiades, or any other stars near the equator, move very
quickly and almost at right angles to the horizon, and so drop below it
quite suddenly. It is Ulysses also who warns his companion, when they
are setting out to spy upon the Trojan camp, that two watches of the
night are already past, “for the stars have gone forward.” The stars
also announced the seasons, for Hesiod says that the time of harvest is
indicated by the heliacal rising of the Pleiades, and when Orion with
Sirius stands in mid-heaven, and Arcturus rises in morning twilight, it
is time for the vintage.

Homer and Hesiod both mention Venus, as a morning star “the brightest
of all the stars, which comes to herald the light of dawn,” and also as
an evening star, apparently without recognizing that it was the same
star; as they do not mention any other planet we do not know if the
others were known to the ancient Greeks.

The first appearance of the new moon’s slender crescent was watched for
from hill-tops, and celebrated by sacrifices, and this—as with other
ancient nations—fixed the first day of their month.

[Sidenote: Mimnermus _c._ 580 B.C.]

Day seems to have been divided into three parts, morning, midday, and
evening, according as the sun was rising, or nearly stationary, or
sinking. The sun was thought to rest upon and slide over the solid dome
of the sky, otherwise perhaps it would have fallen to the ground; and
at night it was supposed to go behind Mount Atlas, and then to travel
behind high northern mountains to its rising place in the east. This
primitive explanation of its movements is so poetically described by
an early poet, Mimnermus, that I cannot resist a quotation, though the
lines can hardly be regarded as an astronomical fragment. They may be
freely rendered thus:—

    Endlessly toiling Helios speeds.
    No rest for him or for his steeds
      When Dawn has climbed the height.
    Soon as he lays his weary head
    Upon the golden wingèd bed
      Made by Hephaestos’ might,
    It bears him sleeping o’er the seas,
    Far from the fair Hesperides,
      Through realms of darkest night;
    Till in the Ethiopian land
    He sees his horses ready stand;
      And when the child of light,
    The rosy-fingered, early-born,
    Has ushered in another morn,
      He mounts his chariot bright.

The earth, as pictured on the shield of Achilles, was flat and round,
just as it appears from a height, and of course Greece was the centre,
just as Egypt was the centre of the Egyptian, and Babylon the centre
of the Babylonian cosmogonies. It was a small earth: a few countries
lay round the Middle Sea, and further to the south was the land of the
Ethiopians where the Sun passes overhead and burns the inhabitants
black; there was another sea to the north, over which the Argonauts
sailed, and in the extreme east was the Lake of the Sun, out of which
he rose every morning. This was a great gulf of the River Oceanus which
encircled the whole earth. Its sources were in the furthest west, just
beyond the Pillars of Hercules, and thence it flowed north, east, and
south, finally returning into itself. A branch from near the source,
called the Styx, flowed down into the underground world of Hades, the
abode of the dead, and beneath this again was Tartarus, where were
imprisoned the Titans who had fought against Jove.

Above the flat earth the blue dome of heaven was spread like a tent,
and across it travelled

    “The never-wearied Sun, the Moon exactly round,
    And all those stars with which the ample brows of
          heaven are crowned.”

What a compact little universe, and how important a part of it was man!
But as thought developed, the universe expanded.


2. THALES AND ANAXIMANDER.

[Sidenote: B.C. 585.]

[Sidenote: Thales _c._ 600 B.C.]

In the sixth year of the war of the Lydians against Cyaxares, king of
the Medes, just when a battle was about to begin, day was suddenly
changed into night by an eclipse of the sun, and Herodotus adds: Thales
had told the Ionians of this before, and in what year it would happen.
This does not necessarily imply any accurate understanding of eclipses
on the part of the Ionian philosopher. He had visited Egypt, and may
have learned from the priest-astronomers there that eclipses recur in
cycles and so can be predicted. But Thales was not content with cycles.
He wanted to know, not only that eclipses would happen at such and such
times, but _how_ they happened. Perhaps from reports of Babylonian
observations, perhaps from questions put to Egyptian astronomers, he
learned that solar eclipses only happen when the moon is new and in
the ecliptic, that is, in the same part of the sky as the sun, and
that the black body then seen on the sun has always a rounded edge.
These no doubt were the arguments on which he founded his assertion
that solar eclipses are caused by the moon passing in front of the sun;
and he further added that this shows the moon to be of an “earthy”
nature, that is, not made of fire or any substance either luminous
or transparent, but of opaque matter, probably having weight and
substance, and not altogether unlike what we know on earth. He is said
to have stated also that the moon receives her light from the sun,
a conclusion which would follow from a little attention and thought
bestowed on her phases.

Besides his speculations regarding the moon, Thales took pains to note
the sun’s movements as accurately as possible, by means of gnomons,
with a view to discover the exact length of the solar year, and it was
he who advised the Greeks to adopt the Phoenician method of directing
their course at sea by the Little Bear instead of the Great Bear, which
appears to have been the constellation used in Homeric times.

Thales imagined that Ocean did not merely encircle Earth, but that the
whole Earth, which was a thin flat disc, floated upon the Ocean.

This zealous observer must have had something of the absent-mindedness
of his great successor, Newton; for it is told of him that while
star-gazing he fell into a well!

[Sidenote: B.C. 611-545. Anaximander]

It is evident that the moon’s passing in front of the sun implies a
lesser distance from us, and it must have been this which suggested her
place in the scheme of Anaximander. This scheme is rather difficult to
understand, from the allusions and quotations of later writers, for
we have no original writing by Anaximander; but we can gather enough
to show that already in the sixth century B.C. the Greek philosophers
were asking themselves what was the explanation of the movements and
appearances of the heavenly bodies, how they were supported in the
sky, what force moved them, how large and how distant they were, and
what they were made of. Anaximander asserted boldly that sun and moon
were larger than the whole earth: he thought the sun might be 27 and
the moon 19 times as large. How he reached this conclusion it is
impossible to say. The Egyptians had already tried to measure the
apparent size of the sun as compared with the circumference of the sky,
by noting how long it took to set from the moment the lower rim touched
the horizon to the moment when the whole disc disappeared: this,
divided by the 24 hours taken by the sun to traverse the 360 degrees of
the sky, gave the sun’s size in degrees (it is about half a degree),
and had they been able to find the actual distance of the sun from the
earth, they could have deduced its actual size, but this they had no
means of determining.

There are two possible ways of seeing that the moon is smaller than
the sun, although they usually appear to us the same size. Anaximander
may have seen or heard of an “annular” eclipse, in which the moon is
rather more distant from us than at a total eclipse, and therefore
her dark body just fails to cover the whole sun, and a bright ring of
light surrounds her. More probably he realized what was implied in
Thales’ explanation of solar eclipses, and concluded that the moon must
be smaller than the sun, because she looks no larger although she is
nearer to us.

His scheme is the first of which we have any knowledge in which the
movements of the heavenly bodies are explained by supposing them not
all in one sky together, but placed in a series of heavens, one above
the other: hence it is of peculiar interest to the Dante student, for
in it we trace the first attempt towards the theory of the Revolving
Spheres. It is true that the Babylonians and Hebrews divided their
heaven into three parts, one above the other, but this was only to
divide the place of atmospheric phenomena from the dwelling-place of
the gods, and sun, moon, planets and stars all moved in the same
heaven. Here, in the universe of Anaximander, we find one heaven, the
lowest, for air, rain, etc., another for all the stars, a higher heaven
for the moon, a yet higher for the sun, and above all the region of
fire, the brightest, lightest element, whose nature it was to ascend
and which therefore is outside all, as it was the nature of earth
to descend and therefore to be at the bottom. Probably either in or
above the heaven of celestial fire was the heaven of the gods, for, as
Aristotle remarks, all our ancestors, indeed all who believe in gods at
all, whether Greek or of any other race, place the dwelling-place of
the gods above in high heaven, as the unchanging, unmoving region of
eternity.[25]

------------------------------------------------------------------------
[25] _De Cœlo_ I. 3, and II. 1.
------------------------------------------------------------------------

Unfortunately we do not know what would be of great interest, whether
Anaximander also provided separate heavens for the planets, or found
a home for them in the heaven of the stars. Perhaps he hardly knew of
their existence, or said with Aratus who wrote nearly 800 years later:—

    “Of these I dare not speak with certainty,
    As of the fixed stars’ orbits.”

The successive heavens were in layers, as it were, one above the
other, “like the bark enclosing a tree,” but they were transparent and
invisible. The heavens themselves were not in motion, carrying the
stars, sun, and moon; Anaximander had an ingenious mechanical scheme
of wheels or rings to carry them inside their respective heavens,
which doubtless was clear to himself, though unfortunately it is not
at all clear to us. Some writers have maintained that these heavens
were spheres, but for several reasons it is difficult to believe this,
and probably the sky was still to Anaximander, as to the Homeric
Greeks, a slightly flattened hemisphere,[26] only divided into these
layers, and instead of ending at the horizon it continued a little
below, to allow of the passage of the heavenly bodies between setting
and rising. Perhaps it was for this reason that he gave the earth a
greater thickness than the disc of Thales, comparing it to a short
thick pillar, three times as broad as high, the top of which only was
inhabited. His Cosmos, then, would be something like the diagram, with
regard to the disposition (though not the relative sizes) of Earth and
the heavenly bodies.

------------------------------------------------------------------------
[26] But see note, pp. 75, 76.
------------------------------------------------------------------------

[Illustration: Fig. 12. The Universe according to Anaximander.]

Somewhat timidly the barriers have been thrust back. The earth goes a
little deeper into the dark unknown, the sky is wider and higher, the
heavenly bodies are much larger and more distant and go under Earth’s
surface; but they are cautiously upheld by solid domes, and worked by
wheels. Earth is still the floor of the World, and Heaven—now a series
of heavens—the vaulted roof above.


3. LATER FLAT EARTH SYSTEMS.

It is interesting to see how long this timidity persisted among the
Greek philosophers, especially of the Ionian school, in spite of the
fact that other schools had advanced much bolder ideas, as we shall
presently see. Quite a number of universes were constructed somewhat
after the pattern of Anaximander’s, with Earth as floor of the world;
but some placed the stars beyond moon and sun, some definitely included
the planets, though they do not seem to have explained their motions;
and there were various ways of supporting the flat earth, and of
supporting and moving the heavenly bodies.

[Sidenote: Anaximenes _c._ 550 B.C.]

[Sidenote: Empedocles _c._ 450 B.C.]

[Sidenote: Anaxagoras died 428 B.C.]

Anaximenes, a follower of Anaximander, having doubtless pondered
the fact that very heavy bodies can float in water if only they are
the right shape, and that Earth itself was supposed by Thales to be
floating on the Ocean, suggested that the moon is so broad a disc that
she floats in the ether, “like a leaf,” and of course the same would
apply to the sun. Two later philosophers, Empedocles and Anaxagoras,
held that a great whirlwind swept continually round the Earth, which
both kept the heavenly bodies from falling down upon it and drove them
across the sky.

Equally diverse were the opinions as to the nature and composition of
the heavenly bodies. Most philosophers of this age believed that they
were of pure fire, or else that they were vessels containing fire,
which was extinguished, or in one way or another became invisible to
us, during eclipses and when they set. Others held, as we have seen
with Thales, that they were of an earthy nature; and Anaxagoras, seeing
a meteorite which had fallen from the sky during the daytime, thought
he actually held a piece of the sun in his hands, and concluded that
the sun was an enormous mass of iron, “much greater than Peloponnesus,”
and shone because it was red-hot. But the popular idea still was that
the sun was a god, or the chariot driven by a god across the sky, and
Anaxagoras was banished from Athens for his impious words.[27] The
markings on the face of the moon were thought to prove that she was of
mixed composition: she was made of air mingled with only a little fire,
or earth mingled with fire; but according to Democritus the markings
were shadows of mountains on her surface, and Anaxagoras is reported to
have said that the moon was inhabited, and the markings were “plains
and valleys.”

------------------------------------------------------------------------
[27] His life was saved by his illustrious pupil, Pericles, of whom
the story is told that on one occasion, just as his army was embarking
for an expedition, the sun was eclipsed, and his pilot was terrified.
Pericles snatched off his cloak, and held it so as to hide himself from
the man’s eyes. “Is that terrible? is that an evil omen?” he cried.
“Then do not fear the disappearance of the sun, for it is just the
same, only the thing that hides it is larger than my cloak.”
------------------------------------------------------------------------

Anaxagoras suggested that the stars were fragments torn off the
circumference of the earth by the encircling whirlwind, and that they
glowed with the heat caused by friction, though they were too distant
for us to feel this heat, being far beyond the sun. The Milky Way was
a source of speculation: some said it was the former path of the sun,
and still burning from his heat, but Democritus explained it as caused
by the shining of innumerable stars, too faint and close together to be
distinguished separately.

The doctrines of the different philosophers as to origin and first
stages of the universe do not concern us here, but we must mention that
of Empedocles, as his views are directly referred to by Dante.

This philosopher was the first to assert that everything consists of
the four elements, earth, air, water, and fire, pure or in combination;
and the combinations he supposed to be brought about by two forces, one
attractive, the other repulsive, which he named Love and Discord. Of
these, one alternately predominates at different ages of the world, and
thus its history is divided into periods of different character.

A great step forward was taken when it was realized that the sky is not
a hemisphere, ending at the horizon, or even extending a little way
below, but that it surrounds Earth in every direction, like a sphere.
This idea probably originated with the Pythagoreans, or it may have
occurred independently to several thinkers, when the diurnal motion of
the heavens was better observed, and geometrical conceptions understood
and applied. Now it became no longer necessary to extinguish and
rekindle the stars, nor to send the sun round swimming on River Ocean
behind northern mountains, or creeping through strange underground
regions, through the night. It was clearly recognized that the visible
course of each heavenly body was part of a circle, the whole of
which we could see if we could only travel fast enough and go to the
underside of the earth.

[Illustration: Fig. 13. The Universe of Leucippus.]

[Sidenote: Leucippus _c._ 450 B.C.]

[Sidenote: Democritus _c._ 430 B.C.]

But this was just what never could be done, for outside the schools
of the Greeks in Italy (Pythagorean and Eleatic), Earth still had
an uninhabitable underside. Distinguished men like Leucippus and
Democritus sought to combine the belief in an all-surrounding spherical
heaven with a flat supported earth which might still give them a solid
floor beneath their feet. Leucippus made the earth a hemisphere, with a
hemisphere of air above, the whole surrounded by the supporting crystal
sphere which held the moon. Above this came the planets, then the sun,
and probably the stars were outside this. His disciple, Democritus, on
the other hand, retained the disc-like earth, raised a little at the
rim, to secure its contents, and made it divide the sphere of air into
two parts, so that it rested upon air, and air was also in the sky
above. The underside of the disc was not inhabited, no doubt because
no one could stand upside down. His order of the successive heavens is
not quite the same as that of Leucippus, as he puts the moon and the
Morning Star together, and the rest of the planets beyond the sun.

[Illustration: Fig. 14. The Universe of Democritus.]

This scheme gave the universe a beautifully symmetrical form, which
must have pleased the Greeks, but now they were puzzled to know why
the heavenly bodies did not circle symmetrically with regard to the
central earth. Why was not the pole in their zenith and the equator on
the horizon? They could only guess that it must have been so at first,
and that the disc had slipped out of position, either through some
irregularity in its weight, or in the density of the underlying air.
Compare Milton’s—

    “Some say He bid His angels turn askance
    The poles of Earth twice ten degrees and more,
    From the Sun’s axle; they with labour pushed
    Oblique the centric globe.”
                          _Paradise Lost_, Bk. X., 563-566.

All these theories and guesses may seem to us very crude and fanciful,
and we may compare them to the eager questionings of intelligent
children, too impatient to consider whether the answers given are
satisfactory explanations or no. But we must remember that all we know
of the early cosmogonies is from allusions and descriptions by later
writers, who often—like Aristotle, for instance—only quote to condemn.
“If each could defend his own opinion, may be we should see that there
is truth in all.” (Conv. IV. xxi. 25-7).

At least we find a keen and disinterested desire to penetrate the
causes of things, and a fertile imagination, without which science
can make no advance: moreover there was a progress in true knowledge.
It was discovered that the (apparent) diurnal paths of sun, moon, and
every star were circles, although only a part of the paths could be
seen; and that, although all were seen projected on a sphere, their
actual distances from earth were very varied.

It is disappointing to find no record of observations of the planets,
and from the almost random way in which they were placed in the heavens
it seems that but little attention had been paid to them as yet. In
fact, Seneca tells us that Democritus knew neither their number nor
their names. They were often classed with comets, and thought to be
entirely erratic, and the Greek mind was more attracted towards those
phenomena which were seen to be orderly.


4. PYTHAGORAS AND HIS FOLLOWERS.

    _Socrates._ As the eyes are appointed to look up
    at the stars, so are the ears to hear harmonious
    motions, and these are sister sciences. That is
    what the Pythagoreans say, and we, Glaucon, assent
    to them?

    Yes, he replied.

[Sidenote: Pythagoras _c._ 540 B.C.]

About the same time that Anaximander was inventing solid hemispheres
and rings to hold and move the heavenly bodies round about a flat
earth, Pythagoras was founding a school in southern Italy which gave
to the world a very different scheme. One of the characteristics of
his school was secrecy, its methods were oral, and his later followers
were fond of attributing to their master everything which had gradually
grown out of his teaching: it is difficult therefore to say with
certainty what he himself taught. It has often been stated by modern
writers that he anticipated Copernicus, and discovered that the earth
revolves round the sun. Though this is a mistake, we may venture to
believe that Pythagoras taught that the earth is a sphere, hanging
freely in space.

We are so familiar with this idea from childhood, that it is difficult
to imagine what a tremendous innovation it was. Pythagorean noviciates,
doubtless after solemn initiation and preparation, were told: This
earth, which seems to you the floor of the world, with heaven stretched
over it like a tent, is a round globe, with men like you living on
the other side of it, and yet they do not fall, and earth does not
fall, for it is poised in the centre of the world, and has no tendency
to fall in one direction rather than in another. Earth, itself a
perfect sphere, is in the centre of an infinitely greater sphere, the
star-set heaven; and within this seven heavenly bodies move in perfect
circles, each at its proper distance and pace, all needing no support
and no force to drive them, for harmony is the motive power of the
Cosmos. Their distances are proportional to the intervals between
musical notes, and as they circle they make heavenly music, which we
should hear did we not always hear it, like one who lives beside a
waterfall[28]. There is no below, and no above, for above is below and
below above to our antipodes: there is but the centre, where we live,
and Heaven is all around.

------------------------------------------------------------------------
[28] Some late followers said that Pythagoras, alone amongst men, could
hear the music of the spheres.
------------------------------------------------------------------------

How did Pythagoras reach this great and startling truth of the round
unsupported earth?

His school relied more on experiment and observation than the Ionian,
and the colonizing Greeks of Italy had travelled. They might have
noticed the curvature of the sea, and the varying height of the Pole
Star according to latitude. We know that in early days the Greeks were
struck by the remarkable fact that the brilliant star Canopus (second
only to Sirius in brightness), which was invisible in Greece, could
just be seen close to the southern horizon in Rhodes, and was well
seen in Egypt. Then the moon may have helped once more. When it was
understood that lunar eclipses only happen at full moon, when we are
between her and the sun, and that they may therefore be explained by
the earth’s shadow falling on the moon, then, since the edge of that
shadow is always a circle, it is demonstrable that the body throwing
that shadow can have no form but that of a ball.

Sun and moon are obviously round: it was guessed that they also are
globes rather than discs, and the spherical shape of all heavenly
bodies was a doctrine of the later if not the earliest Pythagoreans.

Whatever may have been the steps which led to these two great
discoveries that Earth is a sphere, and that the apparent path of
every celestial body is a circle, the sphere and the circle were soon
accepted as the only forms suitable for celestial bodies and their
orbits. The founder of the school was a great mathematician, and it
is not strange that these forms should have commended themselves to
his disciples. The sphere, which has its surface everywhere similar,
and its contents greater than those of any other figure with equal
surface, was the “most perfect” of solids; and the circle, which has
no beginning and no end, is alike in every part, and presents ideas
of haunting suggestiveness to the geometer, was the “most perfect” of
lines.

In the system of Pythagoras we first find the five planets distinctly
enumerated, and playing as important parts as sun and moon. Number was
the principle of this universe, and the planets with sun and moon made
the sacred number of seven. Among the Greeks, and through the middle
ages, all these bodies are spoken of as planets or “wanderers,” in
distinction from the “fixed” stars which do not appear to move amongst
themselves. These seven “planets” represented the seven notes of a
musical scale, and the star sphere made up the octave. Pythagoras is
said to have been the first to teach that Phosphor and Hesperus, the
morning and the evening star, were the same. When, however, we ask
what was the order of the planets in his scheme, we meet with many
conflicting reports, and a serious difficulty suggests itself. If
the planets had really been observed with care, it must have been
seen that their motions could not be accounted for by simple circular
movement. The large oscillations of Mercury and Venus on either side
of the sun would strike an observer before he thought of tracing their
movements among the stars, and noting that they made a circuit of the
zodiac. Similarly, the other planets are most conspicuous, rising after
sunset and remaining long visible through the night, at the very time
of their retrograde movements, so these must have been noticed if a
long enough series of observations had been made to distinguish them
from one another. The only solution of the difficulty seems to be that
Pythagoras, on the journeys into Egypt and Babylon which he is said
to have made, learned that there exist planets to the number of five,
which move in regular periods, and he may also have learned the length
of their zodiacal periods at the same time, or perhaps these were only
known to his school much later. If the order assigned to them was that
which was finally and generally accepted by the ancient world, the
periods must have been known, for this is the only possible clue to the
order Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn. The planet with
shortest period (the moon, with a month) was naturally placed by the
Greeks nearest to earth, with the smallest circle to traverse, and so
on outwards.

It is very possible, however, that the early Pythagoreans, at least,
did not venture to assert more than that there were five planets,
without assigning to them any order, for Aristotle tells us that their
universe was divided thus:—

From Earth to Moon was the Ouranos, or sky, within which exists all
that is changing and corruptible.

Cosmos, the place of ordered movement, was the region of Sun, Moon, and
Planets.

Olympos, the place of pure elements, held the stars; the region of
Celestial Fire came beyond this, and the Apeiron, the Infinite Space,
or Infinite Air, from which the world draws its breath, was outside all.

[Sidenote: Philolaus towards end of 5th century B.C.]

The diagram shows, then, the earliest form of the Pythagorean universe.
But they did not remain content with this. Out of it grew a most
interesting scheme (referred to by Dante), which is usually attributed
to one Philolaus, of whom hardly anything is known, not even his date.

It seems to have struck Philolaus as a difficulty that the seven
planets, which were circling round Earth in the same direction but
at very different distances and speeds, and also the immense sphere
of stars beyond, were all sweeping together at the same time in an
opposite direction, and at the almost incredible pace of one revolution
in a day. The brilliant idea occurred to him: Leave the stars at rest,
let the seven planets revolve in their seven orbits, the nearer to the
centre the faster, and let earth herself revolve fastest of all, viz.
in twenty-four hours, in the same direction. If she keeps one face
always turned towards the centre, like the moon, this will account
quite as well for the apparent diurnal revolution of all the heavenly
bodies, and the change of day and night on the earth.

Philolaus did not make Earth remain stationary and simply turn on her
axis, which would have had just the same effect on the apparent motions
of the heavens; for it seemed more natural that she should revolve as
did the rest. The five naked eye planets are all mentioned by name in
his scheme.

[Illustration: Fig. 15. The Universe of Pythagoras.]

Was the centre, deprived of Earth, to be left empty? No, the centre
was the Watch Tower of Zeus, the Hearth of the Universe, and here they
placed the purest element, fire. It was invisible to us, because we
live on the side of the earth-sphere turned away from the centre; and
also invisible to us was another planet, Antichthon, or Counter-Earth,
for this revolved within our orbit, and also in twenty-four hours. It
was added to the system, because the addition of Earth as a heavenly
body spoiled the sacred number of seven, but by adding Antichthon, and
counting the star sphere as another, the total was brought up to ten,
another sacred number.

The objection was made that, if Earth is moving in space, this must
bring about a change in the apparent sizes of sun and moon, as Earth is
nearer or farther from them, but the Pythagoreans were quite ready to
believe that all the heavenly bodies are so distant that this journey
of Earth makes no difference to their apparent size or brightness. The
planets were thought to be worlds like ours, and inhabited; and it was
even guessed that plants and animals on the moon must be fifteen times
as strong as ours, apparently because there the average day consists of
nearly fifteen of our days (of twenty-four hours), and the nights are
equally long.

It was the braver of the Pythagoreans to shake the steady earth from
her centre, and set her whirling in the depths of space, that they
realized, as no one had done before, how large she must be; for Greece
and the surrounding lands, the Middle and the other seas, instead of
making the whole of the earth, were now understood to be only a portion
of a great globe.

[Illustration: Fig. 16. The System of Philolaus: night on earth.

Only the side turned away from the centre is inhabited: consequently
the Central Fire and Antichthon are invisible.]

[Illustration: Fig. 17. Twelve hours later: day on earth.

Earth has made half a revolution and her outer side is now lighted by
the sun, which has only moved about half a degree forward in its yearly
orbit. Antichthon has also made half a revolution, therefore remains
invisible.]

Here, then, is a conception of the Universe widely different from
Homer’s. The little flat disc has become a great round ball, a planet
among planets, swiftly moving through space; the crystal dome that
tenderly covered it like a bell-glass over some fragile flower, has
lifted, and the vast sphere is seen, infinitely distant, and studded
with enormous stars. Man himself is now a tiny creature on a great
earth, and his world but one among many, but if he is humiliated by his
insignificance, is he not elevated by the vastness of his outlook?

[Illustration: Fig. 18. Earth and sun according to Heracleides.

In the upper figure it is day, in the lower, night, on the inhabited
side of Earth. The sun is on the equator, as at the time of equinox.]

[Sidenote: Heracleides _c._ 370 B.C.]

But not even here did the Greeks stop. It was taking a less startling
step than they had already taken, to reach the truth that Earth was
merely rotating on her axis once in a day, and so causing the apparent
diurnal revolution of the heavens. This step was taken (it is said)
by a Pythagorean called Hicetas of Syracuse, who is quoted as saying
that the earth, “while it turns and twists itself with the greatest
velocity round its axis, produces all the same phenomena as if the
heavens were moved and the earth were standing still.” We are told also
that “Heracleides of Pontus and Ecphantus the Pythagorean let the earth
move, not progressively, but in a turning manner like a wheel fitted
with an axis, from west to east round its own centre.”

A brilliant guess,[29] which seems fully justified by facts, has
recently explained the personalities of these two mysterious
Pythagoreans of unknown date, Hicetas and Ecphantus, whose names have
been coupled for centuries with that of Heracleides, as teaching the
rotation of Earth on her axis. It seems that they resemble the Shadow
in Hans Andersen’s tale, which became a man and lived apart from the
man to whom it originally owed its existence, for it is now thought
that they were speakers introduced by Heracleides into one of his
dramatic dialogues to discuss astronomy.

------------------------------------------------------------------------
[29] See Heath’s _Aristarchus of Samos_, pp. 187-189 and 251, 252.
I very much regret that as Mr. Heath’s book was only published this
year, I have been unable to make use of it while writing of early Greek
astronomy. I can now only advise any readers who may be interested in
my brief sketch of this period to read Mr. Heath’s history, where they
will find the opinions of modern writers summarized and discussed,
and also the full text (in English) of the most ancient and reliable
sources of information. It is a great encouragement to find that my
statements are in agreement with his in nearly all essential points,
but readers will mark the following important differences:—

1. Anaximander’s heavens are said to have been spherical, not
hemispherical, and this seems to be clearly proved by the evidence
quoted from ancient writers.

2. Anaxagoras, not Thales, is said to have been the first to explain
correctly the cause of solar eclipses and of the moon’s phases, viz.
that the moon is an opaque body, shining only by reflected sunlight,
and periodically hiding the sun from us when she passes in front of
it. Mr. Heath regards the authorship of Anaxagoras as conclusively
proved: readers will be able to judge of this from his quotations.
Personally they seem to me to prove no more than that Anaxagoras agreed
with others on this point, and was the first to express it clearly in
writing. It is difficult to see why Mr. Heath denies that Parmenides
held the same views before Anaxagoras: Parmenides’ own words seem to
prove it, and his theory that the moon was composed of air and fire
mingled is rather in favour of it than otherwise. He surely meant that
the moon was not wholly bright, like the sun; yet that she had some
light of her own must have seemed evident from the faint illumination
we see during total lunar eclipses and on the part of her surface not
lighted by the sun. (See Dante’s views, p. 402 of this book.)

The connection between her phases and her distance from the sun in the
sky is so extremely obvious that I can hardly think the Greeks drew no
inference from it until the fifth century B.C., and I cannot see why
we should refuse to credit Thales with the discovery attributed to him
that her light came in some way from the sun. Gruppe acutely observes
that the reason why Thales’ pupil Anaximander did not accept the true
explanation of lunar phases and solar eclipses may have been because
he felt it necessary to have a theory which would apply equally well
to eclipses of the moon; and as he believed in a flat earth he could
not advocate the true explanation here. This was why he invented a new
theory (viz. that both sun and moon were fire shining through holes in
hollow rings, and that the occasional stopping up of these holes caused
both lunar and solar eclipses, and also the lunar phases).

But Parmenides had learned the Pythagorean doctrine of Earth’s
spherical form, hence he was able to accept the older theory that the
moon obtains her light from the sun, and sometimes eclipses the sun by
her opaque spherical body, for he could have added that the moon is
eclipsed in like manner by the opaque spherical body of the earth.

Heracleides, therefore, was the sole author of this remarkable
discovery.

In this way Earth was restored to her central position, but as a
rotating sphere, and the later Pythagoreans apparently tried to
reconcile their new scheme with the old by calling Antichthon the
uninhabited hemisphere of Earth, and placing the central fire within
the earth.
------------------------------------------------------------------------




IV. GREEK ASTRONOMY.

SECOND PERIOD. B.C. 400 TO A.D. 150.

    “Chiamavi il cielo, e intorno vi si gira,
    Mostrandovi le sue bellezze eterne.”


1. PLATO.

The Ionian school of philosophy died about the middle of the fifth
century B.C., and the Pythagorean towards the end of the fourth. But
meanwhile a new school of astronomers was growing up. The philosophers
still laid down general principles, founded on abstract reasoning,
which they believed must regulate the nature and movements of the
heavenly bodies, but astronomy began to be regarded as a branch of
mathematics, not of philosophy, and the mathematicians, leaving
problems of ultimate causes to the philosophers, devoted themselves
to observation and calculation. They carefully studied the peculiar
motions of each planet, and their chief aim was to represent these
geometrically by some scheme which should include them all, and make it
possible to predict the places of the heavenly bodies in the sky for
any given date.

One cause of this great progress in methods was no doubt the natural
intellectual growth of the Greek race, as they discovered that their
eager curiosity concerning nature could only be satisfied by patient
investigation. The value of observation was taught, in the latter half
of the fourth century, by the philosophy of Aristotle, and a great
impetus must have been given by the campaigns of Alexander, in which
the Greeks saw distant countries, new climates, strange peoples and
customs.

[Sidenote: Callisthenes _c._ 330 B.C.]

But a potent cause of the advance in astronomy seems to have been the
closer connection between Greek astronomers and those of Egypt and
Babylon. The astronomer Callisthenes went with Alexander to the East,
and received a letter from Aristotle praying him to send to Athens the
Babylonian eclipse records which were centuries old; and Aristotle
mentions, when speaking of the motions of the planets, that the
Babylonians and Egyptians had furnished trustworthy information about
each one of them. Even before this, we find that the Greek descriptive
names of the planets were changed for names of Greek deities which
are believed to correspond with the Babylonian gods and goddesses
who presided over the planets. Thus Plato speaks of “the star sacred
to Hermes” as well as Stilbon the Glitterer, and he is the last to
use commonly the name of Phosphor for the planet which henceforth
was known as Aphrodite among the Greeks, and Venus among the Romans,
corresponding with the Babylonian Ishtar; and so on with the rest.
Instead of vague records of journeys in Egypt or Babylonia, we have a
definite statement that Eudoxus, who was the founder of the new school,
went to Egypt about 378 B.C., with letters from the king of Sparta
to the king of Egypt, and we are told that he studied the planetary
motions under a priest of Heliopolis. It seems highly probable, to say
the least, that Eudoxus was the first Greek to appreciate the value
of those methods of observation and continuous recording of phenomena
which he found among the Egyptians, and to understand the wonderful
regularity which was hidden behind the seeming irregularities of the
“wandering stars.” He was also, apparently, the first Greek to write a
detailed description of the forty-eight ancient constellations.

But if Egypt and Babylonia gave to Greece records of celestial
phenomena, and set the example of accurate and long-continued
observations, Greece made the new knowledge her own, and transformed
it. The legend that Eudoxus applied his mathematical skill to the
ancient monuments of the Egyptians, and showed them how to calculate
the height of the Great Pyramid by measurements of its shadow, is
typical of the history of Greek treatment of Oriental astronomy.
One geometrical theory after another was invented to represent
the planetary motions, was compared with the skies, and rejected
or improved, and meanwhile observation became much more close and
accurate; new instruments were introduced, new methods of calculation
invented, new motions discovered which had to be accounted for;
finally, five hundred years after Eudoxus’ visit to Egypt, the result
of all this labour was summarized in a truly epoch-making work,
which remained the standard treatise on astronomy until the time of
Copernicus.

[Sidenote: Plato _c._ 427-347 B.C.]

Eudoxus was born at Cnidos, in Asia Minor, but at the age of
twenty-three he went to Athens, and studied under Plato. It is said to
have been Plato who inspired the young man with the idea of devoting
his brilliant mathematical powers to solving the problem of celestial
motions, and with this view he went to Egypt. The story is easy
to believe when we recall the many passages in the _Dialogues_ in
which Plato uses the splendid imagery of the skies to illustrate his
philosophic doctrines, dwelling especially on the perfect though little
understood symmetry of the celestial motions, and it will be remembered
that astronomy was one of the subjects to be learned by the rulers of
his ideal state.

It is true that Glaucon is gently but decidedly snubbed by Socrates in
the _Republic_, for suggesting that the study of astronomy is valuable
because of its use in navigation, husbandry, and the arts of war. This
is “vulgar praise,” but has there ever been nobler praise of astronomy
than that which Socrates himself then proceeds to give? Although he
believes that true knowledge, knowledge of realities, is only to be
obtained by the exercise of pure reason without the aid of sense, he
considers that the study of celestial motions is one of the best means
of training the mind to reach those heights, and he does not hesitate
to say that sight was given to us in order that we might look at the
skies. For the embroidery of heaven, says Socrates, though wrought upon
a visible ground, is the fairest and most perfect of visible things;
and it is displayed to our mortal eyes as a pattern of the eternal
realities which are granted to the vision of the soul.

In the _Timaeus_ this idea is elaborately developed, and it undoubtedly
had an effect on Plato’s contemporaries, although his direct influence
on astronomy cannot be compared with that of Aristotle. The _Timaeus_
was widely read also in the Middle Ages, during the long period when
Plato’s other writings were unknown, and it is quoted by Dante.
We are often reminded of him when reading the astronomical and
quasi-astronomical parts.

Timaeus, who is introduced to Socrates by Critias as “the most of an
astronomer among us, and one who has made a special study of the nature
of the Universe,”[30] describes the Creation as he conceives it most
probable that it took place. He assumes a chaos to begin with, where
there is no order, and no matter which can be distinguished by name,
but all is confused and seething with random restless motions.

------------------------------------------------------------------------
[30] I follow the translation of Jowett.
------------------------------------------------------------------------

Of this, in order to produce something which should express his own
goodness,[31] the Creator formed the four elements,—earth, water,
air, and fire,—and of them he made a world, which became a fair and
intelligent being, animated by a living soul. He made it in the most
perfect form, that of a sphere, polished and smooth on the outside, “as
if from a lathe.” The soul was placed in the centre, and hence diffused
throughout the whole bodily frame. It is the cause of the harmonious
motions of the stars, and of these there are two kinds: the motion
of the Same (the diurnal revolution of the whole heavens) is in the
noblest direction, simple and uniform; the motion of the Diverse is in
the opposite direction and diagonal to the first, and it is divided
into seven parts (the seven orbits of the planets), which bear certain
definite ratios to one another.

------------------------------------------------------------------------
[31] Compare _Par._ vii. 64-66.
------------------------------------------------------------------------

Timaeus does not name the planets, but in the _Republic_ Socrates
names some, and indicates the rest by their colour or other
characteristic,[32] so we know that the order which he assigns to them,
counting outwards from the central earth, is: Moon, Sun, Mercury,
Venus, Mars, Jupiter, Saturn.

------------------------------------------------------------------------
[32] See his famous description of the eight spheres, on each of which
stands a siren, singing, while the whole system turns upon a diamond
spindle, the end of which rests upon the knees of Necessity. This book
was not known in the Middle Ages.
------------------------------------------------------------------------

It was in order to make the world like its eternal pattern that the
Creator made a “moving image of eternity,” which we call Time, in the
revolutions of the heavenly bodies; and to make it visible he “lighted
a fire which we now call the sun, in the second of these orbits, that
it might give light to the whole of heaven [note that the stars shine
by reflected sunlight, as well as moon and planets], and that the
animals who were by nature fitted might participate in number: this
was the lesson they were to learn from the revolutions of the Same
and the Like. Thus, then, and by these means, the night and the day
were created, being the period of the one most intelligent revolution.
And the month was created when the moon had completed her orbit and
overtaken the sun; and the year, when the sun had completed his own
orbit. The periods of the other stars [the planets] have not been
understood by men in general, but only by a few, and they have no name
for them, and do not estimate their comparative length by the aid of a
number, and hence they are hardly aware that their wanderings, which
are infinite in number and admirable for their variety, make up time.
And yet there is no difficulty in seeing that the perfect number of
time completes the perfect year when all the eight revolutions, having
their relative degrees of swiftness, are accomplished together, and
again meet at their original point of departure, measured by the circle
of the Same moving equally.”

The heavenly bodies, according to Timaeus, are all divine intelligent
beings. In form they are perfect spheres, like the world of which they
form part, and they are composed of fire. The stars have two motions,
for each rotates on its own axis while it is carried round the centre
on the rotating star sphere.

Earth is also a sphere, immoveable at the centre of the World. Of her
Timaeus says: “The earth, which is our nurse, encircling the pole
which is extended through the universe, he made to be the guardian and
artificer of night and day.”

This passage has given rise to the idea that Plato believed the
apparent diurnal revolution of the heavens to be caused by earth’s
rotation on her axis; but the word here translated “encircling”[33] may
mean—as that does—either motion or situation round about something,
and the whole context ascribes the diurnal movement so clearly and
emphatically to the heavens, that it seems evident Plato could only
have meant that earth was guardian and artificer of day and night by
virtue of her position. The only strong argument in favour of the
other meaning is that Aristotle, when speaking of Earth as supposed
by some to be central in the Universe but moving, quotes Plato and
the _Timaeus_. It might easily happen, however, that Aristotle knew
from other sources, perhaps from conversation with Plato, that at some
time the latter had inclined towards belief in Earth’s motion, and
remembering the ambiguous expression in the _Timaeus_ he quoted it from
memory as a statement of Plato’s belief.

------------------------------------------------------------------------
[33] ειλλομενη.
------------------------------------------------------------------------

There is some evidence that late in life Plato accepted the doctrine
of Philolaus that Earth was not only in motion, but in motion round a
Central Fire. There is a legend that he bought the books of Philolaus
at a great price, and Theophrastus, a disciple of Aristotle, is
reported by Plutarch to have said that “Plato when old assigned to
Earth another place, the central and nobler place being reserved for
something else more worthy of it.” However this may be, he does not
teach either theory in his writings. His views seem to be quite the
same as those of Pythagoreans of the old school, whom he sometimes
quotes.

After describing the creation of the Universe, Timaeus relates that
the Creator deputed the gods whom he had made (including the stars)
to create living beings on the earth, he himself creating directly
only their immortal part, which he made of the same essence as the
World-Soul, but diluted. Then follows the passage which came to the
mind of Dante when he met the first spirits of Paradise in the moon.

    “And when he had framed the Universe, he
    distributed souls in equal numbers to the stars,
    and assigned each soul to a star; and having placed
    them as in a chariot, he showed them the nature of
    the Universe, and the decrees of destiny appointed
    for them, and told them that no one should suffer
    at his hands, and that they must be sown in the
    vessels of the times severally adopted to them....
    He said that he who lived well during his appointed
    time [on earth] would return to the habitation of
    his star, and there have a blessed and suitable
    existence.” If he lived ill, he would be a woman
    at his second birth, if a bad woman, then a beast,
    and as long as he continued to do ill he would “not
    cease from his toils and transformations until he
    followed the original principle of sameness and
    likeness within him.... When he had given all these
    laws to his creatures ... he sowed some of them in
    the earth, and some in the moon, and some in the
    other stars which are the measures of Time.”

The creation of man’s body and all the remainder of the _Timaeus_ does
not concern us here, except that when speaking of the highest use of
man’s faculty of sight, we realize how near Dante and Plato are in
their feeling for the revolving heavens:

“God invented and gave us sight to this end, that we might behold the
courses of intelligence in the heaven, and apply them to the courses
of our own intelligence which are akin to them, the unperturbed to the
perturbed; and that we, learning them and being partakers of the true
computations of nature, might imitate the absolutely unerring courses
of God and regulate our own vagaries.”


2. EUDOXUS.

[Sidenote: Eudoxus 408 B.C. to _c._ 355 B.C.]

With words like these ringing in his ears, Eudoxus went from the
Greek philosopher to the Egyptian priest, and studied “the courses of
intelligence in the heaven.” Legend says that the sacred Egyptian Bull
licked his garment, and the priests no doubt were encouraged by this
omen to divulge their secrets to a person so highly favoured by the
gods. They prophesied that he would have a short but very illustrious
life.

After a year, or perhaps more, spent in Egypt, Eudoxus returned to his
own city, set up an observatory of his own, received pupils, and worked
out an exceedingly ingenious and original planetary scheme. He did not
accept (if he knew of them) the risky theories of the Pythagoreans as
to Earth’s motion, but assumed a central stable earth, round which
circled the stars and the seven planets, according to the teaching of
Plato and the general belief among educated Greeks of his day. But
Egyptian observation and Greek geometry enabled him to describe for the
first time the complicated movements of the planets, and to represent
them by an imaginary mechanism.

This was a series of spheres, or hollow balls, fitting inside one
another, and gradually diminishing in size like the ivory boxes of a
Chinese puzzle, or the coats of an onion. Their size was stupendous,
for the outer one, which contained all the rest, was nothing less
than the sky we see, and was encrusted all over with stars. Of the
inner smaller spheres, one bore, fixed in it like a jewel set in a
ring, the sun; and six others bore, in the same way, the moon and
the planets, one in each. All these hollow spheres were symmetrically
placed so that all centred in a single point, and at this point was a
solid sphere, exceedingly small in comparison, which was the earth. The
star sphere, without moving from its place, rotated round this central
Earth, and this caused the diurnal motion that we see in the stars.
Each planet-bearing sphere rotated also, but the special characteristic
of Eudoxus’ system is that each of these was surrounded by its own
complete set of spheres, bearing no planet, but all attached together,
the poles of one sphere resting on the surface of the next, and moving
with different speeds, in different directions, and with differently
inclined axes: these motions being all communicated to the innermost
sphere on which the planet was fixed, the net result was the movement
of the planet as we see it in the sky. Each planetary set was quite
separate from the rest, and did not interfere with their movements,
although each set was enclosed within the next larger. Since all the
planets have a diurnal motion like the stars, as well as their own
proper motions, each set had to be provided with a sphere which moved
exactly like the great all-enclosing star sphere.

Thus, the sun had one sphere turning like the star sphere, and within
this was a second, on which the sun was fixed, which turned round in
a year, in a west to east direction. The sun, carried along by the
combined motion, travelled through the sky with the daily and yearly
motions, as we see them.

[Illustration: Fig. 19. The spheres of the sun in the system of Eudoxus.

The outer sphere turns on its axis _A A_ in a day and night; the inner
on its axis _a a_ in a year, in the opposite direction.]

The planetary spheres were much more difficult to arrange. Eudoxus used
four spheres for each, and these had in every case to be carefully
adjusted to the very different periods and amplitudes of the planetary
oscillations. It must be confessed that the scheme failed with the
difficult case of Mars, and was not quite satisfactory with Venus, but
it represented remarkably well the movement—so far as then known—of
Sun and Moon, Saturn, Jupiter, and Mercury. It was certainly a feat
for those days, whether we consider it merely as the solution of a
mathematical problem, or as an embodiment of astronomical knowledge.
The periods of the planets as known to Eudoxus, stated in round numbers
only, are given in the following table. They are taken from Simplicius,
who describes the system of Eudoxus, but as in the so-called Papyrus
of Eudoxus the synodical revolution of Mercury is given as 116 days,
the same as the modern value, Eudoxus may have had much more exact
data. It will be seen that his synodic period for Mars is the only one
which is totally wrong, and the large error is difficult to explain.

                                    _Modern     Zodiacal       Modern_
    _Planet.   Synodic Period.       Value.      Period._[34] _Value._

     Mercury    110 days             116 days     1 year        1.0 year
     Venus       19 months           584  ”          ”          1.0  ”
     Mars       8 months, 20 days    780  ”       2 years       1.88 ”
     Jupiter     13 months           399  ”      12   ”        11.86 ”
     Saturn      13 months           378  ”      30   ”        29.46 ”

------------------------------------------------------------------------
[34] The period in which a planet is seen to revolve round the zodiac,
and return to the same star, varies greatly, because complicated by
its retrograde movements; but if the average of a sufficient number of
periods be taken, it coincides for Mercury and Venus with the sidereal
year; for Mars, Jupiter, and Saturn, with the period in which each is
actually revolving round the sun (its “sidereal period”).
------------------------------------------------------------------------

It is disappointing, after the splendid hypotheses of the Pythagoreans,
to be back again on a central stationary Earth among mechanical
contrivances for moving the heavenly bodies, which remind us of
Anaximander’s series of hemispherical heavens and heavenly wheels, but
at least the earth is spherical, owing to the Pythagoreans, and the sky
extends like a sphere all round, and we shall never have a flat Earth
or a hemispherical sky again among the Greeks. We do not know whether
Eudoxus regarded his spheres as convenient mathematical abstractions
only, or whether he reasoned that the stars were evidently set in an
invisible uniformly rotating sphere, and Plato considered this kind
of movement the most suitable for all heavenly bodies; that therefore
he would try whether a series of similar spheres interacting on one
another would account for the complicated motions of a planet, and
finding that they would, taught that they must truly exist. In any case
the basis of his system was a detailed knowledge of planetary motions
hitherto unapproached by the Greeks, and its chief merit was that it
challenged comparison with the skies.


3. CALIPPUS.

[Sidenote: Calippus _c._ 330 B.C.]

The challenge was soon taken up, for twenty or thirty years later one
of the pupils of Eudoxus, Calippus of Cyzicus, undertook to improve the
system. The defects in the theories of Mars and Venus had evidently
been discovered, for Calippus added another sphere to each of these,
as well as one to Mercury, which would be quite enough to bring the
theories into better agreement with the facts.

With regard to the sun and moon, Calippus had paid special attention to
their movements, for he made an improvement in the old luni-solar cycle
of Meton, to which we shall return later. Eudoxus had ignored a very
important fact discovered by Meton and Euctemon about B.C. 430, viz.:
that the seasons are of unequal length, showing that the sun takes
unequal times to pass over the four arcs of his orbit lying between the
four points of the vernal and autumnal equinoxes and the summer and
winter solstices. “Why,” exclaims a later writer[35] “are there unequal
numbers of days in the four seasons, seeing that the course of the
heavenly bodies must be regular, not being swayed by human passions or
affairs?”

------------------------------------------------------------------------
[35] Geminus.
------------------------------------------------------------------------

Calippus considered this question very seriously, and made a careful
determination of the length of the four seasons. It seems at first
sight impossible to reconcile their inequality with uniform circular
motion of the sun round the earth, but he found that he could do it by
adding two more spheres to the sun’s set, rotating uniformly but so
arranged that their motion, added to the others, would result in an
actual velocity in the sun itself varying just in the way required by
the facts. The same had to be done for the moon, for the same reason,
so the number of spheres, which Eudoxus had made twenty-seven, was
brought up to thirty-four (including the star sphere). The varying
velocity of the five planets had not yet been perceived.[36]

------------------------------------------------------------------------
[36] This varying velocity is due to the fact that all celestial
orbits are not true circles, but ellipses, which was first discovered
by Kepler (1609 A.D.).
------------------------------------------------------------------------


4. ARISTOTLE.

[Sidenote: Aristotle B.C. 384-322.]

Calippus went up to Athens about 330 B.C. to lay his scheme before the
great master, Aristotle, and it had his cordial approval. But Aristotle
definitely accepted the spheres as things having a concrete existence,
for he says (_De Cœlo_ II, 12) that we must regard them as heavenly
bodies like the stars and planets, and that they are composed of the
same celestial stuff.

He made one change, when incorporating the system in his scheme of
the Universe. He was not satisfied that each set of spheres should
work quite independently of the rest, and thought that the outermost
sphere of stars ought to communicate its motion to those below
(_i.e._ nearer Earth); and no doubt it did seem rather clumsy to
have a separate sphere in every set rotating in exactly the same
manner as the star sphere. But how could the impulse be communicated
without disturbing the other movements? Aristotle introduced below
each set another set of “unrolling” spheres, as he called them, which
successively neutralized the rotations of all spheres in that set
except the one with diurnal rotation, hence this movement alone was
communicated to the set next below. This seems, however, more clumsy
than the defect it was intended to remedy. Aristotle was perhaps led to
it by his wish to give greatest importance to the star sphere; and if
so, he acted on the principle which he blamed in the Pythagoreans, of
making deductions not from things as they are seen, but as, according
to his own ideas, they ought to be.

For indeed Aristotle, in spite of his own doctrines, and the great
impulse which he gave to truly scientific methods of observation and
experiment, could not rise altogether above the prejudices of his age,
and consequently his Cosmos is a curious mixture of sound reasoning,
based on observation, and of metaphysics, the latter predominating. For
instance, it is only at the end of his second book _On the Heavens_,
after he has “proved,” from purely metaphysical reasons, that Earth
must necessarily be spherical and at the centre of the World, that he
adds in support of his assertions the fact that the curved line of
Earth’s shadow seen on the moon during eclipses is always round, that
stars vary in visibility as we change our horizon, and that astronomers
say that the celestial phenomena occur as they would if Earth were at
the centre of the World.

Nevertheless, Aristotle’s teaching had so overwhelming an influence,
not only throughout this epoch, but in the age of Dante, and the latter
was so greatly influenced by him, both directly and indirectly, that
it is exceedingly interesting to know his ideas about the Cosmos. We
find them in the two books _On the Heavens_, in the _Meteorology_, the
_Metaphysics_, and some other works. A special treatise on Astronomy,
to which he refers[37], is unfortunately not extant.

------------------------------------------------------------------------
[37] _De Cœlo_ II. 10.
------------------------------------------------------------------------

The form of the Universe, Aristotle says, must be a sphere, because a
sphere is the most perfect of solids and a solid is more perfect than a
surface or a line, because it is in three dimensions, and three means
completion, perfection.[38]

------------------------------------------------------------------------
[38] Thus, (he adds) time also is threefold, for we have Beginning,
Middle, and End. Therefore we apply three to Divine things, and also
in common speech we call two “both,” and only say “all” when we reach
three, following Nature’s law. The Pythagoreans say “The all and all
things are bounded by the number three.”—_De Cœlo_ I. 1.
------------------------------------------------------------------------

The Universe had no beginning, and will have no end; and this
conclusion, drawn from reasoning, is supported by the belief which all
have who believe in gods, “whether Greeks or not Greeks,” that the
gods, who are immortal, live in the highest heaven, which is therefore
also immortal; and by the fact that no one, throughout the ages, so far
as we know, has ever seen any change in it.

But it is of finite dimensions, for no infinitely great body could
rotate in a finite time; and it is the only universe which exists or
ever can exist: outside is neither space, nor void, nor time. For space
is that which is or may be occupied by matter, and time is the measure
of motion occurring in matter, and no matter exists or can exist there.
Therefore that which exists there is not in space nor is altered by
time, but lives for ever the best and the self-sufficing life (_i.e._
the purely spiritual).

As matter has three dimensions, so motion is of three kinds: viz. (1)
in a straight line down, that is, towards the centre of the World; (2)
in a straight line up, that is, towards the circumference; (3) in a
circle round the centre. Thus simple heavy bodies such as all kinds
of earth, have a simple motion downwards; simple light bodies such as
fire, move upwards; and when they reach their respective goals they
remain where they are, unless disturbed by external force—earthy things
on the earth, fiery vapours in the upper atmosphere. Composite bodies
have composite motions, the motion proper to the predominant substance
predominating. But for the heavenly bodies the only possible motion is
in a circle, where there is neither beginning nor end, no goal and no
limit, hence this motion is eternal.

Thus Aristotle solved for himself the problem of the early
philosophers: how the stars in the sky remain there, for ever circling
round us, and never falling to the ground. There is no need, he says,
to assume an Atlas to support the sky on his shoulders, as in the old
myths, nor a whirlwind such as Empedocles suggested, nor a Soul of the
World, as Plato said; for the heavenly bodies are not heavy things
like Earth to need support, and they are not moved by force, but are
eternally in motion from the nature of their being.

In the same way he disposes of the difficulty of supporting Earth,
having first “proved” that because there is an ever-circling spherical
Heaven, there must also be an ever-resting spherical central Earth;
there must be its opposite, the ever upward-striving Fire; and there
must be the intermediate pairs of opposites, Air and Water. It is
indeed, he says, a strange thing, and one to set any thoughtful man
thinking, that the smallest clod of earth, when thrown up into the air,
immediately falls down, and presumably would never stop falling if the
earth were suddenly removed from beneath it; yet here is Earth herself,
so large and heavy, not falling, but remaining steady in one place. But
the explanations given by philosophers are more difficult than the fact
they seek to explain. Xenophanes of Colophon said that the earth roots
in the infinite, which simply saved him the trouble of considering
further; others that the earth rests on water, which is our oldest
tradition, said to be derived from Thales; but on what then does water
rest and how can water, which is lighter than earth, support it? Do we
not see that even small pieces of earth sink in water, and larger ones
still more quickly? Anaximenes, Anaxagoras, and Democritus said that
Earth rests on air, through her flat shape, as a leaf can float on the
wind, and they added that the air cannot escape because the flat earth
fits close down upon it, like a lid, which is also the reason that
it can support the earth, because it is compressed, and they brought
forward many proofs to show that air, when compressed and still, can
support great weights. Others, like Anaximander, said that Earth rests
because she is in equilibrium, for there is no reason why she should
move in one direction rather than another. But all earthy things (says
Aristotle) do not merely remain at the centre when there, they move
thither whenever displaced. They are not suspended like a hair which
is powerfully but uniformly stretched, and so never breaks, nor like
a man who is equally hungry and thirsty, and has meat and drink at
equal distances from him and therefore starves.[39] No, the truth is
that Earth, and every particle of Earth, tends naturally towards the
centre of the Universe, and rests when at its goal. We must remember
that on every part of the sphere of Earth, heavy bodies fall vertically
to its surface, showing that it is not to the surface in general that
they fall, but exactly to the centre, which is also the centre of the
Universe.

------------------------------------------------------------------------
[39] _Par._ iv. 1-3.
------------------------------------------------------------------------

Of course it was no solution of the mystery, but only moving it a
step back, to say that the stars circle because it is their nature to
do so, and heavy bodies fall to Earth because that is their nature.
But the interesting point is that the Greeks did reason about these
two motions, and compare them; that they clearly grasped the fact
that “weight” simply means a tendency to move, and that the motion
of falling bodies at Earth’s surface is invariably towards Earth’s
centre, accelerating as it appproaches the surface (_De Cœlo_ I. 8).
It is only the fresh mind of a little child, or of a really intelligent
man, which is forcibly struck by the mystery of everyday sights, such
as stones falling, and stars _not_ falling but eternally moving in the
sky. The force which makes bodies move towards one another we still
call “heaviness,” _i.e._ gravity, and the mystery of its ultimate
nature and mode of action is still unsolved. It is so weak and so often
complicated by other forces that, except in very delicate experiments
or with the mind’s eye, we can only see it in action when bodies fall
to the ground; and thus Nature guarded for centuries the secret that
every tiny particle on the whole earth attracts every other, and also
the earth itself, as surely as the earth attracts them. The further
grand secret concerning this force Eudoxus had unwittingly set out
to discover, with his planetary periods learned from the Egyptians,
and his three motions of the moon. For when this study was far enough
advanced, the necessary data were at hand for Newton, as he pondered
the mystery which had baffled Greece; and he was able, from the
moon’s motions, to verify his guess, that even the heavenly bodies
are in truth always falling, falling, towards one another, exactly as
Aristotle’s “smallest clod of earth” fell to the ground.

From the theory of the three simple motions, it obviously follows that
Earth must be at the centre of the world, that her particles must be
arranged in a spherical form round the central point, also the sphere
must be at rest.

But all are not agreed about this, says Aristotle. All who consider the
Universe finite say Earth is at the centre; but the philosophers in
Italy, the so-called Pythagoreans, on the contrary, say that in the
centre is Fire, and that Earth, which is one of the stars, is in motion
round the centre, and so causes day and night. They also assume a
Counter-Earth, merely from pre-conceived ideas, not from observation of
facts. And some agree about the Central Fire, from pre-conceived ideas,
because they think that the noblest should have the noblest place: fire
is nobler than earth, and boundary nobler than what is bounded, and
circumference and centre are both boundaries; therefore (they say) Fire
and not Earth is at the centre. Moreover, the Pythagoreans say that the
most important part of the Universe is the best guarded, and that the
centre is such a part, and they call it the Watch Tower of Zeus.

To these metaphysical reasons Aristotle replies that the centre is not
a true boundary, it is rather an end than a source, it is the material,
the limited, while it is the circumference which limits, encloses, and
gives the form. Besides, the centre of a thing is not necessarily the
centre of its being; as with animals the centre of their life (meaning
the heart) is not the centre of their body. So the philosophers need
not disturb themselves to put Earth out of her local centre, but they
would be wiser to examine that other centre of the Universe (meaning
the sun), and find out what is its nature and its place, for it also is
a point of origin, and noble.

He continues “Some also assert that though Earth is at the centre,
it is wound and moving round the axis which is extended through the
Universe, as is written in the _Timaeus_.” Plato’s actual words in the
_Timaeus_ will not bear this interpretation, as we have already seen
(p. 85). It is a little surprising that Aristotle does not mention the
names of Ecphantus the Pythagorean and Heracleides of Pontus in this
connection, since the latter was his contemporary, and perhaps the
other also, for they are mentioned together as teaching the doctrine
of Earth’s rotation on her axis.[40] Also Aristotle seems hardly fair
to either this or the Central Fire theory, in that he only answers the
metaphysical reasons of the Pythagoreans, and omits to mention that
either would unify the diurnal celestial motions in a much simpler way
than all his “unrolling” spheres. If he had not especially mentioned
that Earth’s motion was supposed by the Pythagoreans to cause day and
night, we should be inclined to think that he did not understand that
the period was twenty-four hours, and that its effect would be to
produce the apparent diurnal rotation of all the heavens.

------------------------------------------------------------------------
[40] See p. 75, note.
------------------------------------------------------------------------

The passage, however, has been a cause of endless controversy from
the earliest commentators of Aristotle to the present day, and such a
thorny question would have been avoided altogether in this book were it
not that it is actually quoted by Dante in the _Convivio_.

As to the size of the earth, Aristotle held that it was not a large
sphere, and small when compared with the stars. For, he says, if we
take quite a short journey to north or south, our horizon changes
markedly, so that the stars above us look quite different, and we do
not see the same stars; for some which are well seen in Egypt and near
Cyprus are not visible at all in northern parts, and those which in the
north are always in the sky, set when we go south. And therefore, he
adds, those who say that the regions near the Pillars of Hercules are
connected with India, so that the ocean is one, are not saying anything
altogether incredible; and their proof is that there are elephants
both in the extreme east and the extreme west. He does not mean,
evidently, that there was no sea at all between, but only that one
could quickly travel from one to the other, always going west: there is
no immense stretch of land or sea between west Africa and east India,
nor are they the extremities of a flat disc-like earth. Aristotle
tells us, moreover, that the mathematicians, who have tried to measure
the circumference of the earth, find that it is about 400,000 stadia.
This is the first time we hear of an attempt to measure the earth, but
unfortunately we do not know what stadium was used, nor what was the
method employed.

       *       *       *       *       *

Aristotle’s Cosmos is arranged as follows:—

Upon the central spherical Earth rests water, and above this is air,
but these intermingle more or less, and are not sharply divided; in
the same way, though fire rises highest of the four elements, there is
not a distinct sphere of fire, but the higher part of the atmosphere
is chiefly composed of it. It is in this upper fiery atmosphere that
shooting stars are produced: hot and dry exhalations rising from Earth
take fire there, but are quickly consumed. Comets have their origin in
the same place, when large masses of vapour rise and are directly below
the sun (had the Greeks noticed that comets’ tails are always streaming
away from the sun?). Aristotle also explains that the Milky Way is
formed from these constantly-rising vapours, but under the influence of
the stars, for it always has the same position amongst them, and that
is where the most numerous and brightest stars congregate.

Thus within and below the fiery atmosphere constant changes are taking
place, and all things are perishable, but as soon as we reach the
lowest of the heavenly spheres, the moon’s, we enter another world.
All is changeless, eternal, divine. Motion is in circles, space is
filled with ether, the heavenly bodies as well as their spheres are of
an ethereal substance.

The Pythagorean idea of music made by the spheres, Aristotle dismisses
as very pretty but unfortunately not true. For if in truth these
immense spheres made a sound as they moved, even if we could not hear
it (as they said) we should feel it, for even earthly thunder bursts
rocks asunder! And there is no reason why they should make any sound,
for nothing moves out of one place: the spheres are simply rotating,
which is the natural movement for a sphere, unless it rolls along,
which they are not doing. If nature had wished the spheres or the stars
and planets to move forward, she would not have treated them worse
than terrestrial animals, in giving them no limbs by which they could
progress! The stars and planets have no motion themselves of any kind,
but are simply carried along by their rotating spheres, as we can
plainly see by the moon turning always the same face towards us: hence
they make no more noise than a ship’s mast set in a ship, or the whole
ship as it glides down a river.

Stress is laid both by Plato and Aristotle on this absence of any
motion of translation in the heavenly bodies and their spheres;
both insist that a movement of rotation, in which the moving body
continually occupies the same place, is the only movement existing in
the heavens. One wonders whether the spheres of Eudoxus suggested or
resulted from this idea.

Aristotle does not enter into detail about the separate planetary
motions, in any extant work, but explains as the general principle that
the outermost, the prime movement of the whole universe, is simple,
and the most rapid, while the inner are complex, slower, and in the
contrary direction; so that the planet nearest to the prime movement
(Saturn) is longest in making his own revolution, because most affected
by it, and the others less so in proportion to their distance. He
refers his readers to the mathematicians, and quotes the Egyptians and
Babylonians as having furnished satisfactory proofs of the relative
positions of the planets, by such observations as occultations of
other planets by the moon, which show that she is below them (_i.e._
nearer to us). The passage is quoted by Dante[41], in which Aristotle
describes how he himself once saw an occultation of Mars. “When the
moon was a half sphere, she passed beneath Mars and he disappeared
under her dark side, but came forth again on her bright illumined side.
And the same kind of thing,” he adds, “is reported to happen with the
other planets also, as those tell us who for a vast number of years
have made observations, viz. the Egyptians and Babylonians.”

------------------------------------------------------------------------
[41] _Conv._ II. iii. 59-65.
------------------------------------------------------------------------

There is one point which is elaborately discussed in the _De Cœlo_,
which seems very curious to us, but the main point must be noted here,
since it is of some interest to the Dante student. Aristotle tells
us that he considers the sphere of the Universe to have a top and a
bottom, and that the Pole which is not seen by us (the south) is at the
top. One cannot help thinking that Dante had this in mind when he chose
the southern hemisphere for the mount of Purgatory, whither, after all
their mistakes and wrong-doing on this underside of the earth, souls go
to purify themselves on the upper side, under the stars of the southern
pole.

In his book on metaphysics, Aristotle gives a very brief sketch of the
spheres of Eudoxus and his own “unrolling” spheres; and says that all
these planetary movements prove the existence of Essences, eternal
and immoveable themselves, who cause these movements. And it has been
handed down to us in a mythical way, from the most ancient teachers,
that these eternal Essences are gods. Above all these must be a First
Mover, the Primum Movens Immobile, who is one, eternal, and enjoys
for ever the kind of existence which we only experience in our best
moments. Upon this First Mover depend the whole heaven and all nature.


5. ARISTARCHUS.

With a system of revolving spheres accepted by the mathematical
astronomers, and sanctioned by the great philosopher Aristotle, it
may be thought that we are within sight of our goal, the system
of Greek astronomy which was to dominate the scientific world for
many centuries, including the age of Dante. But so exacting had
the careful observers become that the system of Eudoxus must be
completely transformed, by aid of two quite new hypotheses, before
it would satisfy their demands. Also, about half a century after the
consultation of Calippus and Aristotle in Athens, a strange new theory
was propounded, the boldest and strangest of all.

[Sidenote: Aristarchus _c._ B.C. 281.]

Nearly two thousand years before Galileo was summoned before the
Inquisition, and forced to recant upon his knees his “most damnable
heresy” that the earth goes round the sun, Aristarchus of Samos was
accused of impiety by his countrymen for the same crime. But he met
an even sadder fate than Galileo—neglect. His daring scheme was
almost ignored by his contemporaries, and but for a casual mention by
Archimedes and by Plutarch, we should know nothing about it.[42]

------------------------------------------------------------------------
[42] It is also mentioned in a compilation of philosophers’ opinions,
probably made in the fifth century A.D. by Stobæus, who is very likely
quoting Plutarch.
------------------------------------------------------------------------

He was, however, very famous as a mathematician, and also as an
observer. Ptolemy quotes his determination of the summer solstice of
the year b.c. 281, and this tells us the date at which he flourished.
He was renowned for a very ingenious method by which he tried to
discover how much further from us the sun is than the moon. When the
moon is half full the angle sun-moon-earth is a right angle, and if
the angle sun-earth-moon be measured, by pointing the astrolabe first
to sun and then to moon, the third angle, at the sun, may be computed,
and then the ratio sun-earth to moon-earth will be known. The method
is perfect theoretically, and if the sun were comparatively near, say
about ten times the moon’s distance, it would be practicable; but the
distance is really so much greater that the angle at the sun almost
vanishes, and a very small error in estimating it causes an error
equal to many millions of miles in the result. It is also impossible
to determine from looking at the moon the exact time when the division
between light and dark is a straight line. Aristarchus made the angle
at Earth 87° instead of 89° 50′, and this gave the sun a distance of
about 19 times as far as the moon, instead of 400 times, which is the
true value.

[Illustration: Fig. 20. Method of Aristarchus for finding the distance
of the sun.]

The foolish fad (as they thought it) about Earth’s motion, held by this
otherwise great man, is described quite clearly by the two writers
above-mentioned. He suggested that the stars might be immoveable, and
Earth be turning on her axis at the same time that she moves in a
circle round the sun. Moreover realizing all that this implies with
regard to the immense distance of the stars, he said that the circle
in which Earth revolves round the sun, compared with the sphere of the
stars, is as the centre of a sphere compared with its circumference.
That is, not only Earth, but Earth’s whole orbit, shrinks to a point
when compared with the infinite distance of the stars.

We have unfortunately absolutely no information as to the way in which
Aristarchus was led to these remarkable truths, and can only make
conjectures from what we know of his times. Evidently the Central
Fire theory was a suggestive step, and so was another theory which
was afloat about this time, and has been called the “Egyptian system”
on the authority of Macrobius in his commentary on Cicero’s _Dream of
Scipio_. No one really knows where it arose, but it is ascribed with
much probability to Heracleides of Pontus. According to this, the
two planets Mercury and Venus circled round the sun, and all three
together circled round Earth, which still remained the centre of the
Universe and of the other celestial motions. It was an idea which might
have occurred to any unprejudiced observer, since the oscillations of
Mercury and Venus from side to side of the sun are more striking than
their movements through the stars. They never go far from him in the
sky, like the other planets, and seem to belong to him.

Further, the clear understanding of the periodic motions of Mars,
Jupiter, and Saturn, and the accurate observation which had been
introduced by Eudoxus, must have revealed the fact that the loops in
the orbits of these planets are connected with the apparent movement of
the sun; and the varying brightness (especially noticeable with Mars)
is inconsistent with the assumption of unvarying distance from Earth.

The great importance of the sun, above all the other planets, had of
course always been recognised, and it is possible that Aristarchus
was struck by an unconscious suggestion in Aristotle’s advice to the
Pythagoreans to examine the nature and place of the sun, “that other
centre of the Universe,” for that was also a point of origin, and
a noble one.[43] His own work, too, would lead him to attribute a
commanding position to the sun, for as it was nineteen times as distant
as the moon, it must also be nineteen times as large (since they appear
equal), so he must have felt certain that it was a very great size,
probably much the largest of all bodies in the Universe.

------------------------------------------------------------------------
[43] See page 101.
------------------------------------------------------------------------

It was the grandest and truest of all the Greek astronomical theories.
But it was not accepted, it was hardly even discussed, and we can
scarcely be surprised at this. Such an improbable theory needed
many more convincing proofs than Aristarchus could bring forward.
Observation, calculation, comparison of theory with facts, this was
what was needed before safe ground could be won for belief, and in
this Eudoxus was a true pioneer. But freedom of thought and courage in
imagination is needed also in science, and Aristarchus seems to have
been almost the last to possess this.

[Sidenote: Seleucus B.C. 160.]

[Sidenote: Aryabhata born A.D. 467.]

A certain Babylonian, named Seleucus, who lived about B.C. 160, perhaps
on the Tigris, and an Indian astronomer, Aryabhata, of the fifth
century A.D., both taught that Earth turns on her axis, but Aristarchus
stood alone in suggesting that she also has a movement of revolution
round the sun. The possibility of Earth’s motion was alluded to but
seldom by classical and mediæval writers, and then almost always as a
foolish fancy hardly worth discussion;[44] until at last Copernicus,
hardly daring to publish his bold idea in sixteenth century Europe,
for fear of persecution, sought and found among the followers of
Pythagoras, and in Aristarchus of Samos, kindred spirits with his own.

------------------------------------------------------------------------
[44] Indian astronomers also refused to accept the doctrine of
Aryabhata. Varâha Mihira (sixth century A.D.) says:—“Others maintain
that the earth revolves and not the sphere: if that were the case,
falcons and other birds could not return from the ether to their nests.”
------------------------------------------------------------------------


6. THE SCHOOL OF ALEXANDRIA.

The spheres of Eudoxus would not work. The system was already
overladen, and more variations in velocity were becoming known.
Observation shows, too, that the planets, especially Mars and Venus,
vary greatly in brightness, in regular periods which correspond with
their movements, and this could not be accounted for by any possible
number or arrangement of spheres if all were to remain concentric to
Earth, so that every planet remained always at a uniform distance. Yet
Aristotle had said that Earth must be at the centre of the Universe.
The new philosophers of the Stoic school agreed with him, and among
mathematicians only Aristarchus dared to disagree.

But they were not long at a loss. The homocentric spheres[45] were
thrown aside, and during the third century two new hypotheses were
suggested (beside that of Aristarchus), and although we do not
certainly know by whom, there is little doubt as to the place in which
they originated. By a strange fate, Egypt, the home of astronomy many
centuries before, became the seat of the latest, most brilliant, and
most successful astronomical school of ancient times, and the knowledge
won there in the five centuries between B.C. 300 and A.D. 200 spread,
following in the wake of Alexander’s conquests, over the whole of the
civilized world.

------------------------------------------------------------------------
[45] Spheres all centring in one point.
------------------------------------------------------------------------

It was a purely Greek school, however. Greece lost her independence
under Alexander, and was finally crushed by Rome in 146 B.C., but never
was Greek learning and culture so much honoured and sought after as
in this age. In Egyptian Alexandria, Greek men of science found a
welcome, and opportunities of research which did not exist in any other
place in the world. In the Museum, founded and liberally endowed by
the royal Ptolemies, was a great library whose custodians were bidden
to obtain every book that had ever been written, and it is said that
when any stranger arrived with a new book it was taken from him and
copied for the Museum, and the copy returned to the owner. Within the
great marble colonnaded building were lecture-halls, and reading rooms,
and laboratories; there were gardens for botanists and zoologists, and
observatories for astronomers. These astronomers were all Greeks, and
though now living in Egypt they do not seem to have learned anything
more from the Egyptians. Perhaps the priests resented the intrusion,
and kept their secrets jealously to themselves; perhaps Eudoxus and
his immediate followers had learned all they had to teach. This seems
the more probable because, although the Greeks of this age did use
Babylonian records of eclipses to form a lunar theory, they complained
of the insufficient accuracy of all available planetary records.
Moreover, they were not hindered from learning astrology: the sacred
books of the Egyptians which taught its principles were translated into
Greek about 300 B.C.; but it was always treated by them as quite a
separate branch of study. Their geometrical methods were entirely their
own. They introduced a system of notation which greatly simplified
calculation[46]; their discovery of the principles of spherical
trigonometry inaugurated a new era in astronomy; and they invented a
new class of astronomical instrument.

------------------------------------------------------------------------
[46] Mahaffy, _The Progress of Hellenism in Alexander’s Empire_, p.
119.
------------------------------------------------------------------------

We know what these instruments were like, and it is even possible to
give an illustration; for, from descriptions in Ptolemy’s _Almagest_,
we find that the “well-made copper circles,” the gnomons, and the
celestial globes, which were set up in the Square Portico of the
Museum, were of the same pattern as instruments which existed in Pekin,
in the ancient observatory on the ramparts, until they were looted by
the Germans during the late Chinese war. The Alexandrian instruments
were not supported on their stands by beautiful bronze dragons, but on
the other hand the circles were more accurately divided, which after
all was of more importance from the astronomers’ point of view. Fig. 21
gives a general view of the Pekin Observatory, and Fig. 22 one of their
astrolabes dating from the 13th century A.D.

At first glance there seems to be here absolutely nothing like our
modern observatories. Ancient and mediæval astronomers had indeed no
telescopes, being ignorant of the properties of lenses: therefore they
were unable to study the features of any heavenly body except the
moon, and they had no way of finding out anything about their physical
constitution; but they had many ways of measuring their distances
and motions, and even the angular sizes of sun and moon, and their
instruments were the forerunners of our sextants, micrometers, and
transit instruments, our chronometers and sidereal clocks.

[Illustration: PEKIN OBSERVATORY. [_To face p. 114._

_From a photograph taken in 1888, and published in the “Bulletin de la
Société belge d’Astronomie”._]

The gnomon has been already described[47], and it was one of the most
valuable instruments used by the Greeks. The Pekin gnomon at the right
of figure 21 was more than 40 feet in height, and on the top had a
little plate of copper which was pierced by a hole as fine as the eye
of a needle: the observations made with this were much more exact than
observations of the end of the shadow, which must always be vague, and
the Chinese records of the sun’s movements made with this instrument
between 1270 and 1280 A.D. are of great value in modern research.
Ptolemy explains that his gnomon was made accurately vertical by the
use of a plumb-line, and that one way of testing the level of the
surface on which the shadow fell was to flood it with water.

------------------------------------------------------------------------
[47] See p. 26.
------------------------------------------------------------------------

Clepsydras, or water-clocks, were used by the Greeks, and many kinds
of sundials for telling the time by day. Tables were also made of the
risings of bright stars which served for clocks by night.

The instrument in the middle of the platform is a quadrant, and beyond
this on the left is a large celestial globe, which, however, only
dates from the Jesuit missionaries of the seventeenth century. Ptolemy
says that his globe was made the colour of the night sky; Sirius being
marked in his proper place, all other stars were placed relatively to
him, and in their own colours as nearly as might be; the Galaxy was
drawn, and the figures of the constellations outlined. The globe was
arranged to turn on either the poles of the ecliptic or of the equator;
circles of wood represented the horizon and meridian, and the pole
could be arranged at any altitude according to the latitude of the
place.[48]

------------------------------------------------------------------------
[48] _Almagest,_ Bk. viii.
------------------------------------------------------------------------

But perhaps the most interesting are the astrolabes, and these owe
their origin to the Greeks. The essential part of any instrument for
determining angular distances is a divided circle and a pointer: the
pointer is directed first to one object then to another, and the angle
between them is then read off on the circle. In the astrolabe, the
pointers themselves were also circles, provided with little perforated
rods for “sights.” (These are not visible on the instrument in Fig.
22, and have probably been broken off.) There were two fixed circles,
set in the plane of the ecliptic and perpendicular to it. Three other
circles could be rotated round the poles of the ecliptic. One of these
was directed (by means of the sights), to some body whose position
was already known, another to the body whose position was to be
ascertained, and the angle between them was read off on the ecliptic
circle; on the third the angular distance north or south of the
ecliptic circle could be read. This last and the ecliptic circle were
both divided into 360 degrees, and as many fractions of a degree as
space and skill would allow.

The equinoctial astrolabe was similar, but the fixed circle was in the
plane of the equator, instead of the ecliptic. One of each of these is
seen in the view of the Pekin Observatory.

But how did the old astronomers know how to find the ecliptic and the
equator in the sky, and set their circles in those planes? This they
did by means of the sun’s motion. The gnomon told them the day of
the equinox (see p. 25), and on that day the sun was in the equator:
therefore, if a circle was set up so that the shadow of the upper part
fell symmetrically upon the lower, with a little line of light each
side, it must be exactly in the plane of the equator. In the Square
Porch such a circle was erected, a large one of copper, and when once
correctly adjusted it was a standard plane, and also showed the date of
the equinoxes, as accurately as the gnomon itself. Since the ecliptic
is the path of the sun as seen in the sky, it is obvious that it could
be determined from a number of different observations of his position
at different times of the year.

[Illustration: A PEKIN ASTROLABE OF THE 13TH CENTURY, A.D. [To face p.
116

_From a photograph taken in 1888, and published in the “Bulletin de la
Société belge d’Astronomie”._]

Finally, accurate solar tables were drawn up, showing the sun’s
position in the sky in degrees for different dates, and then from these
it was possible to find the places of planets and stars. They could
not of course be compared directly, but the position of sun and moon
were compared during the day, when both were in the sky, and then after
dark the planets and stars were compared with the moon, allowing for
her motion among the stars in the meantime. Or secondly, when the moon
was eclipsed, and therefore known to be in the ecliptic and exactly
opposite the sun, the places of stars could be found directly.

This very brief description will give some idea of the chief
instruments and methods used, and when we see how very rough and
elementary they were, and remember that the Greeks had to work out
their observations without algebra, or decimal notation, we are amazed
at their results, and their far-reaching ambitions.

[Sidenote: Eratosthenes B.C. 276-194.]

Already in the very early days of the Museum, Eratosthenes, a
celebrated geographer, made a bold attempt to utilize observations
of the sun measuring the size of the earth. It was known that in
Syene (the modern Assuan) on the day of the summer solstice at noon
no shadows were thrown, and the bottoms of wells could be seen:
evidently therefore the sun was in the zenith. Eratosthenes found
that the sun’s distance from the zenith in Alexandria at noon on
the same day was 7° 12′, or one-fiftieth of the circumference of
the heavenly sphere, consequently the two towns must be distant
from one another (assuming them to be nearly in the same meridian)
one fiftieth of the circumference of the earth. The distance from
Alexandria to Meroe was known, and from Meroe to Syene had been paced
by the king’s professional pacers; the whole was 5000 stadia. 50 times
5000 = 250,000. The figure always quoted by the ancients is however
252,000. If the stadium used by Eratosthenes was the measure generally
used for long distances which have been paced, this estimate is equal
to 24,662 miles, only about 200 miles less than the modern value. It
was partly by luck that Eratosthenes got such a good result, for he was
evidently only working with round numbers, and the extra 2000 stadia
seem to have been added in order to make one degree equal to exactly
700 stadia. But in any case it was a highly creditable performance.

[Sidenote: Euclid _c._ B.C. 300.]

[Sidenote: Apollonius _c._ B.C. 270.]

There were celebrated mathematicians and geometers at Alexandria, whose
work was most useful to astronomy, such as Euclid, and Apollonius of
Perge. The latter is specially mentioned by Ptolemy in connection with
the new theory of “moveable eccentrics,” which was invented to account
for the varying brightness of the planets, as well as their peculiar
movements.

Fig. 23 explains this theory. Let P A be a great revolving circle upon
which Mars is fixed. (In the hands of the Alexandrian mathematicians
the spheres almost disappear, and they deal practically only with
circles.) If the earth were at its centre, as Eudoxus demanded,
Mars must always be at the same distance, but if we make the circle
eccentric to Earth, by putting its centre at C while Earth is at E,
then the distance and consequently the brightness will constantly vary,
and Mars will be brightest when at perigee P (point nearest Earth), and
faintest when in apogee A (point furthest from Earth).[49]

------------------------------------------------------------------------
[49] Greek _peri_ near, _apo_ away from, _ge_ Earth.
------------------------------------------------------------------------

[Illustration: Fig. 23. The Moveable Eccentric.]

But, as the Greeks had discovered, Mars attains his greatest brilliance
at different points of the zodiac, so P must be made moveable, and
it always happens when he is opposite the sun, therefore P must keep
pace with the sun’s apparent motion in the zodiac and P E always point
towards him. This was accomplished by making P C A turn round upon the
fixed point E, so that for instance when the sun had moved through a
quarter of his circle (in three months) P A had moved to P′ A′, and the
whole eccentric had moved into the new position shown in the diagram,
its centre C being now at C′. In other words, the centre of the
eccentric moves round Earth in the same time and in the same direction
as the sun, that is in one year, and “with the signs” (from west to
east).

At the same time, Mars is moving in an opposite direction on the
eccentric, and without entering into all the details of the problem,
we may add that the Greek geometers found that by determining the
proper relative sizes of the large and the small circle they could make
the two motions neutralize one another when the planet reached its
stationary points, and the retrograde motion prevail over the direct
when it retrograded. A similar arrangement was made for Jupiter and
Saturn.

In this very ingenious way the varying brightness as well as the
varying motions of these three planets were accounted for, without
violating the principle of uniform circular motion, and without
removing Earth from the centre of the Universe. She was also still
the centre of planetary motion, in a certain sense; but to place the
true centres of these planets’ spheres _outside Earth and in the
direction of the sun_ was a very suggestive step, and may well have
helped Aristarchus to his bold hypothesis. For he had only to put the
sun, not at some indefinite point along the line E A, but exactly at
the point C, and it became the centre of motion for Mars, Jupiter, and
Saturn, just as in the “Egyptian theory” it was the centre of motion
for Venus and Mercury. In this way he would arrive at the conception
of the sun circling round Earth and carrying all the planets with him,
(a theory which was held by the great astronomer Tycho Brahé in the
sixteenth century A.D.). Then a flash of insight may have revealed to
him the fact that this motion of the sun is apparent only, being but
the reflection of Earth’s own motion; for she is circling round the sun
like all the other planets.

It is, however, only a guess that the Moveable Eccentrics played this
part in the theory of Aristarchus. They did not long hold the field,
because they were not applicable to Venus and Mercury, which are never
seen in opposition to the sun. So they were thrown aside for another
system, the Epicycles, which illustrates much more simply the stations
and retrogressions of the planets, and can be used for them all.

Later on, when more irregularities of motion were discovered, it was
found necessary to combine eccentrics and epicycles, and by means of
this joint system it became possible at last to represent completely,
and as accurately as they could be observed, all the apparent movements
of the heavens. First, however, an immense amount of work had to be
done, and new methods devised, both in observation and mathematics.
The man who contributed most, in both ways, to make it possible, was
Hipparchus.


7. HIPPARCHUS.

[Sidenote: Hipparchus _c._ 140 B.C.]

Of this great man we know scarcely anything but what can be gathered
from the work he did, and this corroborates Ptolemy’s description of
him: “Hipparchus, lover of toil and truth φιλοπονον και φιλαληθεα.”
He lived about B.C. 140, since this is the date of the only book of
his still extant, and his work was not done in Alexandria, though he
may have studied there in his youth, and he used the Museum records.
We count him among the Alexandrians, as he belongs to this era, but
he seems to have been a private astronomer, who set up an observatory
of his own in Rhodes, his native place. Here we seem to see him,
surrounded by his primitive instruments and his papyrus books, patient,
eager, modest, seeking no fame and no reward but the joy of his work.
By day he would keep watch over the sliding shadow of his gnomon,
would write up his observations, make long calculations, and devise
new methods in mathematics, improve and modify his astrolabes and his
clepsydras; at night he would spend long hours with moon, planets, and
stars, making up for the defects and shortcomings of his instruments by
the skill and care with which he applied them to measure positions in
the sky. Nothing but the most loving and conscientious care could have
raised his work to such a pitch of accuracy, and made such rude means
suffice for such splendid achievements.

The book we possess, apparently an early one, is chiefly concerned with
the positions, the risings and the settings, of stars, and at the end
is a list of sixteen which came to the meridian at intervals of an
hour: from this list and the knowledge of spherical trigonometry which
he possessed, it would be possible to calculate the time at night to
within about a minute.

Hipparchus was able to construct a satisfactory theory of the sun
and to some extent of the moon, but he found more irregularities in
the planetary motions than Eudoxus had suspected. The records of his
predecessors were not accurate enough for him to construct a theory
for the planets, and he soon realized that one life-time would not be
long enough to collect all the data necessary, so, as Ptolemy tells us,
“Hipparchus, who loved truth above all things,” quietly set to work to
make as good and as many observations as possible, leaving it to his
successors to complete and explain them.

In the same spirit he undertook the laborious task, of which Pliny
speaks with awe as a presumptuous scheme, even for a god, “_rem etiam
Deo improbam_,” of numbering the stars. Pliny says he was led to do
this by the appearance of a New Star, which blazed out suddenly in
the constellation of Scorpio in b.c. 136, just as Nova Persei did in
Perseus in February 1901. He saw that even in the upper regions of the
eternal heavens, which Aristotle had supposed absolutely changeless,
changes may occur, and in order that even the least of these should
not pass unnoticed, he set to work to note the number, brightness,
and position of all he could see. This great catalogue of 1080 stars,
copied by Ptolemy in his _Almagest_, was the basis for all succeeding
catalogues, from Spain to Turkestan, until quite modern times. In it,
for the first time, the places of the stars were not merely described
according to their position in the constellation figures, but were
noted in degrees on the sphere, as is done to-day.

[Sidenote: Timocharis _c._ B.C. 280.]

One day, when comparing his notes with those of Timocharis, who had
worked at Alexandria about a century and a half earlier, he found that
the brilliant star Spica, the Ear-of-Corn which the Virgin carries
in her hand, had apparently moved nearer to the autumnal equinox by
about 2°. (Two degrees is about four times the angular diameter of the
sun). Of course he or Timocharis might have made a mistake, or Spica
might really be moving among the stars, or she might be carried along
with the rest by a slow movement of the whole star sphere. Apparently
Hipparchus satisfied himself that he could rely upon Timocharis’
observation, and took pains to verify his own; the second hypothesis
could be disproved by the fact that Spica does not change her place
perceptibly among her neighbours; and finally it became clear that her
motion is part of a slow apparent movement of the whole heavens.

[Illustration: Fig. 24. The movement of Spica.]

Here was a discovery of first importance, an unexpected reward of
patient accuracy, of which the white Spica, flashing down from summer
skies, may always remind us. Hipparchus had discovered the grand cycle
which we call the “Precession of the Equinoxes,” and before Spica
returns to the same position in which he saw her then, when she led
him to his great discovery, she will have been watched by generations
of astronomers for another twenty-four thousand years. No notice
of the cycle has been found as yet among the records of any other
nation, although it seems as if the astronomers of Babylon and Egypt,
and other countries where observations had been carried on for many
centuries, must have been aware of it. We can only imagine that at long
intervals of time they found that the stars had somehow changed, and
made corrections accordingly, but without understanding the nature of
the change. What Hipparchus thought about its cause we cannot tell:
probably he left all speculations to future astronomers, and confined
himself to noting the fact.

The displacement of Spica which he observed is shown in the diagram.

Both Timocharis and Hipparchus evidently measured her position
indirectly by comparing it with that of the moon, which was eclipsed at
the time,[50] and therefore known to be in the ecliptic and opposite
the sun. To find the sun’s distance from the equinox was an easy
matter, since his yearly course had long been carefully studied, and
the days on which he passed the equinoxes were regularly observed with
the gnomon. Spica, then, had moved eastward along an arc parallel to
the ecliptic, and since celestial latitude and longitude are referred
to the ecliptic, we may define her apparent movement in astronomical
language by saying that while her latitude had remained constant, her
longitude had increased by about two degrees; and further, as the
celestial equator is oblique to the ecliptic, this implied that her
declination (position north or south of the equator) had also varied.
The diagram shows that she had a less northerly declination than before.

------------------------------------------------------------------------
[50] _Syntaxis_, book VII.; Delambre, _Histoire de l’Astronomie
Ancienne_ Vol. II. page 247 (1817 edition).
------------------------------------------------------------------------

At this rate, Spica, which was now only 6° from the autumnal equinox,
would reach it in less than five hundred years, and thereafter would
lie east instead of west of it; and that she has in fact done so, may
be seen by consulting a modern star atlas. She is now 22½° of longitude
east of the autumnal equinox, and nearly 11° south of the equator. Her
south declination will continue to increase for about five thousand
years, after which she will come north again.

Ptolemy says that Hipparchus examined other stars, and found that they
also were increasing their longitude at what appeared to be the same
rate as Spica. The yearly amount of the movement, derived from the
Spica observations, is within a few seconds of arc of the true value,
which is 50¼ seconds; but Hipparchus would not fix any value until it
had been tested by further observation, and merely stated that it could
not be _less_ than one degree in a century _i.e._ 36 seconds per annum.

This is a very uncomfortable phenomenon for astronomers, since every
star is for ever changing its measured position on the celestial
sphere. Take three stars, one at the north pole, another on the
equator, and a third in the southern hemisphere. After some years,
the first will no longer be a pole star, the second no longer an
equatorial star, and the third may have so far increased its south
declination that it will be invisible at latitudes in our northern
hemisphere where formerly it used to rise above the horizon. One
compensation for this inconvenience is that if we know what star was
near the pole, or which stars lay along the equator, on any given
occasion, we can calculate the date. Thus it is believed that the Great
Pyramid was built when Alpha Draconis was the Pole Star, that is,
nearly 3000 years B.C.; and by a similar method Mr Maunder determines
the epoch at which the ancient southern constellations were invented,
as we have already seen.

The greatest inconvenience, and also the greatest historical interest,
attaches to stars like Spica which belong to constellations of the
zodiac, for if they are not stationary with regard to the equinoxes and
solstices they are not such simple guides to the length of the solar
year as the ancients supposed them to be. The scheme of the Babylonians
for beginning their month Nisan when the stars of Dilgan rose just
before the sun was an excellent one for a time, but if they had
continued it for many centuries they would have found that their year
was too long, and the months were all falling in the wrong seasons.
This has actually happened with Hindus and Parsis, who now keep their
New Year in the middle of our April, although when their calendar was
fixed, about thirteen hundred years ago, the years began at the spring
equinox. For the sun is like a runner in a circular race-course who
thinks he has completed a lap when he returns opposite a group of
spectators originally standing at the starting-point, but after several
laps he finds that the spectators and the goal no longer coincide;
either they, and also all the others surrounding the course are walking
away from it, or an unseen hand has been moving the flag towards him,
and so shortening the lap.

It is the flag which must count, in any case, not the spectators, and
with the sun it is the equinox which must count, and not the stars, for
this is the point at which he crosses the equator, making day and night
equal, and from this we count the beginning and ending of our seasons.
So our year is counted from equinox to equinox, and is twenty minutes
shorter than the “sidereal,” or star year, of the ancient Babylonians.
Hipparchus, from observations of equinoxes and solstices, made the year
365 days 5 hours and nearly 55 minutes, which is only 6 minutes longer
than the correct value.

[Illustration: Fig. 25. The Sun and the Equinox.]

After Hipparchus had made his discovery, astronomers agreed upon a
somewhat clumsy and very confusing device, by which the zodiac was
divided into twelve equal “signs” of 30 degrees, which bear the same
names as the zodiacal constellations, but whose beginning is always
reckoned from the vernal equinox. These twelve “signs of the zodiac,”
therefore, do not now agree with the twelve constellations of the
zodiac, and our present “first point of Aries,” which marks the vernal
equinox, is in the _constellation_ of Pisces.

What is the true cause of this strange phenomenon? Are the stars really
all in motion, or is it the equinox which moves?

The successors of Hipparchus, who believed that the stars were fixed
on a sphere, found no great difficulty in conceiving that this sphere
had a very slow easterly motion, round the poles of the ecliptic,
completing a revolution once in 36,000 years (_i.e._ one degree in
century). To us, however, it is impossible to believe that the stars,
which we have found to be at enormous and varied distances, are all
revolving at one rate, parallel to the ecliptic. The ecliptic, to us,
is simply the plane of Earth’s own orbit, and as she moves in it she
has a very slow “wobbling” motion on her axis, as well as the rapid
spinning of the diurnal motion, like the “wobble” of a spinning top.
The top has this motion because gravity is trying to pull it down from
its upright position; the earth because the sun is trying to drag her
slightly protuberant equator into the plane of her orbit.

The resulting motion is not a revolution of the earth, nor an apparent
revolution of the star sphere round Earth: what really happens may be
illustrated with the traditional orange and knitting needle.

Ignoring all motions but the one we are speaking of, let the points of
the knitting needle (Earth’s axis of rotation) trace out small circles
in space, and the equator of the orange will be seen to alter the
direction of its tilt, but without turning round (Fig. 26). Stick a pin
in the equator, and others in north or south latitudes, between equator
and pole; these will always remain facing you, but while the pole makes
its small circle, the equatorial pin will be seen to move up and down,
while the tropical and temperate pins trace out ellipses. These are the
movements which we see reflected in the stars; and if Earth’s diurnal
rotation were suddenly to cease, while her revolution in her orbit
and the movement of “precession” continued, we should see Spica, for
instance, sink slowly lower in the southern sky and after ages rise
again northwards, but there would be very little preceptible movement
east or west.

The movement observed by Hipparchus, then, was not a movement of Spica
and other stars, but a movement of the equinox. For the celestial
equator is simply a reflection of Earth’s equator in the skies, and as
it keeps changing the direction of its tilt in the way described, it
changes the point at which it cuts the ecliptic. This may best be seen
by taking two rings or hoops (two large curtain rings, for instance),
one of which just fits inside the other. Tilt the inner ring, so that
half of it is above and half below the other ring, and they touch
at two points, 1 and 2 (Fig. 27). The outer ring is the Ecliptic,
the inner the Equator, and where they touch each other are the
Equinoxes. Now move the inner ring, not sliding it round, nor making
any difference in the angle between the two, but simply so that they
touch at fresh points, 1′ and 2′. In this way you may make the points
of contact revolve entirely round. This is what the real equinoxes are
doing: while the equator opposite the group of stars in figure 25 rises
and falls, the equinox travels on, and finally returns to the same
place.

[Illustration: Fig. 26. The movement of Earth’s axis, which is the true
cause of Precession.

    _V_ is the vernal equinox, at the intersection
    of the equator and plane of the ecliptic: _APX_
    the earth’s axis, which always preserves the same
    inclination (23½%) to the plane of the ecliptic. As
    _APX_ slowly revolves round _T_ in the direction of
    the arrow, the vernal equinox is gradually shifted
    to _V_′, and so on.

(_From Young’s “Manual of Astronomy,” 1902._)]

The phenomenon is called “precession of the equinoxes,” because they
thus move on to meet the sun in his yearly course.

[Illustration: Fig. 27. Precession of the equinoxes.]

The discovery of precession is what has chiefly made Hipparchus famous,
but the invention of the astrolabe and of spherical trigonometry,
both believed to be due to him, his star catalogue, and his many
observations, more accurate than any made before, were so valuable as
pioneer work that Ptolemy justly called him the Father of Astronomy.
If Hipparchus could visit one of our observatories to-day, and see the
clock-driven equatorials, the transit instruments, the beautifully
divided circles read with microscopes, and the sidereal clocks, one
wonders whether he would be more astonished at the advance on his
astrolabes and clepsydras or at the homage paid to him as one in whose
footsteps all astronomers are proud to tread.


8. PTOLEMY.

    _Claudius Ptolemœus._ I know that I am mortal
    and ephemeral, but when I scan the multitudinous
    circling spirals of the stars, no longer do I touch
    Earth with my feet, but sit with Zeus himself, and
    take my fill of the ambrosial food of the gods.

For more than two centuries after Hipparchus very little original work
was done in astronomy, and no one seems to have had the courage to take
up his unfinished task and study seriously the difficult problem of
planetary motions.

[Sidenote: Posidonius _c._ 135 B.C. to _c._ 50 B.C.]

Posidonius the Stoic, who lived for some years in Rhodes, made a
fresh determination of the earth’s circumference, basing it not on
observations of the sun, like Eratosthenes, but of the star Canopus,
which in his time was just visible at Rhodes while in Alexandria it
rose “a quarter of a sign” (_i.e._ 7½ degrees) above the horizon. By
his method, the earth was a little smaller, (240,000 stadia instead
of 250,000), but it must have been difficult to measure the distance
between Rhodes and Alexandria over the sea, and it is impossible to
say when a star is exactly on the horizon. Posidonius also observed
the tides in the Mediterranean, and showed that “Ocean follows the
movements of the heavens,” and especially of the moon, having daily and
monthly periods.

[Sidenote: Geminus _c._ 70 B.C.]

A little later Geminus wrote an Introduction to Astronomy, which was an
excellent little book as far as it went, but although he was apparently
a native of Rhodes, and speaks of Hipparchus, he seems to know nothing
of his work, for he does not quote his careful determination of the
length of the year, nor his discovery of precession.

[Sidenote: Cleomedes _c._ 20 B.C.]

[Sidenote: Theon of Smyrna _c._ 100 A.D.]

Nor were other writers, such as Cleomedes and Theon of Smyrna, better
informed, and they added nothing new to the advance of astronomical
science.

[Sidenote: Ptolemy _c._ 140 A.D.]

But at last a worthy successor arose at Alexandria, the immortal
Ptolemy, whom Dante met in that Limbo of antique spirits which was
almost Elysium, although on the brink of the Inferno.

We do not know when Ptolemy was born nor when he died, nor where was
his native town: we only know that his first recorded observation was
made in the eleventh year of the Emperor Hadrian, that is A.D. 127, and
his latest in A.D. 150, and that he lived and studied in Alexandria. He
had splendid opportunities for carrying on the work of Hipparchus, for
besides the use of the instruments in the Museum Observatory, he had at
hand all the Museum records, which included the writings of Hipparchus.
Ptolemy was not so painstaking and accurate an observer as Hipparchus,
but he was a very able mathematician to whom it was evidently a joy
to handle figures and work out problems. By examining a number of
observations spread over several centuries, and combining them with his
own, he was able to accomplish the task in which so many others had
failed, and to frame a system which embraced all the celestial motions
then observed. The monumental summary in which he set forth this system
contains a great deal of interesting information about his methods
and instruments, and about the work of Hipparchus, for whom he always
expresses the most generous admiration. The original name of his book
was the “Mathematical System of Astronomy,” but his admirers having
called it the “Great System,” _Megiste Syntaxis_, the Arabs affixed
their article _al_ and gave it the name it preserves to this day, of
_Almagest_. It remained the standard treatise on astronomy until the
_De Revolutionibus Orbium Celestium_ of Copernicus appeared in 1543.

The name of his book indicates the scope of Ptolemy’s work. It was to
represent all the observed motions of the heavenly bodies by means of a
mathematical system, so that they became amenable to calculation; but
to explain the causes of these motions was thought to lie quite outside
an astronomer’s province. It was not for a mere observer and calculator
to determine which motions were real and which apparent, else Ptolemy
must have decided in favour of Earth’s rotation, for he says that
it would be much easier to account for celestial motions on this
assumption. Nor was it his business to investigate the substance of the
stars. Little did he dream that astronomers would one day solve such
problems, and uphold their conclusions in the face of all the world:
for him, as for his contemporaries, the decisions of the philosophers,
and especially of Aristotle, were final, and his task was to describe
what he saw in the light of their teaching.

He brings forward, in the introduction to his book, a few arguments
against the absurd notion, taught by some, that Earth is in motion,
turning on her axis or moving through space; but all that he proves
is the immense difficulty, even to a trained mind, of accepting these
theories, and the great authority of the philosophers who denied
them on abstract principles. Educated Greeks might still discuss the
nature of the heavenly bodies, as in Plutarch’s delightful dialogue
_On the Face of the Moon_, (written about half a century before the
days of Ptolemy), and might ridicule the law of gravity, laughing at
the absurdity of supposing that if the middle of a man’s body were at
the middle of the earth, his feet as well as his head would be “up,”
and that falling weights if they reached this point would stop short,
or oscillate to and fro. Yet even they all agreed that the fixed
stars do most probably move “in a circle of eternal and never-ending
revolution,” and that they are of a pure and eternal substance unlike
Earth; and for the professional astronomers of Alexandria these axioms
were assumed as the basis of all their work. Earth must be immoveable
at the centre of the Universe because the heavy stuff of which she is
made sinks necessarily to the centre and there remains in globular
form without need of support; the heavenly bodies must be in motion,
because, being of ethereal substance, it is their nature to revolve
eternally in circles.

This being granted, we can feel nothing but admiration for the extent
of Ptolemy’s knowledge, the comprehensiveness of his scheme, and the
skill and patience with which he overcame its difficulties.

Earth, according to Ptolemy, is but a point compared with the immense
surrounding sphere in which the stars are set, and this turns always
round us, communicating its motion (he does not inquire how) to sun,
moon and planets, so that day follows night, and the heavenly bodies
daily rise and set. For the slow movement of precession, which also
affects all heavenly bodies, Ptolemy accepted the least value of
Hipparchus, one degree in a century, only testing it in rather a
perfunctory way, which was a great pity, for he might have determined
it much more closely after an interval of some 250 years. But one man
cannot do everything, and he doubtless thought it best to spend more
time on the planets, whose intricacies had baffled Hipparchus and gave
him also a great deal of trouble.

He retained the great spheres which were supposed to carry them round
Earth, inside the star sphere, but the chief feature of his system is
the use of small spheres, which were fixed on the larger, and therefore
called “epicycles,” while the large were known as “deferents” or
carriers. The general principle of epicycles is very simple, as may be
seen by comparing the two diagrams.

Fig. 28 shows the path of Mars as we saw it among the stars of Pisces
in the year 1909. Throughout July the planet was travelling in its
usual direction, “with the signs,” but on August 22nd it came to a
stop, then turned and travelled backwards “against the signs” until
October 26th, when it stopped again, reversed its direction once more,
and during the rest of the year moved rapidly forward.

Fig. 29 shows the principle on which Ptolemy would have explained this
curious track. Each planet was supposed to be fixed on a small circle,
the epicycle, and this was fixed upon a large circle, or deferent, upon
which it travels in the direction shown by the arrow, at a uniform
speed, returning to the same place in the sidereal period of the
planet. Thus Mars, as seen from Earth, which is near C the centre of
the deferent, makes a great circle through all the zodiac in two years,
Jupiter in twelve, and so on. But meanwhile the epicycle is rotating
round its own centre, C1, and when the planet reaches the point
marked S, the two motions neutralize one another, so that it appears
stationary, as Mars did on August 22, 1909. After this, the motion of
the epicycle more than counter-balances the motion of the deferent, and
the planet seems to reverse its direction until it reaches the point on
the epicycle marked S′. After this the two motions are once more in the
same direction, so the planet is seen to move rapidly forward, as Mars
did after October 26.

[Illustration: Fig. 28. The Path of Mars among the Stars, 1909.]

[Illustration: Fig. 29. The Epicycle.

Ptolemy’s method of accounting for movements such as those shown in
Fig. 28.]

[Illustration: Fig. 30. Planet retrograding, and in opposition (_i.e._
in opposition to the sun.)]

In this extremely ingenious way the strange planetary oscillations were
accounted for, without violating the law of uniform circular motion,
and in a more convenient and satisfactory way than by the concentric
spheres of Eudoxus or the moveable eccentrics of Apollonius. Each of
the five planets was provided with an epicycle and a deferent, and
these were made of the proper relative size and given the right speed,
so that the motions should correspond with what we see in the sky.

Ptolemy calls the oscillation a planet’s “anomaly with regard to the
sun,” because (as we have seen when discussing the moveable eccentrics)
it was known to be connected in every case with a planet’s angular
distance from the Sun. On September 24, when Mars was in the middle
of his retrograde arc in Pisces, the sun was exactly opposite, in
the constellation of Virgo. This is found to be always the case, not
only with Mars, but with Saturn and Jupiter too. Whenever one of
these planets has the position O on its epicycle, and therefore is
retrograding, the sun will be found to be exactly opposite in the
sky. Mars comes into this position, and is opposite the sun, once in
780 days; this, therefore, Ptolemy called the period of his epicycle,
while a little less than two years was the period of the deferent. The
two periods of Saturn are 378 days and 29½ years nearly; of Jupiter 399
days and nearly 12 years.

[Illustration: Fig. 31. Venus, Mercury, and the sun.]

Venus and Mercury betray their dependence upon the sun in more striking
fashion, for since these planets simply oscillated from one side to the
other of the sun, their epicycles must be supposed to be keeping pace
with him all the way round the zodiac. Fig. 31 shows their relation
to one another. On September 25, 1911, Mercury was seen from Earth as
a morning star as far west of the sun as it is possible for him to
travel, while Venus, after shining as an evening star all the summer,
had come into line with the sun and become invisible.[51] On December
7 following, the rotation of the epicycles (Ptolemy would say) had
brought both planets to new positions, Mercury now being an evening
star at his “greatest elongation east,” and Venus a morning star. But
the centres of the two epicycles always remain in a line with one
another and the sun, and so their periods on the deferents are the same
as his, viz. one year. The epicyclic periods, or intervals between two
“greatest elongations” west or east, are 116 days for Mercury, 584 days
for Venus.

------------------------------------------------------------------------
[51] Venus had passed her “inferior conjunction with the sun” on Sept.
15.
------------------------------------------------------------------------

We still explain the complicated course of the planets by resolving
it into two approximately circular motions, but we know now that only
one belongs to the planet itself, the other is Earth’s own motion. The
reason why the sun’s position affects the position of every planet
is simply that the epicycles of Mars, Jupiter, and Saturn, and the
deferents of Venus and Mercury are reflections of Earth’s yearly
journey round the sun.

Ptolemy had by no means finished with the planets when he had provided
each one with an epicycle to represent the “anomaly with regard
to the sun.” Hipparchus had noticed that there was another lesser
irregularity, which seemed to be periodical likewise, although no
former system had taken it into account; and this he called the
“anomaly with regard to the zodiac,” because the speed of each planet
and the amplitude of its loop varies slightly according to the part of
the zodiac it happens to be in. He suggested that this might be dealt
with by combining the two theories of epicycles and eccentrics, and
this suggestion Ptolemy adopted with success. He placed each deferent
with its centre not exactly at the earth, but at a certain small
distance which was different for each planet. (This is not shown on our
small-scale diagrams, therefore Earth appears at the exact centre.)
The true explanation of this irregularity is that each planet’s path
is not strictly circular, but elliptical.

Besides this, Ptolemy had to represent the planet’s movements north and
south (note how this varies in fig. 28.). This was partly managed by
the aid of small wheels, rotating in such a way that they lifted and
lowered the epicycle as required.

Although Ptolemy quotes Babylonian observations of lunar eclipses
dating back as far as the eighth century B.C., the oldest planetary
observations that he uses were made only four hundred years before his
time, and they were probably Greek. Even these were generally very
rough. For instance:—

    In the 496th year of Nabonassar, on the 17th day
    of Choeac, in the morning, Mercury was three
    moon-breadths north of the tail of Capricorn.

    In the same year, Phamenoth the 30th, Mercury was
    three moon-breadths south of the horn of Taurus
    which is also the foot of the Charioteer.

The first year of Nabonassar (a Babylonian epoch) corresponds with
B.C. 747, so the 496th year is B.C. 251. The months used by Ptolemy
are usually Egyptian. The later observations, made with an astrolabe,
were much more precise; Ptolemy quotes one from Theon of Smyrna, which
states that Mercury was 3° 50′ in advance of the Heart of the Lion
(Regulus), and for his own observations he also usually gives the sign,
degree, and minute. Sometimes the planets had been observed so near
stars that their positions could be very accurately determined by the
aid of Hipparchus’ star catalogue. Timocharis, on a certain morning in
the 13th year of Ptolemy Philadelphus (B.C. 273), saw Venus beside the
last star in the wing of the Virgin (Beta Virginis); Ptolemy himself
saw her so close behind a certain star in Aquarius that she seemed
to touch it with her rays; and in the 83rd year after the death of
Alexander, Jupiter had been observed to eclipse the Southern Ass, that
is the southernmost of the pair of stars on either side of the little
cluster in Cancer which the ancients called the Manger.

[Illustration: Fig. 32. The sun’s Deferent. (Its eccentricity is
exaggerated).]

The sun was much easier to manage than the planets. Moving always
in the same direction, he needed no epicycle, and remaining always
in the ecliptic, no wheels. His one irregularity, the varying speed
in different parts of the zodiac, which Meton had discovered and
Calippus confirmed, Hipparchus accounted for by placing him on
eccentric deferent; Ptolemy adopted this without change, and made the
year the same length as Hipparchus had done. As the slowest motion
was observed when the sun was in the sign of Gemini (at the time of
year corresponding with the end of our month of May), the eccentric
was placed as in the diagram; and the sun, supposed to be revolving
uniformly round the centre C, had a slower motion as seen from Earth
when he went north, because he was then more distant.

We know now that it is really Earth which revolves round the sun, but
the elliptical shape of her orbit is not unlike the eccentric deferent
which the Greeks gave to the sun, and they guessed quite rightly from
his motion that he is further from us in one part of the year than
in the other. This is easily proved to-day by the fact that he grows
apparently smaller, as shown by photographs or measurements taken at
different times of year, but the change was not perceptible to the
rougher methods of the ancients.

It was a pity that Ptolemy did not take more pains to verify the work
of Hipparchus on the sun, for the sun’s “apogee,” or point of greatest
distance from Earth, has an extremely slow motion among the stars which
ought to have been quite perceptible in nearly three centuries;[52] but
here again he seems to have thought that where Hipparchus had given so
much attention he might pass on to something else, and so missed an
interesting discovery.

------------------------------------------------------------------------
[52] It amounts to 5 degrees of longitude in 300 years.
------------------------------------------------------------------------

[Illustration: 1911, July 1. 1912, Jan. 3.

Fig. 33. Apparent Variation in the Size of the Sun. [_To face p 146_

Two half photographs of the Sun, taken at Kodaikanal Observatory. The
smaller was taken two days before apogee, the larger on the day of
perigee.]

Instead, he worked very hard at the moon, and added another periodical
irregularity to those already known. Perhaps his feelings were somewhat
mixed when this happened, his pride and pleasure in his important
discovery being counter-balanced by the consciousness that it would
still further complicate his lunar theory. Our satellite is acted
upon by ourselves as well as by the sun, so that she suffers many
perturbations, for Earth, though so small compared with the sun, is
comparatively near. Ptolemy’s discovery was a difference in her speed
at full and new, as compared with her intermediate phases, and this
periodic difference is called by modern astronomers the “evection.” It
was already known that her nodes, or the points at which she crosses
the ecliptic, are in constant retrogressive motion, just like the
equinoctial points, where the sun crosses the equator; but the moon’s
crossing points, instead of taking thousands of years to circle the
zodiac, run round in about eighteen years. This was discovered early,
because observations were chiefly made during eclipses, and at these
times the moon is always at a node, that is to say, she is crossing the
ecliptic, the sun’s path; otherwise the eclipse could not happen. It
was also known that she has a varying speed in the zodiac, and that her
apogee, where the motion is slowest, instead of being apparently fixed,
like that of the sun, also runs round the zodiac, but with a direct
motion, and in a period of about nine years.

We need not enter into all the details of Ptolemy’s arrangements for
the moon, which are exceedingly complicated, but it is interesting to
note that he does not explain her varying velocity by an eccentric, as
with the sun and the planets. She has an eccentric, but Ptolemy needed
it for representing his own discovery, the evection, so he gave her an
epicycle, using it in quite a different way from the epicycles of the
planets. This epicycle also revolved while moving on the eccentric, but
in the opposite direction, and there was so little difference in speed
between the two motions that it never brought the moon to a stop, nor
reversed her direction, but simply increased and retarded her motion
alternately during her monthly revolution. Thus, when the moon was at
M, in what Ptolemy called the upper apsis (or arc) of her epicycle, or
as we should say in her apogee, the motion on the epicycle was contrary
to her motion on the eccentric, and made it seem slower. When the
epicycle had travelled halfway round the eccentric, it had also made
nearly half a revolution on its own axis: consequently the moon was at
M¹, near the lower apsis, or perigee, and the motion on the eccentric
seemed to be accelerated.

[Illustration: Fig. 34. The moon’s epicycle and deferent.]

The slight difference in speed between the two motions accounted for
the continuous displacement of the apogee in the zodiac, as may be seen
from the diagram. For suppose that when in apogee at M the moon is seen
from Earth among the stars in the middle of Taurus. At the return of
the epicycle to this place next month, she has not yet quite completed
a revolution on her epicycle but is at M², and will not be in apogee
until the centre of her epicycle is advanced 3° further in Taurus.
After some time (five months), apogee does not occur until the moon is
in Gemini, and it will be nine years before it occurs again in Taurus.

These are the leading features of the system by which Ptolemy
represented the motions of the planets, the sun, and the moon. He is
uncomfortably conscious that it may strike us as very complicated, and
in his last book he makes a kind of apology. We must remember, he says,
that we are not dealing with earthly machines which jar and wear, but
with celestial bodies which have no weight, cause no friction, and are
eternally the same. Delambre somewhat cruelly retorts that he need not
have wasted time in writing such rubbish, but have been content to put
his results into tables.

But what true astronomer could be content with tables and nothing
more? He must try to understand their significance. Nearing the end of
his great work, which had cost so much labour, and was so brilliant
a success within its limits, Ptolemy allows us to see in this little
paragraph that he felt he had but touched the hem of Nature’s veil,
and longed in vain to lift it. The circles which he manipulated so
skilfully were only mathematical abstractions to him:[53] what was
the reality behind? What were the stars? whence came their unwearied
strength, their eternal calm? The power of Egypt, of Assyria, and of
Persia had declined, Greece was now laid low, and it was the day of
Rome, but still Venus pursued her ancient path among the little stars
of Aquarius, and when all faded in the solemn dawn, the sun arose in
his ancient majesty. Then Ptolemy looked at his circles and triangles,
and felt how inadequate they were; yet it was the nearest approach he
could make to truth.

------------------------------------------------------------------------
[53] This is evident from the way he treats them, picking up an
epicycle or a deferent just as best suits the purpose in hand and
explaining sometimes that either would answer equally well.
------------------------------------------------------------------------

They did indeed represent very beautifully the celestial motions, and
also in a general way the variations in brightness or diameter, but
their unreality is betrayed by the fact that the latter was often
grossly exaggerated, as for instance with the moon, whose epicycle had
to be so large, in order to represent her motions, that at perigee
she ought to appear twice as large in diameter as at apogee! Ptolemy
can hardly have failed to notice this, though he does not mention it.
With regard to the planets, he is careful to tell us that he knows no
way of finding their real distances: the ratios of their epicycles
to their deferents he had carefully computed in each case, but to
estimate the diameters in stadia was utterly beyond his powers. He
believed, however, that all were very much nearer than the stars, and
more distant than the moon, and he found universal agreement among
astronomers in placing Saturn, Jupiter, and Mars, beyond the sun, in
order of the periods of their deferents, which were all longer than
a year. Venus and Mercury, however, had periods the same as the sun:
on which side of him, then, must they be placed? Some modern authors,
Ptolemy says, thought they were beyond the sun, but he agrees with
the most ancient, and places them between sun and moon. The general
disposition of the heavenly bodies according to Ptolemy is shown
in Fig. 35, with the periods of epicycles and deferents, and the
directions of the several movements, but epicycles and spaces between
deferents are all made equal. It will be noted that the sun has no
epicycle and that the moon turns on hers in a reverse direction, that
the centres of those of Mercury and Venus are in a line with the sun,
while the lines joining Mars, Jupiter, and Saturn to the centres of
theirs are in each case parallel with the line joining Earth and Sun.
Beyond all the wandering stars is the sphere of the fixed stars, moving
in its vast period of 36,000 years; and the whole system is carried
round Earth in one great revolution of a day and a night.

[Illustration: Fig. 35. The Ptolemaic system.

The arcs of circles are portions of the deferents which carry round the
smaller circles (the epicycles) in the periods named at the side.]

And here we have to note one astonishing fact. Although the planets
were all beyond reach of measurement, it was not so with the moon,
which the Greeks rightly recognized as our nearest neighbour. They had
actually achieved the long-desired feat of measuring her real size and
distance.

The fundamental principle on which they worked is easily explained. If
we look out of a window at a tree in the garden, it appears against
a background of some distant scenery; if we alter our position by
walking to another window, the tree changes its place with regard to
the relatively motionless background, and its apparent change of place
bears a definite proportion to its distance from us. A tree near the
house changes its position greatly, a tree at the far end of the garden
much less. From careful measurements of the angle through which the
tree appears to have moved and the distance we have walked between the
two windows, the distance of the tree from the house may be easily
deduced.

The tree in the garden is the moon, the distant landscape is the
star-spangled sky. The space between the two windows must be increased
to thousands of miles, but the astronomer need not walk it. If he makes
his first observation when the moon has just risen, carefully measuring
her position among the stars, the revolving Earth will carry him to
a new position in a few hours, when with the moon high in the sky he
can once more compare her position with the same stars, and from the
change he then finds he can deduce her distance. The Greeks thought
it was the sky, and not the earth which moved, but this makes no
difference, as the question is one of relative motion only.

The problem, however, when applied to the moon, is a complicated one,
implying not only skill in trigonometry and the possession of suitable
instruments for measuring the necessary angles, but also accurate
knowledge of the size of the earth and the motions of the moon, since
her progress eastward among the stars during the interval between the
two observations must be allowed for. Hipparchus and the astronomers
of Alexandria were the first to qualify themselves for attacking this
difficult problem, and the proof of their success is that Ptolemy’s
value for the distance of the moon is very near the truth as obtained
by modern methods. The same method is now used, only it is found
better to do what was not possible for the Greeks, namely to compare
observations made at places several thousands of miles distant, for
instance Greenwich and the Cape, instead of allowing the same place to
be moved by the earth’s rotation.

When the distance of the moon had been thus discovered, it was a very
simple matter to find her real size from her apparent size.

The distances of all other heavenly bodies are too great to be
determined by naked eye methods, for the displacement (technically
called “parallax”) is so small that it is quite invisible without a
telescope. Hipparchus had tried repeatedly to measure the distance of
the sun, but recognized that neither the method of Aristarchus nor any
other was really conclusive. It was, however, the best attempt that had
been made, and Ptolemy assumed that he knew the distance to be about
twenty times that of the moon, so he gave the sizes and distances of
these two bodies as follows, taking Earth’s semi-diameter as unit:—

              According to Ptolemy.            Modern Values.
          _Semi-diameter.   Distance.   Semi-diameter.   Distance._
    Moon   ⁵/₁₇ (=0·290)      59               0·273       60·3
    Sun     5½               1210              109·4      23,439

In Books VII and VIII of the _Almagest_ Ptolemy describes the
48 ancient constellations and the course of the Milky Way among
them. The position of each star is noted as it appears in its
constellation-figure, but the celestial latitude and longitude is also
given, and this great catalogue is evidently taken from Hipparchus.

        PTOLEMY’S FORTY-EIGHT CONSTELLATIONS.[54]

------------------------------------------------------------------------
    [54] Taken from the _Almagest_ catalogue, as given in Delambre’s
    History.
------------------------------------------------------------------------

        Ursa Minor                Pegasus
        Ursa Major                Andromeda
        Draco                     Triangulum
        Cepheus                   Cetus
        Auriga                    Orion
        Corona Borealis           The River (Eridanus)
        The Kneeler (Hercules)    Lepus
        Lyra                      The Dog (Canis Major)
        The Bird (Cygnus)         Canis Minor (Procyon)
        Cassiopeia                Argo
        Perseus                   Hydra
        Böotes                    Crater
        Ophiuchus                 Corvus
        Serpens                   Centaur
        Sagitta                   The Wild Beast (Lupus)
        Aquila                    Ara
        Delphinus                 Corona Australis
        Equuleus                  Piscis Australis,
        Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio,
        Sagittarius, Capricornus, Aquarius, Pisces.

Ptolemy sometimes remarks on the colour of the brighter stars, and
always mentions the brightness, or “magnitude” as we call it now, for
the classification of Ptolemy (or Hipparchus?) was found convenient
and accurate enough to be retained by modern astronomers, and the same
system is now continued with the faint telescopic stars.

The stars ranked as “first-magnitude,” or brightest of all, are fifteen
in number, and as these are evidently the “quindici stelle”[55] alluded
to by Dante in _Par._ xiii. 4, it will be interesting to give a list of
them here.

------------------------------------------------------------------------
[55] Fifteen stars.
------------------------------------------------------------------------

                   PTOLEMY’S FIRST-MAGNITUDE STARS.

      _Name and Description            Modern Name and Meaning._
        _in the Catalogue._
     1. Arctouros, fire-coloured       Arcturus (the Bear-Watcher).
     2. The brightest star in the      Vega, in Lyra. (Falling Eagle,
          Lyre                           Arabic).
     3. Aichs (the Goat)               Capella (Little Goat, Latin).
     4. The brightest star of the      Aldebaran. (The follower,
          Hyades, fire-coloured          because following the
                                         Pleiades, Arabic).
     5. Basiliskos (the royal), on     Regulus (Latin equivalent).
          the heart (of Leo).
     6. The tip of the tail (of Leo )  Denebola (Lion’s Tail, Arabic).
     7. Stachys (Ear-of-Corn)          Spica (Latin equivalent).
     8. The last of the Water and      Fomalhaut. (Mouth of the
          Mouth of the Southern          Fish, Arabic).
          Fish.
     9. The fire-coloured bright       Betelgueux. (Shoulder of
          star on the shoulder           Giant, Arabic).
          of Orion.
    10. On the left foot of Orion,     Rigel. (Foot of the Giant,
          common to the Water.           Arabic).
    11. The last of the River          Achernar (Arabic equivalent).
    12. The very brilliant star,       Sirius (Greek _Seirios_, or
          fire-coloured, at the          _Sothis_, from the Egyptian
          mouth of the Dog,              _Sept_),in Canis Major.[56]
          called the Dog.
    13. Prokuon (the preceding         Procyon (in Canis Minor), which
          Dog), on the thigh of          rises before Canis Major.
          Prokuon
    14. Canopos, on the rudder         Canopus (an Egyptian god, and
          (of Argo)                      a town on the Nile delta).
    15. The tip of the right forefoot  Alpha Centauri.
          (of the Centaur).

    Altair and Antares were counted as second magnitude,
    though we now class them among the first.

------------------------------------------------------------------------
[56] Lockyer, _Dawn of Astronomy_, p. 196.
------------------------------------------------------------------------

It will be seen from the above that only two of these fifteen
brightest stars of Ptolemy’s still bear their Greek names, Arcturus,
and Procyon; but most of the other modern names are direct translations,
either into Latin or Arabic, of Ptolemy’s description or name for the
star, while Vega and Aldebaran have preserved their original Arabic
names (much corrupted), and Canopus and Sirius are derived from the
Egyptian. Regulus-Basiliskos apparently comes from Babylon, for the
name of this star on tablets of the second century B.C. was Shar-ru,
which means “royal.”

Ptolemy’s “Last of the River” was taken by his Arab and other
commentators to be the first-magnitude star which consequently they
named Achernar, but this was too far south to be visible at Alexandria,
though possibly he heard of it or saw it himself at Syene, where it
rose over the horizon in his times. Delambre thinks it is the same as
Fomalhaut, which already belongs to two other constellations in the
star catalogue; Brown suggests it was Theta Eridani, which may have
been brighter sixteen centuries ago. Perhaps it was the star we now
call Alpha in the Phoenix, for this lies between the last bend of the
River and the Water of Aquarius, and its magnitude is between first and
second. The stars of the Southern Cross are included by Ptolemy in the
stars about the hind feet of the Centaur, though it is difficult to
identify each one with certainty: the positions are not very accurately
given.

Ptolemy wrote also on Astrology, or as it was then called Judicial
Astronomy, and his work on the subject, which is in four books,
received the name of the _Tetrabiblios_. It seems that astrology was
not very much believed in by the Greeks, for he protests that the
influences of the stars are real, and can be known and predicted, but
allows that this part of astronomy is much more difficult than the
mathematical part, with which he had dealt in the _Syntax_, and that
it has not yet been perfected, and therefore it is sometimes slandered
as untrue. Astrologers sometimes make mistakes, like doctors, yet both
astrology and medicine are useful arts. He mentions especially the
Egyptians as practising it.

Only second in importance to the _Almagest_, and even better known in
old days, was Ptolemy’s work on Geography. In this he shows how the
size of the earth and the latitudes and longitudes of places on Earth,
can be discovered by observations of the heavens. For Earth’s diameter
he adopts the value found by Poseidonius. His terrestrial globe had a
moveable half-circle attached to the poles, which was divided into 90°
from the equator in both directions, so that by placing this against
any spot on the globe, its latitude north or south of the equator
could be immediately read off. Only half the equator was marked on
this globe, and divided into 180°, for the known part of the earth
all lay within these limits. The parallels of latitude marked were
not the same as we use, though the most northerly fell very close to
the Arctic Circle: it showed the latitude of the Island of Thule, far
away “towards the Bears,” as Ptolemy expresses it, meaning that it lay
under the constellations near the North Pole. The most southerly was
not far below the equator, and others were marked between these which
divided the known Earth into “climates,” according to the height of the
Pole and the length of the longest day in each. Among the many towns
which figured on this globe we may mention Alexandria, Rome, Athens,
Jerusalem, Florence, Cadiz, Paris, Strasburg, London, Bath. Meridians
were marked at every 5 degrees. From this globe Ptolemy shows how a
plane map may be constructed. He took Rhodes as the central meridian,
because it had a nearly central position among the “climates,” and was
the place in which Hipparchus had observed.

Ptolemy also wrote books on Optics, on the theory and construction of
Dials, and on Music!




V. RETROSPECT.


The _Almagest_ is the last word of Greek astronomy. We have seen how
from the dawn of Greek history, as far as we can trace it back in
literature, the Greeks were familiar with the skies, and how the most
ancient of their philosophers had tried, chiefly by abstract reasoning,
to discover the cause of the circling motions—never changing, never
ceasing—of sun and stars. When the seemingly unruly movements of the
planets were known, they still felt sure that there must be some
underlying principle which would bring all into harmony. Inspired by
Plato, and helped by the Egyptians, Eudoxus took the first step towards
finding this principle by careful study of the planetary motions,
and at last, after many generations of observers and mathematicians,
Ptolemy was able to describe these motions as accurately as was
possible with the methods available.

At first the heavenly bodies had been thought of as gods, then as
worlds like our own, then as spheres of ethereal fire. They were
swept round by a mighty wind, they ran on wheels, they floated in the
ether, they were set in crystal spheres; the controlling force was
the principle of number or harmony, an all-pervading World-Soul, a
host of immaterial intellectual Beings subject to one eternal First
Mover. It was also suggested that the greater part of the motions were
apparent only, that Earth was really in motion, spinning on her axis,
revolving round a Central Fire, or revolving round the Sun. But these
ideas had not enough evidence to support them when suggested. Had a
great imaginative thinker, a Pythagoras or an Aristarchus, arisen
after Ptolemy, he could have shown in detail how by assuming these
two motions the phenomena could be more simply accounted for, and he
could have made out a very good case for their probability.[57] But the
time was past then for such bold originality, and the explanation of
Aristotle was universally adopted. He, as we saw, placed the abode of
the gods, the rulers of the universe, beyond the outermost sphere, and
found the principle for which all were seeking, which should be the key
to all celestial motions, in the law of circular motion.

------------------------------------------------------------------------
[57] The changing latitudes of the planets, for instance, which gave
Ptolemy much trouble, are much more easily explained when it is granted
that they partly depend upon Earth’s motion in an orbit whose plane is
slightly inclined to the planes of their orbits.
------------------------------------------------------------------------

The Greeks had at first thought that the earth was a disc, under a
tent-like sky; then it was a cylinder, with the sky in tiers above;
then a huge hemisphere filling half the universe. But they discovered
that it was a sphere, surrounded on every side by the heavens; and they
found its true size, and that the portion of it which was known to
them was less than a quarter of its whole extent. They explained the
marvel of Earth’s remaining unsupported in space by the known facts of
gravity, arguing that the falling of every particle of earth towards
Earth’s centre proved that it was also the centre of the Universe, and
that every heavy thing tended thither by a law of nature.

They also knew the size and the distance of the moon; they realized
that the planets were all immeasurably remote, and the stars vastly
more distant still. They believed that there were great intervals
between the planets, corresponding to the differences in their periods
of revolution, but the stars were always thought of as set in a great
sphere, and therefore all at the same distance from Earth at its
centre. The relative positions of the stars on this great sphere,
and times of rising and setting of many of them had been known in
a rough way for many ages, through the familiar appearance of the
constellations, named we know not by whom; but Hipparchus measured
their positions in degrees, and was able to foretell where any star
would be in the sky for any place or time. He also discovered the
Precession of the Equinoxes, and this was thought to prove a slow
rotation of the star sphere.

Astrology was learned by the Greeks in Egypt and the East, but was
never practised with the enthusiasm shown by their teachers.

As regards the division of time, the Greeks adopted from the
Babylonians the twenty-four hour day which we still use, and their
months began with the young moon. Their year therefore had to contain
a whole number of months, and it had sometimes twelve, and sometimes
thirteen, as with the ancient Babylonians, but the system by which
this was arranged was quite different, as they did not depend upon
observations of the stars, but counted the number of days between
equinox and equinox by means of gnomons. Great difficulties were
found in trying to reconcile the lunar and solar periods. The ancient
12-month year, used in the time of Hesiod, was found to be much too
short, and alternate years of 12 and 13 months made the period too
long; then an eight-year cycle was invented, but this had to be
constantly corrected, which led to great confusion. As we have seen how
carefully Meton and Euctemon had determined the length of the tropical
year, even before the days of Eudoxus, surprise may be felt that a
calendar year was not fixed to correspond accurately with the movements
of the sun, ignoring the irreconcileable movements of the moon, but it
is difficult for us to realize in these days how wrong and strange it
seemed if a new moon occurred in the middle or at the end of a month,
instead of at the beginning. In Aristophanes’ play of _The Clouds_,
which was acted in B.C. 423, the moon was said to grumble because men
would not keep the months as she showed them:—

            “Yet you will not mark your days
    As she bids you, but confuse them, jumbling them all sorts of ways,
    And she says the gods in chorus shower reproaches on her head,
    When in bitter disappointment they go supperless to bed,
    Not obtaining festal banquets duly on the festal day.”

Then Meton made his celebrated discovery that nineteen tropical years
correspond almost exactly with 235 synodic months (the difference is
in fact only a few hours), and a cycle of 19 years was arranged, which
was adopted by all Greek states and dependencies. Some of the years had
twelve and some thirteen months, and some of the months 29 and others
30 days, but all followed in a regular order, and when one cycle was
completed another was begun. The total number of days in each cycle
was 6940, and as this is only 9½ hours longer than 19 true tropical
years, it follows that the average year in the Metonic cycle was only
half an hour longer than it should have been.[58] The average month was
not quite two minutes longer than the true synodic month.

------------------------------------------------------------------------
[58] It therefore really approached more nearly the sidereal year,
although the cycle was based on the tropical year.
------------------------------------------------------------------------

An improvement even on Meton’s cycle was made by Calippus, who
proposed to correct its too great length by quadrupling the period,
and then deducting one day from the whole. This would have given a
cycle of 76 calendar years, in which the average year was 365¼ days, or
only 11¼ minutes too long. It does not seem, however, to have been ever
brought into actual use as a calendar, but Ptolemy often refers to the
Calippic epoch as a date from which to calculate celestial phenomena.

[Sidenote: Theon of Alexandria _c._ 380 A.D.]

After Ptolemy, the Alexandrian school of astronomy produced only
copyists and commentators, the last of whom was Theon, who saw his
daughter Hypatia murdered and the library burned by fanatical mobs. It
only remains for us to see how the Greek system of astronomy, brought
to so great perfection in the _Almagest_, was neglected for many
centuries, and by whom it was at length rediscovered and made to live
again.




_VI. ASTRONOMY UNDER IMPERIAL AND CHRISTIAN ROME._

B.C. 46 TO A.D. 1000.


              _Vos O clarissima mundi_
    _Lumina labentem cœlo quæ ducitis annum._
                                     Georgic I.

No new school of astronomy arose under the Roman Empire, nor do we even
know of one Roman who devoted his life to the science. The genius of
this people lay in other directions, and Dante truly says:—

    ‘“Nature ordained in the world a place and a people
    for universal command ... to wit, Rome and her
    citizens or people. The which our poet too has
    touched upon right subtly in the sixth [Virgil, in
    the sixth book of the Æneid], introducing Anchises
    admonishing Æneas, the father of the Romans, thus:—

    “Others shall beat out the breathing bronze more
    softly, I do well believe it! And shall draw the
    living features from the marble; shall plead causes
    better, and trace with the rod the movements of the
    sky, and tell of the rising stars. Roman! do thou
    be mindful how to sway the peoples with command.
    These be thy arts: to lay upon them the custom of
    peace, to spare the subject and fight down the
    proud.”’[59]

------------------------------------------------------------------------
[59] _De Mon._ II. vii., “Temple Classics” edition.
------------------------------------------------------------------------

Yet there were some enthusiastic amateur astronomers in Rome, for
Cicero tells us of one who had felt old age to be no burden because he
was so eager over his astronomical studies, sitting up sometimes all
night to finish his calculations, and delighted when an eclipse he had
foretold came to pass.[60] This ardent amateur, Sulpicius Gallus by
name, had found such knowledge of practical value in his younger days,
when he was with the legions in Macedonia, for he had been able to
persuade the troops not to be alarmed by an eclipse of the moon which
was about to happen, explaining how it was due to natural causes; and
while the soldiers in the opposite camp were shrieking and moaning,
believing that the eclipse portended the death of their king, the Roman
soldiers remained quite calm. This was on the eve of the battle of
Pydna, in B.C. 168, a little before the time of Hipparchus.

------------------------------------------------------------------------
[60] _De Senectute._
------------------------------------------------------------------------

[Sidenote: Ovid B.C. 43-A.D. 17.]

[Sidenote: Virgil B.C. 70-19.]

[Sidenote: Manilius _c._ A.D. 10.]

[Sidenote: Cicero B.C. 106-43.]

In Cicero’s own life-time, and throughout the early days of the Empire,
it was the fashion to have at least a smattering of Greek astronomy.
Ovid tells legends of the constellations; Virgil, at his farm where he
lingered happily among his vines, his cattle, and his bees, studied the
varying aspects of the constellations in connection with the seasons
and the weather; Manilius wrote a long poem in five books on astronomy
and astrology; Cicero himself was quite learned in the subject, and
made a translation of Aratus, which had a great vogue.

Very popular also, both in classical and mediæval times, was his _Dream
of Scipio_, which was an imitation of Plato’s fable of the vision of
Er, in the _Republic_. The moral is that earthly fame is valueless,
since Earth itself is insignificant compared with the starry heavens,
but that those who practice virtue for its own sake shall return to
the stars whence their souls originally came. The youthful Scipio is
transported to the skies in a dream, and meets the souls of his father
and of the elder Scipio Africanus in “a radiant circle of dazzling
whiteness, which you have learned from the Greeks to call the Milky
Way.” There he sees “stars which we never saw from this place, and
their magnitudes were such as we never imagined, the smallest of which
was that which, placed upon the extremity of the heavens, but nearest
to the earth, shone with borrowed light.” But the shining globes of the
stars are so great that Earth seems to have contracted to a point, and
Scipio gazes at it, grieved.

“How long will your gaze be fixed on Earth?” cries Africanus. “Do you
not see into what temples you have entered?” and he points out nine
spheres which compose the whole universe. The outermost, in which
the stars are fixed, is most divine, and within this are seven, one
of which contains the planet called Saturn upon earth, the next the
glorious Jupiter, friendly and helpful to mankind, then Mars, ruddy
and terrible, and the next place in the middle region is held by the
sun, the leader, prince, and governor of all other luminaries, the soul
of the world, filling all things with his light. Venus and Mercury
follow him in their courses, like attendants, and in the lowest sphere
rolls the moon, kindled by his rays. Below this, all is mortal and
transitory, except the souls given to the human race by the grace of
the gods; above the moon all is eternal. Earth, which is at the centre
and forms the ninth sphere, is immoveable and below all the rest; and
all weights, by their natural gravitation, fall towards her.

Scipio then asks what is the sound which fills his ears, so loud and
yet so sweet? and he is told that he hears the music of the spheres,
which is too great for mortal ears, just as the sun is too bright for
human eyes to look upon. Yet those who make music upon Earth, with
strings or voice, like all others who follow heavenly pursuits, are
opening for themselves a path by which to return to the stars, the true
home of the soul.

[Sidenote: Strabo born _c._ B.C. 63.]

[Sidenote: Seneca B.C. 3-A.D. 65.]

[Sidenote: Pliny _c._ A.D. 23-79.]

[Sidenote: Proclus died _c._ 480 A.D.]

[Sidenote: Martianus Capella, 5th century A.D.]

[Sidenote: Simplicius 5th century A.D.]

Other famous Latin authors who wrote on astronomy were Strabo,
Seneca, and Pliny, who quote Eudoxus and Aristotle, Poseidonius, and
Hipparchus. When Ptolemy’s work was done there was no great writer to
popularize it. Three hundred years later Proclus writes a commentary
on it, and Martianus Capella mentions it, but Simplicius, in his
commentary on Aristotle’s _De Cœlo_, though he speaks of “the admirable
Ptolemy,” is evidently unacquainted with his work.

No Roman added anything new to astronomy, and the most precious parts
of their writings for the history of astronomy are some fragmentary
notes of early Greek astronomers whose original works are lost.

The practical use of astronomy for measuring time appealed, however,
to the Roman people. The most ancient Roman year (said to have been
introduced by Romulus) had only ten months, March being the first,
which explains why the ninth to the twelfth of our present months have
the names of September, October, November and December, as if they came
in the order of seventh to tenth. Two more months were added later,
and at some unknown date the old Octennial or 8-year Cycle was adopted
from the Greeks. This involved the use of intercalary months of varying
length, and the priests were entrusted with the business of arranging
them. But the priests thought it much more important that the length
of the year should suit their convenience than that it should conform
to the celestial movements, so they made it long or short according as
they approved or not of the persons holding office at the time; and by
the time of Julius Cæsar the calendar had fallen into such confusion
that March 25, which was supposed to be the date of the spring equinox,
came in the middle of winter!

[Sidenote: Julius Cæsar and Sosigenes B.C. 46.]

A drastic reform was necessary. Julius Cæsar called in the Alexandrian
astronomer Sosigenes, and gave the Empire the calendar which, with the
exception of one small reform made since, we still use. The moon was
thrown over altogether: there were to be no more intercalary months,
and every year was to be exactly like the last, except for the addition
of one day in every fourth year, so as to make the average year equal
to 365¼ days. Since the tropical solar year is only 11 minutes, 14
seconds shorter than this, many centuries would elapse before the
months of this calendar would depart from their proper seasons. March
25 was restored to the time of the vernal equinox, but the first
day of the new year was to be January 1, and Julius Cæsar gave his
own name to the old fifth month of Quintilis. Each month was to be
alternately of 31 and 30 days, except February, which would only have
its full complement of 30 days in the fourth year (Leap Year), and 29
every other year. This reform was regarded by some as an unwarrantable
interference by a despot. Cicero, when some one mentioned that the
constellation Lyra would rise at a certain hour, answered bitterly,
“Yes, if the edict allows it!”

Unfortunately, the simplicity of the scheme was a good deal spoiled
by the folly of Augustus, who could not bear that the month of his
predecessor should have 31 days while the next, the old Sextilis, which
he turned into August, named after himself, should have only 30. So he
made two months of 31 days come together, and took away a day from
February. Afterwards, Nero gave his name to April, and Domitian his to
October, but this was more than a long-suffering world could bear, and
the new names were gladly forgotten as soon as the tyrants were dead.

Although, therefore, Rome was obliged to apply to Alexandria, that is
to Greek astronomy, to carry out the project, it was Rome that gave us
the most correct and convenient calendar which exists, better in both
respects than that which had been used in Greece itself.[61]

------------------------------------------------------------------------
[61] The _average_ year was the same, 365¼ days, in the old 8-year
cycle of the Greeks, and also in the Calippic cycle, which did not come
into practical use. The average year of the Metonic cycle was longer,
and therefore departed further from the true tropical year.
------------------------------------------------------------------------

But alas! the celestial science, a willing servant as time-measurer for
the daily uses of humanity, a docile captive to adorn the triumph of
literature, was doomed to a baser servitude. It was in the early days
of the Empire, and all through the Middle Ages, that the pseudo-science
of Astrology was pursued with passion, and men spent their lives
in studying the paths of planets and positions of the stars, urged
solely by the delusive hope of being able therefrom to read the book
of fate and guide the lives of their superstitious clients. From
Chaldea, its ancient home, came the most famous astrologers, but their
art was soon learned in every country of Europe, and its professors
were sought after by peasants and kings—now reviled and banished as
impious and leagued with devils, now loaded with honours and rewards,
revered, hated, welcomed, forbidden, but always believed in. Although
when Christianity was established the seven planets could no longer
be regarded as great gods ruling over the lesser gods of the stars,
they were still thought to be mighty revealers of fate. Each had his
special attributes and influence over man: the fiery colour of Mars
no doubt suggested the warlike and hostile spirit ascribed from time
immemorial to this planet-god; the slow motion of Saturn in his distant
sphere gave an impression of a mournful morose being, the “frigida
Saturni stella” of Virgil; Venus was the planet of love; the sun, of
honour and power, and so forth. Each planet was also mysteriously
connected with a colour, and, the alchemists said, with a metal; the
sun with gold, the moon with silver, Saturn with pale heavy lead, etc.
Each also influenced a special part of the body: thus, if Mercury were
unfavourably placed at the moment of a child’s birth it would be liable
to suffer from lung-disease; the moon’s position affected the brain;
the sun’s the heart, etc.

As the planets had distinct and often contrary influences in different
positions, it was necessary, in determining a man’s fate, to consider
the aspect of the whole heavens, especially at the moment of his birth,
but horoscopes were also cast for any period in his career, past,
present, or to come, enabling him to guard against threatening evils
or bad tendencies, and to seize favourable opportunities. The method
was as follows: the sky-sphere, as it appeared at the given time and
place, was divided into twelve “houses,” by drawing meridians (called
“circles of position”) 30° apart. The house just about to rise on the
eastern horizon was called the “ascendant,” and was the first and most
important, planets situated there having more power than anywhere else;
but each house had its special significance, the second (just above the
eastern horizon) being the House of Riches, the seventh of Marriage,
the twelfth of Enemies, etc. The kind and the strength of each planet’s
influence depended mainly upon the house in which it happened to be,
and was strongest when the planet was in its own house and also in its
favourite zodiacal sign. The sun was considered to be most at home in
Leo, the moon in Cancer, and each of the other five planets owned two
of the remaining signs. Another important point was the “aspect” of the
planets with regard to one another, that is, their angular distance
apart on the sky-sphere. If Mars and Jupiter, for instance, were in
“opposition,” _i.e._ 180° apart, the portent was unfavourable, but in
“trine” or “sextile” aspect (120° or 60° apart), favourable.

It is evident that for casting horoscopes it was necessary to be able
to calculate for any given time or place the positions of the heavenly
bodies; and for this the skies must be watched, and the movements
known of the stars, of sun and moon, and of planets. To this extent,
therefore, an interest in genuine astronomy was kept alive; but on the
other hand, the system fostered belief in the overwhelming importance
of Earth in the Universe, and the existence of the heavenly bodies
for the sole purpose of ruling and foretelling human destinies: no
one cared to inquire what were the underlying laws, and what the real
nature, of the heavenly phenomena.

Closely allied to this superstitious belief in planetary influences,
was the dread of comets, meteors, and eclipses, which were everywhere
regarded as omens. It was in vain that Seneca urged the greater
importance of investigating the nature of the heavenly bodies about
which something was already known, and of trying to solve the problem
worthy of highest consideration, viz. whether the earth, as some had
asserted, was turning rapidly, or was stationary in a turning World.
His very protest, as well as his lengthy dissertation on comets, shows
how far less interesting, alike to philosophers and public, were the
ordered courses of stars and planets, than the startling apparition of
such rare objects as that great “hairy star” which, appearing suddenly
during the games instituted by Augustus after the assassination of
Julius Cæsar, was thought to be the soul of the dead Emperor. Augustus
erected a temple in its honour.

Rome, considered as the metropolis of the dominant temporal power,
failed to encourage astronomy; Rome as the centre of the spiritual
power directly discouraged it.

[Sidenote: Cosmas _c._ 540 A.D.]

[Sidenote: Augustine 354-430 A.D.]

In the fourth and fifth centuries after Christ “the old heathen
theory” that Earth is a sphere was opposed by some of the Fathers,
as inconsistent with certain expressions in the Bible; and in the
sixth an Egyptian monk, Cosmas Indicopleustes, formulated a scheme of
the Universe according to which the Jewish Tabernacle was a type and
pattern of the World. The earth is the flat oblong floor, surrounded
by four seas; these are enclosed by four massive walls which support
a roof (the firmament or sky), and above this live the angels, who
move the sun, moon, and stars across the firmament, and let down rain
through its window. This childish cosmogony, supposed to be in entire
accordance with Genesis, Isaiah, and the Psalms, bears a curious
similarity to one of the oldest “heathen theories” of all, born in the
land where Cosmas lived.[62] Saint Augustine, however, author of the
paralysing doctrine: “Nothing is to be accepted save on the authority
of Scripture,” does not seem to have considered belief in a spherical
Earth forbidden, but it was to him a matter of perfect indifference,
while he upheld as an article of faith that in no case could any
antipodean inhabitants exist. For they could not be descendants of
Adam, nor ever hear the Gospel, since everyone knew the torrid zone to
be an impossible barrier between north and south. Another favourite
Church doctrine was that Jerusalem was the centre of the earth: this
idea, which it will be remembered has a place in Dante’s cosmogony, was
based on the words in Ezekiel:[63] “This is Jerusalem: I have set it in
the midst of the nations and countries that are round about her.” Good
bishop Arculf, and other pilgrims, were shown a pillar “on the north
side of the holy places, and in the middle of the city,” which marked
the exact spot, and were told in proof of the assertion that at midday
at the summer solstice this pillar cast no shadow! How this proved its
central position is a mystery, and if true the pillar must have been
deplorably crooked, for the sun can never pass overhead in Jerusalem,
in a latitude of nearly 32° north.

------------------------------------------------------------------------
[62] See p. 45.

[63] _Ezekiel_, v. 5.
------------------------------------------------------------------------

The Church, like the State, saw that astronomy had one use, and
applied, like the State, to Greek astronomy for a calendar. It was
necessary that the ecclesiastical calendar should be luni-solar, since
Easter, which corresponds with the Jewish passover, must fall on the
Sunday following the first full moon after the Vernal Equinox. By 325
A.D., when the Council of Nice was held, at which this question was
settled, the Vernal Equinox fell on March 21 instead of March 25,
owing to the neglected eleven minutes in the Julian year. March 21 was
therefore adopted by the Church as the date of the equinox, which was
assumed to remain constant; and the old luni-solar cycle of Meton was
used, and still is used in all churches which celebrate Easter, as a
basis for the ecclesiastical calendar.

The custom of reckoning years forwards and backwards from the birth of
Christ was first introduced by a Roman abbot, Dionysius Exiguus, in the
sixth century, but it did not become general in Christian countries
until the ninth century. Dionysius adopted as the first day of the
epoch, not January 1, but March 25, the old Roman date of the vernal
equinox. This was because it was Annunciation Day, and it was a belief
of the Middle Ages that the Annunciation and also the Crucifixion
actually took place on this day, and also that the Creation began on
the same date.

[Sidenote: Martianus Capella 5th cent. A.D.]

[Sidenote: Cassiodorus _c._ 530 A.D.]

[Sidenote: Boëthius died 525.]

At the break-up of the Roman Empire some fragments of classical
learning were saved from the wreck, mainly in the text-books of the
“heathen” writers, Capella, Cassiodorus, and Boëthius. These were
preserved by the Church, now the only repository of learning. The
secular instruction given to churchmen included astronomy, for while
the “Trivium” comprised the three elementary sciences of Grammar,
Rhetoric, and Dialectic, the “Quadrivium” comprised the four advanced
sciences of Arithmetic, Astronomy, Geometry, and Music. But only a
mere smattering of the “Quadrivium” was taught in this period, and
scarcely more of astronomy than was necessary for determining the date
of Easter. The intimate knowledge and ingenious theories of the Greeks
concerning the celestial motions interested no one any more.

[Sidenote: Charlemagne 732-814.]

[Sidenote: Isidore died 636.]

[Sidenote: Bede _c._ 673-735]

[Sidenote: Fergil, 745.]

[Sidenote: Dicuil, 825]

From the seventh century, however, the ignorance began to be less
dense. Charlemagne established many schools, and there were enlightened
monks here and there—Saint Isidore of Seville, the Venerable Bede,
and Irish scholars like Fergil and Dicuil—whose teachings show that
the elements of astronomy as taught by the Greeks were not totally
forgotten everywhere. From the beginning of the ninth century all
famous monasteries had schools for laymen as well as for monks.

In Italy the darkness was never quite so deep as in northern Europe,
for traditions of classical culture never quite died out. And although
throughout the long period from Ptolemy to the end of the tenth
century, astronomy had been almost completely neglected in Europe, the
way was slowly being made plain for a great revival. The ideal Empire,
governing the whole world from the Eternal City, and the ideal Church
making all men brothers, though neither has ever existed in fact, did
so in men’s minds, as we see clearly in Dante, and both exercised a
powerful influence. The Roman Empire and the Roman Church did impress
a kind of unity on Europe as it grew: there was one civilization, one
religion, one language in which new thoughts could be conveyed to all.
Thus the ground was prepared, and whenever a new school of astronomy
should arise or be imported, it would not remain the property of one
nation surrounded by barbarians, but might at once be shared in and
advanced by the whole of Europe.




_VII. ARAB ASTRONOMY._

A.D. 750 TO 1250.


ARAB ASTRONOMY.

Once more the scene changes. While European science is at low ebb,
if we look to the banks of the Tigris, not many miles from the ruins
of ancient Babylon, we find the centre of a new and famous school of
astronomy.

[Sidenote: Al Mansur 753-775 A.D.]

From the deserts of Arabia an immense empire had arisen, which in less
than a century spread eastwards as far as India, and westwards to
Morocco and Spain. Its first capital was Damascus, but in 755, after
the defeat of the Omeyyad dynasty, the new Caliph fixed his capital
at Baghdad, the wondrous city of the Thousand and one Nights. This
Caliph was the renowned Al Mansur. To his court there came one day a
scholar from India, who was skilled in the knowledge of the stars, and
he laid before the Caliph a book which treated of things celestial and
showed how to foretell eclipses. Al Mansur was profoundly interested,
and ordered a translation of the book to be made into Arabic. The
astronomical system of the Hindus was at that time very similar to the
Greek, and there can be no doubt that Greek astronomy had found its way
to India several centuries before this.

[Sidenote: Haroun al Raschid 786-809 A.D.]

Shortly after this the writings of Greek philosophers and astronomers
were brought to the court at Baghdad. They had been carefully
preserved, copied, and translated into Syriac, by Nestorian monks in
some of the many monasteries which were founded in Persia and other
countries of the East when these heretic Christians were driven out
of Europe in the fifth century; and many of the Court physicians of
Baghdad came from a Nestorian school of medicine. Haroun al Raschid,
son of Al Mansur, gave orders for Ptolemy’s _Syntax_ to be translated
into Arabic, and it now received its name of _Almagest_: several other
translations were made later, and Aristotle was eagerly studied. This
Caliph sent an embassy to Charlemagne, and among the presents sent by
the East to the West were an elephant and a clepsydra.

[Sidenote: Al Mamun 813-833 A.D.]

Al Mamun, son and successor of Haroun Al Raschid, is said to have
learned astronomy under a Persian teacher. He also added to his
father’s library, and one of the terms of a treaty he made with
Michael, the Greek emperor, was that a collection of Greek writings
should be made throughout the empire, and forwarded (originals or
copies) to Baghdad. Moreover, he was not content with merely reading
astronomy, Greek, Persian, or Hindu: he ordered Ptolemy’s estimate
of the size of the earth to be tested, by measuring an arc of a
meridian in his own country, and he founded a splendid observatory
in the province of Baghdad. The instruments were of the same kinds
as the Alexandrian, but they were larger, and better made, and the
circles were more accurately divided. The Arab astronomers were good
observers, and among them for the first time we hear of astronomers
winning fame by skill in instrument making. Their dials were superior
to those of any other race, and they made some important improvements
in mathematics, which were immensely useful to astronomers. One great
service was the introduction of the decimal notation, which they
learned from the Hindus.

Astrology is forbidden by the Koran, but it was practised eagerly,
nevertheless, by the Arabs, who constructed tables for this purpose,
and made improvements in the methods used.

Traces of Arab contributions to astronomy survive in our words “zenith”
and “nadir,” and “almanac”; our word for a “cipher” is the Arabic
“zifra,” and indicates the main advantage of the decimal notation in
arithmetic; while “sine” is the Latin translation of an Arabic word,
and reminds us of the great improvements made in trigonometry.[64]

------------------------------------------------------------------------
[64] Arabic _gib_ = Latin _sinus_, a fold; _i.e._ the chord folded in
two.
------------------------------------------------------------------------

[Sidenote: Alfraganus _c._ 840 A.D.]

[Sidenote: Albategnius _c._ 900 A.D.]

[Sidenote: Abul Wefa 940-998.]

Among the many names of Ptolemy’s successors at Baghdad, strange and
uncouth to our ears, the three most famous are Mohammed ebn Ketir
of Fargana, Mohammed ben Geber Albatani, and Mohammed Abul Wefa al
Buzjani, which became known to the West under the shortened forms of
Alfraganus, Albategnius, and Abul Wefa.

[Sidenote: Ebn Jounis died 1009.]

Egypt too had her Arab school of astronomy, as she had had her Greek.
A little later than Abul Wefa, Ebn Jounis drew up the famous Hakemite
Tables of the sun, moon, and planets, under the patronage of the Caliph
Hakem of Cairo.

At the western end of the Arab dominions there were centres of
intellectual activity in Morocco and southern Spain. Cordova, the city
of the marvellous mosque, had also, in the tenth century, an Academy,
and a library which rivalled that of Baghdad; and here, in the midst of
almost ceaseless public strife and agitation, in a strangely mingled
atmosphere of cultured refinement unknown to the rest of Europe, and
of ferocious barbarism, of tyranny and tolerance, heroic deeds of
chivalry and treacherous intrigues, there lived and dreamed and worked
men of science and philosophers, poets, and artists.

[Sidenote: Arzachel _c._ 1080.]

[Sidenote: Averroës 1126-1198.]

[Sidenote: Al Betrugi _c._ 1150.]

[Sidenote: Abul Hazan _c._ 1200.]

The best known of the Spanish Arabs whose names are connected with
astronomy are Arzachel, who drew up the Tables of Toledo; Averroës, the
great philosopher, author of _De Substantia Orbis_, and a commentary on
Aristotle’s Metaphysics, who saw “a black spot on the sun” on the day
he had predicted a transit of Mercury; and Al Betrugi (or Alpetragius)
who wrote on the Spheres. There was also a certain Abul Hazan, a
renowned geographer, who travelled across North Africa, and made a
catalogue of 240 stars, including some not given by Ptolemy.

Of all the astronomical writings of the Arabs, one of those which
became earliest and best known in Europe was the _Elements of Astronomy
and Chronology_ of Alfraganus. This was actually used by Dante as his
favourite text-book, and he mentions it in the _Convivio_. I shall
therefore give a short account of its contents, following the edition
of Golius, printed in Arabic and Latin at Amsterdam in 1669.

In the first chapter Alfraganus gives an account of the calendars used
by different nations—Arabs and Berbers, Syrians, Romans, Persians, and
Egyptians. After this he plunges at once into a description of the
Universe, as portrayed by Ptolemy, and follows his master so closely
that his book is almost a much-abridged and simplified _Almagest_, with
a few additions, and with all the mathematics left out.

It is accepted almost without dispute among learned men, says
Alfraganus, that the sky is spherical, and rotates on two fixed poles,
one north, one south. This is proved by the observed movements of the
stars. Equally undisputed among the learned is the fact that Earth and
water together form a globe, which is surrounded by air. The spherical
form of Earth is proved by the fact that phenomena such as lunar
eclipses and shooting stars are seen at a later hour by observers in
the East, and by the changing height of stars above the horizon as one
travels north or south. Earth is at the centre of the universe, and is
but a point compared with the heavens.

There are two principal celestial motions: (1) the “prime motion” which
causes the whole sky to revolve with every celestial body, and produces
day and night; (2) the proper motions of the sun and other stars in the
opposite direction and round other poles. The great circle of the first
motion Alfraganus calls the Equator of the Day; that of the second, the
Star-bearing Circle, _i.e._ the zodiac, or more precisely, the ecliptic.

The twelve zodiacal signs are then described, with the division of
each into degrees and minutes, the positions of the equinoxes at the
beginning of Aries and Libra, and of the solstices at the beginning of
Cancer and Capricorn. The Colure is described as a great circle cutting
the zodiac (_i.e._ ecliptic) and equator at the points where they are
furthest apart (_i.e._ at the solstices). This greatest difference
was found by Ptolemy to be 23° 51′ but according to the measurement
ordered to be made by Al Mamun of pious memory, which was carried out
by a number of experts, it is 23° 35′. This value is adopted and quoted
subsequently throughout the book of Alfraganus.

Alfraganus then proceeds to explain very clearly how the movements of
sun and stars appear from different latitudes on Earth—on the equator,
at stations further north, and finally at the pole. He shows how it
happens that on the equator day and night are always of equal length,
and the sun passes exactly overhead twice a year; whereas day and night
vary more and more in length, according to season, as one travels
further north, and the sun is lower; until at last at the pole the year
consists of one long day and one equally long night, the celestial pole
is in the zenith and the celestial equator on the horizon, so that the
sky revolves like a mill-stone (_i.e._ the stars do not rise and set,
but trace out horizontal circles, like a wheel which is not upright but
flat on the ground).

The circumference of Earth, as determined by Al Mamun of glorious
memory, is 20,400 miles, and the diameter, therefore, is nearly
6500.[65] Alfraganus deduces from this the area of the whole Earth and
also of the habitable portion of Earth. The latter extends only from
the equator to 66° 25′ North, and its longitude at the equator is equal
to 180° or 10,200 miles, at the northern limit to 4080 miles. This is
divided into seven “Climates,“ as in Ptolemy’s Geography, the first
lying a little north of the equator. Alfraganus gives for each the
length of the longest day, the height of the pole above the horizon,
the extent of territory, and the principal regions and towns comprised.
He admits that south of the first climate as far as 0° is some land,
surrounded by sea, and sparsely inhabited, and north of the seventh
climate are a few towns, but these are of no account.

------------------------------------------------------------------------
[65] The Arabian mile was equal to 4000 “black cubits,” and if this is
the Egyptian and Babylonian cubit, the values are rather too large,
being in round numbers 26,500 and 8,500 English miles, instead of
25,000 and 8000.
------------------------------------------------------------------------

Our author treats next of the risings and settings of the zodiacal
signs, and of the division of the day into 24 equal or 24 “temporary”
hours (see p. 26).

After this, the unanimous opinion of wise and learned men concerning
the spheres is duly set forth in seven chapters; how there are eight
great Orbs, the smaller enclosed within the greater, the star sphere
being the outermost and largest of all; how epicycles are fixed in
these; how only the star sphere has its centre exactly in Earth,
the others being slightly eccentric; what are the positions of the
poles and centres of the great spheres and the small epicycles, their
relative sizes, and their different velocities as they turn; finally,
how well the system represents the movements of sun, moon, stars, and
planets. The moon’s mean daily motion, resulting from a wonderful
combination of five circular motions, amounts to about 13° 11′; the
sun’s is 59′, and he completes a revolution in 365¼ days “less an
insignificant fraction.” (This being a popular treatise Alfraganus
apparently thinks it unnecessary to state the length of the year
more precisely). The sluggish motion (“motus tardissimus”) of the
star sphere, which is communicated to all the rest in addition to their
own motions, is 1° in a century, according to Ptolemy, so that it
completes a revolution in 36,000 years.

Coming now to the fixed stars, their number, and brightness, Alfraganus
does not copy Ptolemy’s great catalogue, but informs us that learned
men (“sapientes”) did number all the fixed stars as far south as they
could see in the 3rd climate, and divided them according to magnitude
into six classes. “To the first class they assigned the bright and
shining stars such as Canis (Sirius) and Procyon, Vultur Cadens (Vega)
and Cor Leonis (Regulus). Stars a little less bright they called second
magnitude: such are Alfarcatein and Benet Naax,” Arab constellations
which the Latin version describes as the two bright stars of Ursa
Minor, and those brilliant ones in the tail of Ursa Major. Thus they
proceeded with the other magnitudes, the smallest measured being of the
sixth magnitude. The number of stars in each class is given, and the
total of 1022;[66] then a list of the 15 first-magnitude stars, which
are the same as Ptolemy’s (See p. 155). This is followed by a list of
the Arab “Mansions of the moon.”

------------------------------------------------------------------------
[66] The Catalogue of Hipparchus is said to have contained 1080 stars,
but Ptolemy’s has only 1022.
------------------------------------------------------------------------

[Illustration: Fig. 36. Method (erroneous) of estimating planetary
distances, described by Alfraganus.

The distance _E A_ being known, and _E p_ being assumed equal to it,
the distance _E a_ can be calculated from the known ratio _E a_: _p a_.]

So far (with the exception of the mansions of the moon) the Arab
writer has followed the Greek, but we have now reached a point where
he diverges. Ptolemy, he says, only tells us the distances and sizes
of the sun and moon, and said nothing about the other heavenly bodies;
but if we suppose the greatest distance of the moon to be the same as
the least distance of Mercury, and from this calculate his greatest
distance (for the ratio is known), and if we proceed in the same way
with Mercury and Venus, we shall find that the greatest distance
of Venus equals the least distance of the sun as given by Ptolemy.
Ptolemy’s least distance for the sun, which was totally wrong, was
1160 Earth-radii: the greatest distance of Venus, calculated in this
way from Ptolemy’s figures, was 1150. Alfraganus takes this unlucky
coincidence as an indication that there is only just sufficient space
between each sphere and the next to allow their respective epicycles
to pass one another, and upon this entirely erroneous assumption he
proceeds to lay down the distances of each planet from the earth,
and finally of the stars, which are all supposed to be at the same
distance, equal to the greatest distance of Saturn.

Who first suggested this method of estimating distances we do not know:
the first mention of it occurs in Europe in the fifth century A.D. The
following table shows the distances obtained in this way:—

    GREATEST DISTANCE.

                      _In Semi-Diameters of Earth._
    Moon                             64⅛
    Mercury                         167
    Venus                          1120
    Sun                            1220
    Mars                           8876
    Jupiter                      14,405
    Saturn and Stars             20,110

In this, the moon’s distance is approximately correct, but the sun’s
is not much more than one-twentieth of its true value. To set the
stars at a distance of only twenty thousand times Earth’s semi-diameter
seems to us to bring them very close,[67] but they would still be
beyond measurement by naked eye methods, so it is no contradiction to
Alfraganus’ earlier statement that Earth is a point compared with the
heavens.

------------------------------------------------------------------------
[67] Earth’s diameter, and even Earth’s distance from the sun, is too
small a unit. Light, travelling 186,000 miles a second, takes 4¼ years
to reach us from the nearest star.
------------------------------------------------------------------------

The Arabs also believed that they had succeeded in measuring the
apparent diameters of the planets and even of the points of light which
are all we can see of stars, so Alfraganus gives the accepted sizes of
all. I give them below in descending order of size. The modern values
in the third column show how false were the results obtained by this
mistaken method.

                         DIAMETER: EARTH = 1.

                          _Alfraganus.                 Modern Values._
    Sun                        5½                               109½
    The 15 first-magnitude           { Arcturus, Sirius,
       stars                   4¾    { Spica, and others, much
                                     { larger than the sun.
    Jupiter                    4⁹/₁₆                             11
    Saturn                     4½                                 9
    Other stars, in order of         { Various. Some certainly
       magnitude, 2nd to 6th  ...    { larger than the sun.
    Mars                       1⅛                                 ½
    Earth                      1                                  1
    Venus                     ³/₁₀                               ⁹/₁₀
    Moon                      ⁵/₁₇                                 ¼
    Mercury                   ¹/₁₈                                 ⅓

In the above table the size of the moon (whose parallax had been found
by the Greeks) is the only one which is nearly right. The sun is far
too small, and so are the stars. We cannot yet know with certainty the
diameter of any star, but they are all comparable with the sun, and
many are enormously larger.[68] As their distances are all different,
some of the brightest may be comparatively small, and some of the
faintest the largest of all.

------------------------------------------------------------------------
[68] It is impossible to measure the diameter of any star, even with
the help of the most powerful telescopes, but in the case of a double
star at a known distance the movement of the components as they
travel round their common centre of gravity enables us to determine
the gravitational force they exercise on each other, and thus their
combined mass; and their spectra give some idea of their density. For
instance, the mass of the double star Alpha Centauri is nearly twice
that of our sun; and as the components appear to be about equal to
each other, and both show a spectrum resembling that of the sun, we
may conclude that Alpha Centauri consists of two stars, each of which
has about the same diameter as our sun. Arcturus has a diameter far
greater, some say ten times, some not less than twenty-five times as
great as the sun!
------------------------------------------------------------------------

The Arabs took a backward step in adopting these imaginary
measurements, for Hipparchus had recognized that only the moon was near
enough to measure, and although Ptolemy accepted Aristarchus’ value for
the sun, he distinctly stated that the planets had no parallaxes and he
could not tell their distances.

The next four chapters describe briefly the risings, settings, and
meridian transits of stars as seen from different latitudes on Earth;
the heliacal risings and settings and the conjunctions with the sun
of planets, stars, and moon: the phases of the moon and the direction
of her horns at different times of the year. Parallax is then clearly
defined and discussed.

A description follows of the earth’s shadow, thrown by the sun into
space—its tapering form, its position, always pointing away from the
sun, its width at the distance of the moon, and its length according
to Ptolemy. This is stated to be 268 times Earth’s semi-diameter,
which is nearly correct,[69] for although Alfraganus believed (from
Ptolemy’s erroneous parallax) that the sun, was much nearer than it
really is, it followed from this—since the size was deduced from
the distance—that he also thought it much smaller, and the length of
a shadow thrown by any dark body is longer the nearer it is to the
light-source, but shorter, the smaller is the light-source.

------------------------------------------------------------------------
[69] The mean length of Earth’s shadow (which varies a little with
her distance from the sun,) is 857,000 miles, or 216 times her
semi-diameter.
------------------------------------------------------------------------

[Illustration: Fig. 37. Earth’s Shadow.]

The two last chapters are devoted to eclipses, lunar and solar, and
Alfraganus points out that, unlike lunar eclipses, eclipses of the sun
vary in duration and magnitude according to the place on Earth from
which they are viewed.

The book concludes: “Enough having now been said concerning the
eclipses of sun and moon, by the goodness of God we have been enabled
to bring this writing to an end; and for this _Deo Laus et Gloria_.”

The time at which Alfraganus lived is not precisely known, but it seems
to have been in the first half of the 9th century, since from internal
evidence he wrote after, but probably not much after, the death of
Al Mamun. His name indicates that he was a native of the beautiful
and fertile country, shut in by lofty mountains, which lies on either
side of the ancient river Jaxartes. He was surnamed the Calculator,
and wrote on sun dials and the astrolabe, but we do not know of any
observational work of his.

Later Arab writers although they all continued to base their work on
that of Ptolemy, improved on some of his estimates. Albategnius began
his book “On the Number and Motions of the Stars” by saying that having
studied Ptolemy’s _Syntax_ and mastered the Greek methods, and having
noticed some errors in the positions of the stars, he felt impelled
to add to Ptolemy’s observations, as the latter had added to those of
Abrachis (Hipparchus), for it is not given to man to attain perfection.
He gives a much more accurate value for precession than Alfraganus had
done, who merely copied Ptolemy, for he makes it 54½ seconds yearly,
or one degree in 66 instead of in 100 years. His tropical year,
too, is only two minutes shorter than the modern value, so that he
improved upon Hipparchus in this respect; and he made the discovery
which Ptolemy missed, the motion of the sun’s apogee. He merely notes,
however, that the position found by himself differed from that given in
the _Almagest_, so it is doubtful whether he realized his discovery, or
merely thought that a large error had been made.

Although some of Ptolemy’s values were thus corrected by the Baghdad
astronomers, no change was made in his theory of epicycles and
eccentrics, which all accepted as having a concrete existence, partly
because at first they did not distinguish between these and the spheres
discussed by Aristotle, which he had described as formed of the same
material as the planets. As Ptolemy does not explicitly state that his
circles were only symbols, this is not surprising. They are formed, say
the Arabs, of the fifth essence al-acir (the æther); and they conceived
the epicycle as gliding over the outer surface of the deferent, like a
small soap-bubble on the back of a big one. This notion, coupled with
Ptolemy’s erroneous distance of the sun, misled them, as we have seen,
into their imaginary discovery of planetary distances.

[Sidenote: Tabit ben Korra 826-901.]

It was also partly due to Ptolemy’s unfortunate habit of adopting
the doubtful or merely provisional results of his predecessors, and
representing them as well established and confirmed by himself, that
they fell into another error. Tabit ben Korra, noting the discrepancy
between the Greek and the Arab value of precession, investigated
the question, and put forward a theory that the motion varies both
in amount and direction. In his book “On the Motion of the Eighth
Sphere” he describes an elaborate apparatus which he had invented to
account for this variation, but he is very modest about it, and after
narrating the results obtained by others, and how they had left them to
be judged by posterity, he adds “And this is what we have done, with
God’s blessing.” Then follow his figures and tables. This imaginary
discovery was accepted by some of the Arab school, and it appears in
many mediæval tables, instead of precession, under the name of the
“trepidation.”

The belief in the material reality of the spheres caused the Arabs
to add a ninth sphere to the eighth of Ptolemy and Alfraganus, for
they thought it was enough to demand of the eighth that it should
carry all the stars and give them their slow movement of precession
(or trepidation). This ninth sphere, therefore, enveloped the whole
universe: upon it were fixed no epicycles, no stars, no planets, but it
originated the “prime motion” by turning once in a day and night, and
communicating this revolution to all the inner spheres. It became known
in mediæval astronomy as the Primum Mobile or first moving.

[Sidenote: Nasir-ed-din 1201-1274.]

[Sidenote: Alfonso 1223-1284.]

The Baghdad school of astronomy came to an end with Abul Wefa in
998, and the Spanish schools died out when Seville and Cordova were
captured by the Christians in the thirteenth century; but the impetus
given to the study of Greek astronomy and astronomical observation was
carried on by other nations. In Persia a fine observatory was founded
by Nasir-ed-din; in Spain the Christian king, Alfonso X, ordered tables
to be drawn up to replace those of Arzachel, and the _Libros de Saber_
to be compiled. The movement in Persia was short-lived, but in Europe
the revival of astronomy had begun.




_VIII. THE RETURN OF GREEK ASTRONOMY TO EUROPE._

A.D. 1000 TO 1300.


       “He hath made everything beautiful in His time; also He hath set
    the infinite in their heart.”

In the whole cycle of the changing year there is no moment so wonderful
in northern climes as that which comes in early February, when winter
is not yet past, but for the first time the promise of spring is felt
in the air. Not a leaf has unfolded its green, but the swelling buds on
the trees make a purple flush all over the woods, the blackbird sings
an exultant strain, and in some sheltered copse you may find a delicate
daring primrose already in bloom.

Such a moment in the history of Europe was the year 1000 Anno Domini.
After the apathy, the ignorance, the despair of the Dark Ages, a new
spirit began to breathe hope into the hearts of men. A love of beauty,
a new religious fervour, a passionate desire for knowledge took
possession of them. Yet it was nearly a hundred years before the great
universities which were one expression of this new spirit sprang up
in Paris, Bologna, Oxford, to be followed later by similar centres of
intellectual activity in all parts of Europe.

By the end of the twelfth century it is said that there were 100,000
students in Bologna. A large number were foreigners from many lands,
for as Latin was the universal tongue in education, all nations could
understand each other, and scholars often wandered from one university
to another, attracted by the fame of some great master. Similarly the
doctors would teach first in one town and then another. Men of all
ages and classes met together, for among the students were young boys
and elderly ecclesiastics, poor scholars who begged their bread, and
rich nobles who came with a tutor, a chaplain, and a whole suite of
servants. There were no colleges or even lecture-halls: the students
joined together in small groups to take a house and share expenses, and
the professor lectured in his own house, or in a hired room, or, if the
audience was large, in a city square, speaking from an open-air pulpit.
All were united in the ardent pursuit of learning, and none complained
if the floors were merely covered with straw, and the lectures, which
often lasted three hours, began before sunrise on winter mornings in
rooms which had no light and no fire. Was it not enough that when
leaving at the end of university life one was technically said to be
“going home a wise man”?

One cause of this intellectual fervour was the influence of Arab
culture, with which Europe came into contact through the crusades,
and through the Saracens in Sicily, and the Moors in Spain. For this
reason astronomy and astrology took a high rank among the new studies.
To distinguish between the two is quite a modern idea, and in mediæval
times either name was used indifferently to cover both subjects. In
Bologna university in the thirteenth century an important school of
medicine and arts arose, through Arab influence, and the Arab doctors
of medicine introduced the system of astronomy which they had learned
from the Greeks. “A doctor without astrology,” it was said, “is like
an eye that cannot see;” and before prescribing for a patient it was
thought quite as important to determine the positions of the planets,
as the nature of the disease. By the beginning of the fourteenth
century there were salaried professors of astrology in Bologna, and
they were more highly esteemed than any other professors except those
of philosophy.

[Illustration: A MEDIÆVAL ASTRONOMER. [_To face p. 200._

_From a painting by Gerard Dow._]

[Sidenote: Cecco d’Ascoli _d_. 1327.]

One of their duties was to provide “judgments” (_i.e._ to cast the
horoscope) gratis for students. But the dignity was a perilous one.
Legitimate prediction by astrology bordered close on necromancy, which
was banned by the Church, and one of Bologna’s most famous professors
in astrology, the learned Cecco d’Ascoli, was burned at the stake in
Florence in 1327 for the crime of sorcery.

Astronomy, like other subjects, was taught chiefly by lectures and
“repetitions,” or classes for catechizing the students on what they had
already heard. Books could also be had, though they were dear, on hire
or purchase, from the university “stationers” or librarians.

The first books on Greek astronomy which found their way into European
universities were Latin translations of Arabic commentaries and
paraphrases of Aristotle, which travelled from Moorish academies in
Spain to Paris. The astronomical treatises with strange technical terms
in Arabic were hard work to translate, especially when they had already
passed through several languages, as often happened. Thus it was
possible to possess a work of Aristotle which was a Latin translation
of a Hebrew translation of a commentary upon an Arabic translation of a
Syriac translation of the original Greek text!

[Sidenote: Urban IV., pope 1261-1264.]

But meanwhile some of Aristotle’s works in the Greek entered Italy from
the East, as a result of the crusading conquest of Constantinople in
1204. The first translations of these into Latin were very poor, but
later on St. Thomas Aquinas, with the help of Pope Urban IV., had a
better version made.

[Sidenote: Frederick II. 1194-1250.]

[Sidenote: Sacrobosco died _c._ 1256.]

[Sidenote: Roger Bacon _c._ 1214 to _c._ 1294.]

It was long before a good Latin version of Ptolemy’s _Almagest_ could
be obtained. A translation was made from the Arabic in 1230, at the
bidding of the Emperor Frederick II., who did much, at his Sicilian
court, to encourage Arab literature, but this translation was not
much known or used.[70] The teachings of the _Almagest_ became known
chiefly through popular expositions such as those of Alfraganus,
Albategnius, and John Halifax of Holywood, an English monk who became
famous under his Latinized name of Sacrobosco. He was not an astronomer
but had studied Greek and Arab writings, and finding that the study of
astronomy was neglected because books on the subject were difficult
both to procure and to understand, he compiled a useful handbook, which
became widely popular and remained so for several centuries. Several
other writers, notably Roger Bacon, wrote on the spheres, on the use of
astrolabes, and on astrology. The books prescribed in Bologna for the
course in Astrology and Mathematics were as follows:—

------------------------------------------------------------------------
[70] It was also translated from Arabic into Latin at Toledo, in 1175.
------------------------------------------------------------------------

    A work on Arithmetic or Algebra.
    Euclid, with a thirteenth century commentary.
    The “Theorica Planetarum,” which was either a free translation
       of Ptolemy’s _Almagest_ or an exposition of its principles.
    The Alfonsine Tables.
    The Canons of De Lignières (of Amiens, 1330 A.D.),
       _i.e._ rules for the use of astronomical tables to determine
       the motions of the heavenly bodies.
    Portions of the Canon of Avicenna (the Arab philosopher).
    A treatise on the Astrolabe by a Jewish astrologer of the
       ninth century.
    A treatise on the Quadrant.
    The astrological works of Ptolemy, with a commentary.
    A book by Alchabicius (fl. _c._ 850 A.D.),
       probably his work on astrology.
    A book on astrological medicine.

[Sidenote: Alfonso X. 1223-1284.]

From the above we gather that a past master in Astrology would
understand the elements of mathematics, and all the astronomy that
Ptolemy’s translator or commentator could teach; that he had learned—at
least in theory—the use of astronomical instruments and tables, and
a good deal of astrology, including its use in medical practice.
The tables were intended mainly for astrological predictions. The
standard Alfonsine Tables had been drawn up in 1252 by Christians,
Jews, and Moors, under the direction of Alfonso X. king of Castile.
They contained lists of positions of the planets, dates of Easter
moons, “golden numbers” and “dominical letters” of the ecclesiastical
calendar, times and other details of eclipses, together with methods
for finding the places of planets, and for casting horoscopes. This
is the Alfonso who was so much shocked at the complexity of Ptolemy’s
multitudinous circles that “the ointment of his name is marred,” says
Fuller, “with the dead fly of his atheisticall speech”: “If only the
Creator had consulted me, when He made the world, I would have given
some good advice!”

[Sidenote: Sylvester II. (Gerbert) Pope, 999-1003.]

Not one of all these books pretended to add any new discovery
to astronomy: all intellectual energy was absorbed in eagerly
assimilating the knowledge stored by Greeks and Arabs. Nor were any
great observatories founded in Europe yet, in imitation of Alexandria,
Rhodes, or Baghdad. The instruments in use were celestial globes and
small portable astrolabes and quadrants for determining positions
and angular distances between the heavenly bodies. The learned pope,
Sylvester II., who had studied astronomy among the Moors in Spain, was
so skilful in making astrolabes that some accused him of gaining the
art by selling his soul to the devil!

[Sidenote: Albertus Magnus 1193-1280.]

[Sidenote: Aquinas 1225-1274.]

When Aristotle first came to Paris (about 1200 A.D.), in Oriental
dress, and accompanied by Moslem authors, the Council of Paris
denounced him as an infidel; yet in less than fifty years all his works
were placed on the list of books prescribed in the university course.
This was brought about by the Dominicans. In six of his twenty-one
ponderous volumes the German friar Albertus Magnus paraphrased the
whole of Aristotle’s works, and stripping his philosophy of the
pantheistic and materialistic garb in which the Spanish Arab Averroës
had clothed it, presented the Greek philosopher as an ally of
Christianity. The Italian saint, Thomas Aquinas, pupil of Albertus,
in his much more readable commentaries and treatises, popularized
this idea so successfully that Aristotle—_the_ Philosopher, as he was
called—speedily became as great an authority on every other subject as
he had always been on logic.

It was a mutual victory. Aquinas captured the Greek for the Christian
faith; Aristotle won the western world to accept his theories. No
longer was the doctrine of a spherical Earth called “an old heathen
theory”: it was almost an integral part of the Catholic faith.
Aristotle’s demonstration that there must be a First Mover, himself
unmoved, became an argument for the existence of the Christian Deity;
the intelligences which preside over the celestial movements were
interpreted as the nine hierarchies of angels whose existence was
taught by the Church. To the eight spheres of the Greeks and the
Primum Mobile of the Arabs, the thirteenth-century Christians added
the all-embracing heaven of heavens, the Empyrean, to be the abode of
the Creator and blessed spirits. Within the central immoveable earth
they placed Purgatory and the fires of Hell. They accepted the limits
of the habitable earth as laid down by Ptolemy, but kept Jerusalem as
the centre by asserting that it was situated 90° from the Pillars of
Hercules, and 90° from the mouths of the Ganges. Eden, the earthly
paradise of Adam and Eve, was represented on contemporary maps as in
the extreme East, separated by sea from the eastern boundary of the
inhabited earth.

Thus theology and science supported one another. All learning was
sacred, and all that man’s mind is capable of understanding he might
aspire to know, for the search if rightly pursued would lead at last
to the perfect bliss of beholding with unveiled eyes the Source of all
Truth.




_SECOND PART._

THE ASTRONOMY OF DANTE.


I. POPULAR ASTRONOMY IN ITALY IN DANTE’S TIME.

In the first part of this book we have sketched the story of man’s
thoughts about the stars, from primitive days until the thirteenth
century of our era. We have seen what a wealth of imagination and
invention the Greeks brought to bear on the purely empirical science of
Egypt and Babylon and Homeric Greece, and how out of all the systems
devised by them between 600 B.C. and 100 B.C. one survived, which
was completed and expounded by Ptolemy in the second century after
Christ in his great _Syntax_ or _Almagest_. Its fundamental principles
were that Earth is a sphere, at rest in the centre of the Universe,
surrounded on all sides by spherical heavens, and that the movements
of all the heavenly bodies are explained by a combination of uniform
circular movements.

In the succeeding centuries there were few who could appreciate his
work, and during the Dark Ages it was scarcely known in Europe, but
was preserved by Nestorian Christians in schools and monasteries of
Persia, whence it was unearthed by Mahomedan princes, five centuries
after Ptolemy’s death; and when another five centuries had passed it
was brought back to Europe, tinged with Oriental thought, and almost
immediately became immensely popular among scholars.

Then there arose one of the world’s greatest poets, and, a thousand
years after Ptolemy’s death, immortalized his work, writing in a tongue
unknown to Ptolemy, and for nations which in his day were only just
struggling into existence. As Homer reflects to us man’s primitive
conceptions of the Universe, so Dante reflects the ideas of Ptolemy and
his school.

And because he lived just at this time he was able to write with
perfect confidence, quoting Ptolemy and the Catholic Faith side by
side as infallible authorities in astronomy. Had he lived in the early
Christian centuries he would have been obliged to choose between
classical and orthodox views; had he been born three centuries later,
he would have found Copernicus and Galileo ranged against Ptolemy and
the Church. Even Milton writing a hundred years after the death of
Copernicus, could not make up his mind which system to adopt, and the
astronomy of _Paradise Lost_ is a curious jumble of ancient, modern,
and transitional ideas. He describes the Primum Mobile as a “firm
opacous globe”[71] on which Satan alights and walks about, yet later on
tells us that we need not believe in its existence if Earth is turning
on her axis;[72] the archangel Raphæl describes to Adam the Creation,
at which he was present, yet declares that he himself does not know
whether the sun circles round Earth, or Earth round the sun. This the
great Architect had wisely concealed from man and angel,

------------------------------------------------------------------------
[71] _Paradise Lost_, II. 418.

[72] _Paradise Lost_, VIII. 34-38.

                         “perhaps to move
    His laughter at their quaint opinions wide,
    Hereafter when they come to model heaven,
    And calculate the stars, how they will wield
    The mighty frame, how build, unbuild, contrive,
    To save appearances; how gird the sphere
    With centric and eccentric scribbled o’er,
    Cycle and epicycle, orb in orb.”[73]

[73] _Paradise Lost_, VIII. 77-84.
------------------------------------------------------------------------

Such inconsistencies are not found in Dante’s work, and nothing could
have been further from his thoughts than to imagine the Creator mocking
at man’s mistakes and ignorance. Like the angelic doctor, Thomas
Aquinas, he considered man’s desire for knowledge as one of his highest
attributes, and believed that it had been given to him in order to be
satisfied.

But before we examine Dante’s writings, it will be interesting to form
an idea of the spirit in which astronomy was generally regarded by his
fellow-countrymen, and what were his opportunities of studying it.

Dante Alighieri was born in Florence in or about the year 1265, and
died in 1321. There can be no doubt that the part of star-lore which
appealed most to the general public in Italy at this time, educated and
ignorant alike, was the art of the astrologers. The movements of the
heavenly bodies were regarded not merely as omens, but as the actual
instruments by which every event on Earth was brought to pass. Every
class of plants, every race of animals, was thought to be under the
protection of some planet or constellation; so if it was a bad year for
certain fruits, or if an epidemic broke out among the cattle, this was
because the guardian planet was unfavourably placed, or an evil planet
was in the protecting constellation. Floods and drought, prosperity and
death, properties of minerals such as the lodestone’s attraction for
iron or the emerald’s alleged power of blinding serpents, the instincts
of animals and the impulses of men, all were subject to the influences
of the stars; and naturally the men who understood and interpreted
their movements were held in great repute.

Some of them were unscrupulous quacks, like the one-eyed prophet of
Brescia, mentioned by the gossiping friar Salimbene.[74] He “called
himself an astrologer and diviner,” and received daily “ten great
pennies of silver, and nightly three great Genoese candles of the
purest wax” from a political party in Modena, as a recompense for
advising them how to act. On one occasion he prophesied a victory for
them, but he had little faith in his own words, for being threatened
with violence if his prophecy should fail, he “carried off all that
he had gained and went his way without saluting his hosts.” “Then,”
adds the friar, “the men of Sassuolo began to mock them, as men who
sacrifice to devils and not to God, as it is written in Deuteronomy.”

------------------------------------------------------------------------
[74] All quotations from Salimbene’s Chronicle are taken from Coulton’s
_From Saint Francis to Dante_.
------------------------------------------------------------------------

But most of these men, like Asdente of Parma, sincerely believed in
their own ability to foretell events, and they usually combined some
other favourite forms of soothsaying, as well as a little alchemy,
with astrology. Asdente is described by Salimbene as “a poor working
cobbler, pure and simple, and fearing God, and courteous and urbane;
illiterate, but with great illumination of mind.” His proper name
was Master Benvenuto, but he was “commonly called Asdente, that is,
toothless, by way of contrary, for he hath great and disordered teeth
and an impediment in his speech, yet he understands and is understood
well. He dwells at the bridge-head of Parma, hard by the city moat
and the well, along the street which goes to Borgo San Donnino.” This
humble prophet was said by Dante to be the best known citizen of all
Parma (_Conv._, IV. xvi. 65-71): he was asked to dinner by a bishop,
and consulted by the warring factions of Reggio and Parma. He was said
to have foretold the death of two popes, and a naval defeat of Pisa by
Genoa.

The greatest generals of the day governed their tactics by the advice
of astrologers who regularly accompanied them to the field and the
camp. The famous Ghibelline, Guido of Montefeltro, who is called
by Villani the cleverest soldier of his times[75] retained Guido
Bonatti[76] in his service and was believed to have gained his great
victory at Forli (in 1282) through the advice of this astrologer.
Bonatti is diversely described as a tiler and a lawyer, but whatever
his original occupation may have been he found that the position of
private astrologer brought him both more fame and more money. He wrote
a book on Judicial Astronomy, and Vincent de Beauvais describes him as
celebrated throughout the western world for his knowledge of the art.

------------------------------------------------------------------------
[75] _Croniche Fiorentine_, Bk. VII. par. 80.

[76] _Inf._ xx. 118.
------------------------------------------------------------------------

But Bonatti’s fame was faint and fugitive compared with that of the
wizard Michael Scot. He is one of the picturesque figures of the
thirteenth century, round whom so many legends have gathered that the
facts of his life are difficult to glean. It seems that he was born
in Fifeshire of a noble Scottish family, at the end of the twelfth or
beginning of the thirteenth century, that he studied in Oxford and
Paris, and then spent some time in Toledo. Here he learned Arabic,
and probably also astrology, for it was so commonly practised there,
especially among the Arabs and the Jews, that it was sometimes called
the Toletan art. Afterwards he went to Germany, and was discovered by
Frederick II., who took him to Italy. His great learning earned the
admiration of Pope Gregory IX., who speaks of him quite affectionately
in a letter to the Archbishop of Canterbury; and it is said that
Honorius II. would have liked to make him an archbishop. But Sir
Michael the Scot found Frederick’s court more congenial. The Emperor,
who was himself a poet, was a munificent patron of literature and art,
and attracted to himself men of talent from all parts of the world. The
culture of both East and West met at that brilliant Sicilian court[77]
which was his for fifteen years before the title of Emperor was added
to that of King of Naples and Sicily. Indeed it was his “fellowship
with Saracens”[78] which was one great reason for the accusation of
heresy on account of which Dante placed him among the Epicureans in the
_Inferno_. He knew Arabic, as well as French, German, Italian, Latin,
and Greek. Michael Scot’s acquaintance with Moorish literature and
language was a bond of sympathy between them; he became astrologer to
Frederick, and at the Emperor’s wish he superintended a new translation
of Aristotle’s works from Arabic into Latin. His taste for astronomy is
evidenced by the fact that out of these he chose to translate the _De
Cœlo_ himself.

------------------------------------------------------------------------
[77] _V. E._, I. xii. 20-35.

[78] Villani, _Croniche Fiorentine_, VI. 1 and 24.
------------------------------------------------------------------------

An absurd story is told by Salimbene about Frederick and Michael
Scot, which, however, shows what was believed of his capabilities as
an astronomer. The Emperor one day asked him, when they were in the
palace together, how far they were from the sky, and the astrologer
told him the distance. They then took a long journey together, during
which the palace was secretly lowered, and on their return Frederick
asked casually whether the sky could really be so distant as Michael
had said. “Whereupon he made his calculations, and made answer that
certainly either the sky had been raised or the earth lowered; and then
the Emperor knew that he spake truth.”

Michael Scot is said to have warned Frederick that he would die in
Florence, for which reason the Emperor would not enter that city;
but having thoughtlessly gone to a town called Florentiola he died
there; “for this,” adds the historian, “is almost always the way, the
devil tricks one by a play upon words.” It is curious to contrast
this remark, attributing Michael’s prophecy to the evil powers, with
Salimbene’s quotation from him, in exactly the same spirit as if he
were quoting from an Old Testament prophet:—“that the word of Michael
Scot may be fulfilled in them, which he wrote in his verses wherein he
predicted the future, ‘And the factions at Reggio shall hold ill words
together.’” The same author brackets him with others who have foretold
the future, in a list which reads curiously to us—“Abbot Joachim,
Merlin, Methodius and the Sybil, Isaiah, Jeremiah, Hosea, Daniel, and
the Apocalypse, and Michael Scot who was astrologer to the deposed
Emperor Frederick II.”

Besides these prophetic verses, Michael wrote several books which treat
almost exclusively of astrology, alchemy, and other occult “sciences,”
and even in the fifteenth century it was said that his magic books
could not be opened without danger, because of the fiends who were
thereby invoked! He seems to have returned to his native Scotland to
die, but the date is very uncertain. We do not know whether Dante’s
picture of him is drawn from memory, or hearsay of some who had seen
the lanky Scotsman among the southerners, by nature taller and thinner
than they, and worn by his prolonged studies.

    “Quell’ altro che ne’ fianchi è così poco
    Michele Scotto fu, che veramente
    Delle magiche frode seppe il gioco.”[79]
                                (_Inf._ xx. 115-117).

------------------------------------------------------------------------
[79]
    “That other, round the loins
    So slender of his shape, was Michael Scot,
    Practised in every sleight of magic wile.”
                                            _Carey._
------------------------------------------------------------------------

It was perhaps the winning personality or the prudence of the canny
Scot which enabled him to bring a brilliant career to a peaceful close,
favoured by the Church as well as by the excommunicated Emperor,
although his studies were of so dubious a nature, and he was intimate
with heretic Mahomedans and Jews. Cecco d’Ascoli was not so fortunate.
This learned Italian received the high and honoured post of professor
of astrology in Bologna, where he lectured and cast horoscopes for his
students. He was well versed in natural science, but the shady side of
astrology had a fatal attraction for him: he fell under suspicion as a
sorcerer, was condemned, and burned at the stake in Florence in 1327
(six years after Dante’s death).

The reputations achieved by these and other thirteenth-century
astrologers in Italy, belonging to such different ranks of life, show
what an immense importance was attached to their art by the general
public. Yet we shall be greatly mistaken if we think that it was only
to acquire skill in this fascinating pursuit that men thronged to hear
Cecco lecture, or pored over Latin manuscripts. The intense ardour for
knowledge which marks this period made them eager to understand the
world around them and the sky above their heads.

[Illustration: ASTRONOMY.

_From a fresco in the Spanish Chapel of Santa Maria Novella, Florence._

[_To face p. 217._}]

It would be a shame, writes one, to live in a house and not know how
it is built or what shape it has, never to examine the walls, and
floors, and ceilings, nor to consider the use of the wooden beams used
in its construction. In like manner we should not be content without
understanding the form and structure of the Universe in which we live.
Man, with his upright attitude and his head held high, unlike the
animals, was designed by his Creator to look and listen, to know and
comprehend this marvellous Universe, and especially that noblest part
of it above him, the heavens and their wonderful movements. For thus
alone can he learn to know God Himself, the great Architect of the
World.

In writing thus, Ristoro, the monk of Arezzo, was not only echoing
the thoughts of Plato and Cicero, he was expressing the feeling for
astronomy as a noble and elevating study which was general among
thoughtful men of his time. It was expressed also in contemporary art.
Visitors to the “Spanish Chapel” in the cloisters of a Florentine
church will remember seeing on the frescoed walls the figure of
Astronomy as she was personified in Tuscany in the fourteenth century.
She sits among her peers, the sciences of the Trivium and Quadrivium,
the only one who wears a crown; her fair hair frames a spiritual face,
one hand is lifted heavenwards, the other holds a celestial sphere, on
which the broad band of the zodiac crosses the “equator of the day.” At
her feet sits a kingly figure in flowing robes, also crowned, and with
a face of singular beauty and refinement; he gazes up into the skies
with a rapt expression, and on his knee is a book in which he writes
what he sees.

This nameless figure was identified doubtfully by Ruskin as Zoroaster,
who was considered by many as the inventor of astrology, but surely
it can be no other than Ptolemy with his _Almagest_. For Ptolemy, the
prince of astronomers, was often and naturally confused with the royal
race who had patronized astronomy at Alexandria; as for instance by
Omons, a thirteenth-century writer, who says in his _Image du Monde_
that “Ptolemy king of Egypt” wrote the _Almagest_. The curious mode
of dressing the hair and beard may have been thought by the artist to
represent an ancient Egyptian fashion.

Ptolemy, we know, was universely acknowledged at the time to be “Master
of Astronomy,” as Brunetto Latini calls him. His _Almagest_ was only
known indirectly, but it was believed to contain all that could be
known about the movements and the nature of the heavens. Some minor
additions and corrections had been made, as we have seen, by the Arab
astronomers, but the system was accepted as a complete and satisfactory
explanation of all celestial phenomena. Hence no professional
astronomer was expected to make discoveries; he was simply well versed
in the work of those who went before him, skilful in the use of a few
simple instruments and tables, and practised in applying the principles
of astrology.

A general notion of the Ptolemaic system was widely diffused. For
those who could not read Latin there were encyclopædic works written
in the vernacular and in a popular style, such as the _Trésor_ of
Brunetto Latini, and these always contained a section on astronomy.
The average educated man probably had only vague ideas about epicycles
and eccentrics, and perhaps had never heard of the Arab estimates of
the sizes of the planets; but he would know that astronomy taught
that Earth is a globe, motionless at the centre of the universe, and
smaller than any of the stars; he would know the names of the seven
planets (including among these the sun and moon), and probably also
their colours, their periods, and their astrological significance; the
zodiacal constellations would be familiar, especially as they were
often used decoratively; and he would believe that stars and planets
are set in crystalline transparent spheres.

Moreover, he would often be more of an astronomer than he knew, for he
would learn almost unconsciously many things of which modern men are
ignorant. The ill-lighted streets and the dangers of night journeys
would force him to be better acquainted with the motions and phases
of the moon than most of us are to-day; he would know when and where
to look for different stars; and the want of a watch would make it
necessary for him to be able to take his time from the sun at any
season of the year. He could, however, sometimes consult a sundial on
a church wall or in a private garden, and the church chimes rang out
at tierce, and nones, and vespers. These were heard at intervals which
were much longer in summer than in winter, for the system of “temporary
hours” was used by the Church, and the service of tierce was held
halfway between sunrise and noon (or nones), and vespers was halfway
between noon and sunset.


_II. DANTE’S STUDIES._

DANTE’S STUDIES.

Dante was far above the level of the average educated man. Not that
his scientific ideas were in advance of his age: on the contrary, one
special interest that they have for us is that they illustrate, like
his political and religious views, the beliefs and feelings of the
period. His authorities were the authorities of all, but he had studied
them and made their thoughts his own, as few others did, except some
churchmen and professed scholars. The extent and depth of his reading
is evident from his own writings, and his great learning is noted with
admiration by all his biographers. Giovanni Villani, in the earliest
account we possess of Dante, says that he was “a great scholar in
almost every branch of learning, although he was a layman.” Boccaccio
would have us believe that while still a child, so young that he might
be expected to spend his time playing with other children or sitting
on his mother’s knee, he gave the whole of his time to reading and
learning. Lionardo Bruni, however, assures us that though he was an
ardent student, and showed unusual powers at an early age, he by no
means tried to “sever himself from the world, but living and moving
about amongst other young men of his age, he approved himself gracious
and skilful in every youthful exercise.” It was wonderful, he says, how
Dante maintained all his social and civic intercourse while he pursued
his studies so fervently.

In truth, the poet’s troubled life was far removed from that life of
calm retirement which one thinks suitable for a scholar. In his early
youth he experienced a passionate love and sorrow; a year before the
death of Beatrice he was fighting for Florence in the great battle of
Campaldino, nor was it the first time he had borne arms; in 1296 he
spoke in the council of the Hundred; in 1300 he was ambassador for the
Tuscan League to San Gemignano, and was elected to the highest office
a citizen could hold in his native city, that of Prior; in 1301 he
was ambassador to the Pope in Rome, and in the year following he was
exiled. After this he was always wandering, often in great poverty,
dependent on first one patron and then another, always hoping that some
turn of affairs would restore him to Florence, always taking a keen and
active interest in Italian politics, until he died, still in exile, at
Ravenna. Add to this the difficulties common to all scholars of his
day, viz. absence of printed books, public libraries, and journals,
etc., and we must marvel how he ever found the opportunities and the
serenity of mind for his prolonged studies.

Boccaccio adds another obstacle—his wife! To console him for the death
of Beatrice, his friends and relatives persuaded him to marry a wife of
their choosing with melancholy results:—

    “Dante formerly had been used to spend his time
    over his precious studies whenever he was inclined,
    and would converse with kings and princes, dispute
    with philosophers, and frequent the company of
    poets.... Now, whenever it pleased his new mistress
    he must at her bidding quit this distinguished
    company, and bear with the talk of women, and to
    avoid a worse vexation must not only assent to
    their opinions, but against his inclination must
    even approve them. He who, whenever the presence of
    the vulgar herd annoyed him, had been accustomed
    to retire to some solitary spot, and there to
    speculate on the motions of the heavens, or the
    source of animal life, or the beginnings of created
    things, or may be to indulge some strange fancy, or
    to compose somewhat which after his death should
    make his name live into future ages, he now, as
    often as the whim took his new mistress, must
    abandon all such sweet contemplation, and go in
    company with those who had little mind for such
    things.”[80]

------------------------------------------------------------------------
[80] Boccaccio’s _Vita di Dante_; Translation from Toynbee’s _Dante
Alighieri_ (Oxford Biographies), pp. 92, 93.
------------------------------------------------------------------------

However, after a long tirade against wives, Boccaccio owns that as far
as concerns Dante the picture is entirely imaginary. He believes the
marriage was an unhappy one, because after his exile Dante and his
wife never met again, but we have no evidence whatever that while they
were together their life was as Boccaccio depicts it. Doubtless family
life and the care of four children interfered to some extent with
Dante’s studies, but the one detail Boccaccio affirms as fact among his
fancies, namely that the poet refused for nineteen years to see his
wife, seems rather to imply that one thing poor Gemma did know how to
do was to leave her husband in peace when he did not desire her company.

When and where Dante began to study astronomy seriously it is not easy
to say. His favourite study in his youth was poetry, but his parents
(says Bruni) gave him a good general education, engaging such teachers
as could be found in Florence, where as yet there was no university.
But seeing how clever the boy was, his relatives and friends helped and
encouraged him, and among the latter Bruni mentions Brunetto Latini.

This famous Florentine was a very learned lawyer, who during Dante’s
infancy and boyhood held high offices of state in the city. It is not
possible, therefore, that he should have had pupils at this time, and
he cannot have been Dante’s master in any strict sense of the word, as
Vasari affirms, and as many commentators have assumed on the strength
of the moving interview between these two in the _Inferno_.[81]
Dante’s affectionate greeting mingled with reverence, and the fatherly
solicitude of Brunetto, suggest just such a connection as Bruni
indicates. The elderly man had taken an interest in the budding genius
of the boy, and had held inspiring conversations with him from time
to time on serious subjects, and by his own example had encouraged
the youth to win fame through his pen. For Dante was no doubt well
acquainted with Brunetto’s _Tesoretto_, and his more ambitious and
voluminous _Trésor_, which Brunetto specially commends to his care.[82]
This was a compendium of knowledge, a small part of which was devoted
to the elements of astronomy, and it may well be that this short
epitome was Dante’s first introduction to the science.

------------------------------------------------------------------------
[81] _Inf._ xv. 23 _et seq._

[82] _Inf._ xv. 119.
------------------------------------------------------------------------

Some have thought that Brunetto’s advice to Dante to follow his star
“Se tu segui tua stella ...,”[83] indicates that he had cast the poet’s
horoscope; but there is no evidence that Brunetto had ever practised
astrology, or even that he took special interest in it above other
branches of learning.

------------------------------------------------------------------------
[83] “If thou follow thy star,” _Inf._ xv. 55.
------------------------------------------------------------------------

Villani and other biographers tell us that after his banishment from
Florence, therefore in middle age, Dante went to the University at
Bologna, but they seem to have made this statement rather because of
its probability than because they knew it for fact. It is, however,
quite possible that he spent a couple of years there, between 1304
and 1306. He probably left his “primo rifugio”[84] at Verona when
Bartolommeo della Scala[85] died in March 1304, and we know nothing of
his whereabouts till August 1306, when he was in Padua, as is proved by
a fifteenth century document.[86] Now in 1306 a number of Ghibelline
students and professors left Bologna for Padua; and we know that Dante
had friends among the Bolognese professors, for later on he seems to
have corresponded with Cecco d’ Ascoli,[87] and Del Virgilio entreated
him to come and receive the laurel crown, an invitation which the poet
refused in one of his Latin Eclogues. Bologna and the Bolognese are
referred to several times in Dante’s works, and the friar Catalano is
no doubt alluding to the school of theology at the University when he
says in _Inf._ xxiii. 142-144 that he used to hear at Bologna much
about the wickedness and the lies of the Devil. One vivid passage can
hardly be anything but a personal reminiscence of the Carisenda, the
leaning tower at Bologna. The poet compares his fear when he saw the
giant Antæus stooping over Virgil and himself to the sensation of
looking up at the Carisenda from beneath the leaning side, when a cloud
is passing over it, and the spectator feels that the tower is about to
fall upon him.[88] (The tower was much higher in Dante’s day than it
is now, part having been pulled down in the middle of the fourteenth
century).

------------------------------------------------------------------------
[84] “First refuge,” _Par._ xvii. 70.

[85] _Par._ xvii. 71, 72.

[86] Imbriani, _Dante a Padova_.

[87] “_Torno a Ravenna e de lì non mi parto_ (I am going back to
Ravenna, and shall not leave it again), is a line in the _Acerba_ which
Cecco d’ Ascoli puts into the mouth of Dante, as though from a letter
written to himself from the divine poet at the time” (about the year
1319). _Dante and Giovanni del Virgilio_, by Wicksteed and Gardner, p.
84.

[88] _Inf._ xxxi. 136-141.
------------------------------------------------------------------------

The University at Padua was also famous, and as it was originally an
offshoot from Bologna and modelled on the same plan, it is sure to
have included astronomy in its curriculum. But Dante does not seem to
have stayed here more than a few months.

There is also a tradition that he went to Paris, the greatest
intellectual centre of his times, and that he himself heard those
lectures of Sigieri, the philosopher, in the Street of Straw, of
which he makes mention in _Par._ x. 137. This is possible, but quite
uncertain; the allusion to Sigieri is no proof, since it has lately
been discovered that he died in Italy, and his story was well known
there.

After sifting all the evidence available, we can only echo Boccaccio,
and say of Dante that “As it was at divers ages that he studied and
learned the divers sciences, so likewise it was at divers places of
study that he mastered them under divers teachers.”


_III. BOOKS ON ASTRONOMY USED BY DANTE._

BOOKS ON ASTRONOMY USED BY DANTE.

We shall probably be right if we conclude that Dante’s knowledge of
astronomy was principally gained from independent reading, and from
conversation and discussion with learned men. Like a true scholar,
he was learning all his life, for in the _Paradiso_ he corrects the
opinion expressed earlier in the _Convivio_ about the origin of the
markings in the moon.

Boccaccio’s description of his planning out a course of study and
attacking some subjects alone in his youth agrees with his own
account of his lonely struggles with Latin authors;[89] and it is
quite credible that he suffered heat and cold, and went without food
and sleep in his eagerness to learn, since he himself mentions quite
casually that at one time he injured his sight by constant reading, so
that the stars appeared blurred to him, until by rest and bathing with
cold water it became strong again.[90]

------------------------------------------------------------------------
[89] _Conv._ II. xiii. 22-26.

[90] _Conv._ III. ix. 146-157.
------------------------------------------------------------------------

His diligence must have been great, and his memory wonderful, judging
from the numerous quotations from classical and contemporary authors
to be found in his writings. They seem to be chiefly from memory,
and it is not likely that he can often have had many books by him
when writing. If he gives a reference it is often a vague one, and
occasionally wrong: his authorities on astronomical questions are
sometimes “the mathematicians,” “the astrologers,” or “the sages of
Egypt,” by whom he means the Alexandrian astronomers.

One does not, of course, expect mediæval writers to verify their
references, or to have our modern scruples about quoting other authors
without acknowledgement: in those days they were only too glad to get
their information wherever they could, often at second or third hand,
and to make it their own by storing it in their memories. Nevertheless,
from a careful study of Dante’s direct quotations, and his allusions
and reminiscences, which are sometimes unconscious, a good idea may be
gained of his range of reading, and of the books and authors on whom he
chiefly relied for his astronomical data.

His supreme authority was of course Ptolemy. But it would only be by a
rare chance that he could see the _Almagest_, even in a translation,
and all the evidence that we can find in his own writings points to
its being entirely unknown to him. On each of the three occasions that
he quotes Ptolemy’s opinion on subjects dealt with in the _Almagest_
he is wrong: once it is Ptolemy’s view on the physical nature of
the Galaxy,[91] as to which none had been expressed, although its
appearance was carefully described; in another case he implies that
Ptolemy discovered precession, and says that he added a ninth heaven
to account for it,[92] and this double mistake was apparently copied
from Albertus Magnus or Averroës.[93] As we know, it was Hipparchus
who discovered precession, and Ptolemy gives him the credit for in the
_Almagest_; it was the Arabian astronomers who added the ninth sphere.

------------------------------------------------------------------------
[91] _Conv._ II. xv. 73-77.

[92] _Conv._ II. iii. 36-52, _V. N._ xxx.

[93] Averroës, in his commentary on Aristotle’s _De Cœlo_, says
that the ancients believed the eighth, or starry, heaven, to be the
outermost, but that Ptolemy assumed a ninth, “because he said that he
had discovered a slow motion along the signs of the zodiac in the fixed
stars.” Albertus Magnus, in his _De Cœlo et Mundo_, Book II., says also
that the ancients, including Aristotle, believed that there were only
eight heavens, but that Ptolemy, so far as he can understand, believed
in ten, on philosophical not mathematical grounds (compare _Conv._
II. iii. 40, 41). Albertus accepted the theory of “trepidation,” and
thought this was the only movement which ought to be assigned to the
star sphere; there remained, therefore, two motions, which affect all
the planetary spheres and the star sphere, for which two more spheres
must be assumed, a ninth sphere for precession, and a tenth, the primum
mobile, for the diurnal motion. Outside all was the Empyrean. Dante
never mentions trepidation, and evidently did not believe in it: he
needed only nine moving spheres, therefore, but counts the Empyrean as
a tenth heaven.
------------------------------------------------------------------------

On the other hand Dante quotes twice quite correctly from the
_Tetrabiblios_, which was more widely known.[94] He may, therefore,
possibly have read it, and he alludes to it in the _Convivio_, though
by a curious slip he does not give its name, thinking he has done so
already: “Tolommeo dice nello allegato libro....”[95] This is in the
fourteenth chapter of the second treatise, but so far from having just
quoted any special work by Ptolemy he has said nothing at all about
him since the third chapter, and then it was only his opinion and name
that were mentioned. I have not been able to trace the quotation given
in the _Quæstio de Aqua et Terra_ (xxi. 29-31), where Ptolemy is said
to have asserted that things on earth resemble things in heaven, but
this probably comes also (or was supposed to come), from the “judicial
astronomy” of the _Tetrabiblios_. It is not taken from the _Almagest_.

------------------------------------------------------------------------
[94] _Conv._ II. xiv. 198-202. _Ibid._ 249-253.

[95] “Ptolemy says in the book above cited.”
------------------------------------------------------------------------

The elements of Ptolemy’s system, however, could be learned indirectly,
and it seems that Dante had recourse to the excellent epitome of the
Arab astronomer Alfraganus. It is true that his name is only mentioned
once, and his book once; but nearly all Dante’s astronomical data
appear to have been taken from him, and his very expressions are
sometimes repeated.

One of the most striking examples of borrowing from the _Elementa
Astronomica_ of Alfraganus occurs in the _Paradiso_, where Dante likens
twenty-four spirits to as many brilliant stars.[96] He makes up the
number by taking fifteen specially bright stars from different parts
of the sky, and adding to them the stars of Ursa Major and two stars
of Ursa Minor. The seven chief stars of Ursa Major are well known,
but Beta and Gamma Ursæ Minoris are not conspicuous nor specially
familiar; and why, if he takes fifteen unnamed, should he name any of
the twenty-four? Turning to chapter 19 of Alfraganus’ book, we find
that he follows Ptolemy in enumerating fifteen first-magnitude stars in
different parts of the sky, and then he gives as examples of the second
magnitude (_i.e._ next in brightness) Benet Naax and Alfarcatein, Arab
constellations which correspond with the tail of Ursa Major, and Beta
and Gamma of Ursa Minor.

------------------------------------------------------------------------
[96] _Par._ xiii. 1-13.
------------------------------------------------------------------------

There is no reason to suppose that Dante knew Arabic, but there were
several versions of Alfraganus in Latin, and it is even possible to
determine with some certainty which of them he used. Speaking of
the movements of the planet Venus, he says that they may be found,
summarized from the best demonstrations of the astrologers, in the
_Book of the Collection of the Stars_:—

    “Li quali, secondochè nel _Libro dell’ Aggregazione
    delle Stelle_ epilogato si trova, dalla migliore dimostrazione
    degli astrologi ....”
        (_Conv._ II. vi. 133-136).

Although the usual name for the book of Alfraganus in Latin was
_Elementa Astronomica_, the version for which mediæval students
were indebted to the indefatigable translator Gerard of Cremona
bears in the MSS. the title _Alfragani liber de aggregationibus
Scientiæ Stellarum et de principiis cœlestium motuum_. It is this
book, therefore, that Dante means, though he has translated the title
somewhat inaccurately.[97]

------------------------------------------------------------------------
[97] See Schiaparelli’s letter in Lubin’s _Dante e gli Astronomi
Italiani_. The name is, however, also used as a sub-title in the
printed edition of Christmann, Frankfort, 1590, which was based not
on the translation of Gerard but of Johannes Hispalensis of Seville;
and Toynbee thinks that this Frankfort edition represents most nearly
the version of Alfraganus used by Dante. It is the only one of the
five printed editions which gives the same figure for the diameter of
Mercury as that quoted by Dante. See Toynbee, “Dante’s Obligations to
Alfraganus” in _Romania_ xxiv. 95, and Moore, _Studies in Dante_ iii.
p. 3, _note_.
------------------------------------------------------------------------

There were several other books known to Dante from which he must have
gleaned information about Ptolemy’s system, but Alfraganus we may
regard as his standard reference book. Many versions of Alfraganus are
still extant, and it is pleasant to feel that we can hold in our own
hands Dante’s text-book on astronomy. The best known is the printed
edition of Golius, published in Amsterdam in 1669: it is in both Latin
and Arabic, and opening in the middle we may turn the pages backwards
to see the beautiful Arabic letters of Alfraganus’ own language, which
is written from right to left, or forwards to look at the Latin in
which he became known to Dante.

Next in importance to Alfraganus among Dante’s authorities on astronomy
was Aristotle. We have seen how overwhelming his authority became in
natural science in the second half of the thirteenth century, and how
for some time scholars failed to distinguish between the system of
spheres devised by Eudoxus, which was the scheme upheld by Aristotle,
and the epicycles and eccentrics of Ptolemy. Among all Aristotle’s
admirers none was more devoted than Dante: for him Aristotle is not
only “Il Filosofo,” the Philosopher _par excellence_, as he was
generally called in that age; he is “quello glorioso filosofo al
quale la Natura più aperse li suoi segreti,” his intellect was “quasi
divino,” and his words are of “somma e altissima autoritade.”[98]
Throughout Dante’s own writings his references to Aristotle are so
frequent that Dr. Moore observes: “The amount and variety of Dante’s
knowledge of the contents of the various works of Aristotle is nothing
less than astonishing.”[99]

------------------------------------------------------------------------
[98] “That glorious philosopher to whom Nature most fully revealed her
secrets,” _Conv._ III. v. 54-56; “almost divine,” _Conv._ IV. vi. 133;
“supreme and highest authority,” _Ibid._ 52.

[99] Moore, _Studies in Dante_ I. (Scripture and Classical Authors in
Dante), from which much of the information in this chapter has been
taken.
------------------------------------------------------------------------

He does not, however, consider Aristotle infallible as regards the
details of astronomy, for in these the philosopher was only following
the observers and mathematicians;[100] but in all matters which depend
upon first principles, in which Dante would include the form of the
earth, Aristotle’s authority may not be called in question.[101] In
cosmical physics, such as the doctrine of the four elements, and in
meteorology, Dante follows “il mio Maestro”[102] implicitly, and it is
also largely from the _De Cælo_ that he gained his knowledge of early
Greek speculations regarding the universe.

------------------------------------------------------------------------
[100] _Conv._ II. iii. 19-21.

[101] _Conv._ III. v. 62-65.

[102] “My master.”
------------------------------------------------------------------------

Dante knew little more of Greek than of Arabic. His occasional use of
Greek words is enough to prove this—for example when he discusses the
Pythagorean theory of “Antictona,” using the accusative as if it were a
nominative.[103] In several passages he implies that the language was
not known to him, and he distinctly states that he used translations of
Aristotle’s works. Here again we are able to identify the versions he
used. In _Conv._ II. xv. 59-73 he complains that it is impossible to
know what Aristotle believed about the Milky Way, because in the “old
translation” he is made to say one thing, and in the “new translation”
quite another. From his quotations of these two conflicting opinions,
we are able to deduce that the “old translation” was that which Michael
Scot made from the Arabic, and the “new translation” that of Aquinas,
which was made direct from the Greek.

------------------------------------------------------------------------
[103] _Conv._ III. v. 32.
------------------------------------------------------------------------

He had access, therefore, to more than one Latin translation of
Aristotle; and beside this, his quotations seem to have been often
taken from commentators and compilers of his own times, especially
Aquinas and Albertus Magnus. This was frequently the case with the
_Meteorologica_ of Aristotle, for the _De Meteoris_ of Albertus Magnus
seems to have been much used by Dante in place of Aristotle’s own work.
Dante quotes it by name as _Meteora_ in _Conv._ II. xiv. 169, and also
in _Conv._ IV. xxiii. 125-126, where he mentions “Alberto” as the
author.

These two, then, the Arab Alfraganus and the Greek Aristotle, were
Dante’s chief authorities in astronomy, both in Latin translations.

Besides these, there is evidence in his writings that he was familiar
with several classical authors who treated of astronomy. He quotes
frequently from many of Cicero’s works, and we find echoes, in two
passages, of the _Dream of Scipio_,[104] which he is almost certain to
have read, since it was a favourite book in his time. There are several
references to Seneca, but the only time that an astronomical phenomenon
recorded by him is mentioned[105] Dante is evidently quoting at
second-hand from Albertus Magnus. With all the works of Virgil, and
with the _Metamorphoses_ of Ovid (from which he took his astronomical
myths)[106] he was evidently very familiar; and Lucan is one of his
authorities for the position of the earth’s equator. In this case the
name of the author and the number of the book are precisely stated.[107]

------------------------------------------------------------------------
[104] _Inf._ ii. 76-78; _Par._ xxii. 134-138.

[105] _Conv._ ii. xiv. 174-176.

[106] Phaëthon, _Conv._ II. xv. 53-55, _Purg._ xxix. 118-120; Latona,
_Purg._ xx. 130-132; the Horses of the Sun, _Conv._ IV. xxiii. 134-139,
etc., etc.

[107] _Conv._ III. v. 115-117.
------------------------------------------------------------------------

Dante had a great reverence for Plato, whom he calls “uomo
eccellentissimo,”[108] and of whom he repeats the mediæval legend that
he was a prince who gave up all for the sake of acquiring wisdom.[109]
Of his writings he only knew the _Timaeus_, probably the Latin
translation and commentary of Chalcidius, which was widely known. Or he
may have been acquainted with Aquinas’ commentary, which has since been
lost. He also knew something of Plato’s teachings through Aristotle and
Cicero, Albertus Magnus, and Aquinas, and perhaps St. Augustine. When
he feels obliged to dissent from the great philosopher’s doctrine that
the souls of men come from the stars, he does so with reluctance and
great gentleness.[110]

------------------------------------------------------------------------
[108] “A man of supreme excellence.” _Conv._ II. v. 21, 22.

[109] _Conv._ III. xiv. 76-79.

[110] _Par._ iv. 22-24, 49-60.
------------------------------------------------------------------------

Among other Greek philosophers who speculated on astronomy, Dante
mentions Thales[111] and Pythagoras. The date when the latter
flourished he takes (he tells us) from Livy, and his theory that the
Universe is governed by the principle of number from Aristotle’s first
book of Metaphysics. The astronomical theories of his school are also
doubtless taken from Aristotle. Dante tells the story of Pythagoras
that he was the first man to be called “philosopher,” because when
asked if he considered himself a wise man, he replied, “No, but only
a lover of wisdom.”[112] Dionysius the Academician and Socrates are
referred to for their opinions on the influence of the stars upon
human souls;[113] and Anaxagoras and Democritus for their galactic
theories,[114] which Dante obtained from Albertus Magnus.

------------------------------------------------------------------------
[111] _Conv._ III. xi. 39; _Inf._ iv. 137.

[112] _Conv._ III. xi. 22-33; II. xiv. 144-147; III. v. 29-44; III. xi.
41-47.

[113] _Conv._ II. xiv. 34, 35.

[114] _Conv._ II. xv. 56.
------------------------------------------------------------------------

Except for Alfraganus, Dante refers but seldom to Arab astronomers.
He does not seem to have known Albategnius. The _De Substantia Orbis_
of Averroës is quoted in the _Quæstio de Aqua et Terra_,[115] and it
is possible that from this book Dante derived a theory about the moon
which he expounds in the _Convivio_. He quotes Alpetragius on circular
existence (dependent on the spheres),[116] Avicenna on the Galaxy, and
again with Algazel on the influence of the spheres,[117] and Albumassar
on meteors.[118] The quotation from the latter, however, is second-hand
from Albertus Magnus, and is a mistake, for the passage is not to be
found in that astronomer’s works. He was born in Turkestan, in 805.

------------------------------------------------------------------------
[115] _Qu._ xviii. 38, 39.

[116] _Conv._ III. ii. 37.

[117] _Conv._ II. xv. 77, II. xiv. 32.

[118] _Conv._ II. xiv. 170-174.
------------------------------------------------------------------------

We may here remind our readers that the three Latin poets, Virgil,
Ovid, and Lucan, were among the world’s five greatest poets met by
Dante in Limbo; that next to Aristotle among the philosophers stood
Socrates and Plato, and near these were Democritus, Anaxagoras, and
Thales, Cicero and Seneca, Ptolemy, Avicenna and Averroës.[119]

------------------------------------------------------------------------
[119] _Inf._ iv. 80, 81, 90, 131-144.
------------------------------------------------------------------------

Among Christian writers, Dante may have gathered some information about
ancient Greek speculations from St. Augustine and Peter Lombard; and
Orosius, the Spanish friend of Augustine, was his chief authority for
that geographical system which, in connection with astronomy, plays
an important part in the time-indications of the _Divina Commedia_.
Orosius had a great reputation among geographers and map-makers.
He had travelled much between Spain, Africa, and Palestine, and he
devotes a chapter to describing the different parts of the earth in his
history _Adversus Paganos_, which he wrote to prove that Christianity
had not injured but benefitted the countries in which it had been
accepted. This fifth century geography seems to have been largely based
on the first-century geography of Strabo, who quotes Eratosthenes,
Posidonius, and Hipparchus among his authorities. Orosius states that
the land is entirely surrounded by Ocean, and is divided into three
continents—Asia, with the mouths of Ganges in the middle of its eastern
coast, Europe stretching vaguely very far to the north-east, and Africa
a narrow and long strip from east to west between the Mediterranean and
the southern ocean. This chapter is quoted in _De Mon._ II. iii. 87-90
and _Qu._ xix. 43; and Orosius is almost certainly “quell’ avocato dei
tempi cristiani,”[120] seen by Dante among the learned doctors in the
Heaven of the Sun.

------------------------------------------------------------------------
[120] “The advocate of the Christian centuries.” (_Par._ x. 199).
Orosius is also mentioned by name in _Conv._ III. xi. 27; _V. E._ II.
vi. 84; and _De Mon._ II. ix. 26.
------------------------------------------------------------------------

The speaker who points him out in these words also mentions his own
name and that of the spirit nearest to him:—

    “Questi che m’è a destro più vicino
     Frate e maestro fummi, ed esso Alberto
     È di Cologna, ed io Thomas d’Aquino.”[121]

------------------------------------------------------------------------
[121]
    “He who is nearest to me on the right
     My brother and master was, and he Albertus
     Is of Cologne, I Thomas of Aquinum.”
                                   (_Par._ x. 97-99).
------------------------------------------------------------------------

These two, so near in heaven, had been close companions on earth. The
youthful Thomas, son of Count d’Aquino in southern Italy, after six
years’ study at the University of Naples joined the Dominican Order,
and went to Cologne to learn from Albert, who was also of noble
family but born in Suabia on the Danube. Together they went to Paris,
together returned to Cologne, but after six more years there their
paths separated: Albert rose to be Bishop of Ratisbon; Aquinas, after
lecturing in Paris, Rome, and Bologna, became a professor at Naples,
and died in Italy in 1274. His master survived him by six years, dying
at Cologne at the advanced age of eighty-seven in 1280.[122]

------------------------------------------------------------------------
[122] Toynbee, _Dante Dictionary_; the source also of many other
details given in this chapter.
------------------------------------------------------------------------

These two are in the foremost rank among authors of his own time who
influenced Dante. He quotes both writers and several of their books by
name,[123] and though he never mentions it he was very familiar with
the _Summa Theologica_ of Aquinas. To the works of these famous authors
he was frequently indebted for astronomical facts, theories, and
history, as already noted. Besides this, his reverence for Aristotle,
his belief in the essential harmony between religion and science, and
his whole attitude towards knowledge, are greatly due to the influence
of St. Thomas and his “brother and master,” Albert of Cologne.

------------------------------------------------------------------------
[123] Albert in _Conv._ III. v. 113-115, vii. 26-28; IV. xxiii. 125-6;
Aquinas in _Conv._ II. xv. 125-6; IV. viii. 3-6, xv. 125-130, xxx.
26-30; _De Mon._ II. iv. 5-8; and see _Purg._ xx. 69.
------------------------------------------------------------------------

There are also three of Dante’s own fellow-countrymen and
contemporaries whose books he is most likely to have read, although he
does not mention them:—Brunetto Latini the Florentine, Cecco d’ Ascoli,
professor at Bologna, and Ristoro the monk of Arezzo.

Brunetto Latini is only mentioned once in Dante’s works, besides the
passage in the _Inferno_ already referred to. In the _De Vulgari
Eloquentia_ Brunetus Florentinus is mentioned with admiration as a
distinguished man of letters, but blamed with other Tuscans for writing
in his own local dialect.[124] Brunetto, who was born in Florence
about 1210, was sent on an embassy in 1260 to Alfonso X. of Castile,
the learned king under whose guidance the famous astronomical Tables
had been drawn up. But on his way back to Florence he was met by the
news that the Florentine Guelphs had been defeated at the disastrous
battle of Montaperti,[125] and expelled from Florence; and as he
belonged to this party he took refuge in France, first at Montpellier
and afterwards in Paris. When the Guelphs had regained the ascendancy
through their victory at Benevento in 1266 (where Manfred lost his
life),[126] Brunetto returned to Florence, and his name subsequently
appears in no less than thirty-five public documents as having been
consulted by the government of his native city on various important
matters. For the most part, moreover, it is recorded that his advice
was followed. He died at a venerable old age in Florence in 1294, and
was buried in the church of Santa Maria Maggiore.

------------------------------------------------------------------------
[124] _V. E._, I. xiii. 1-11.

[125] _Inf._, xxxii. 81, and x. 85, 86.

[126] _Purg._, iii. 112-129.
------------------------------------------------------------------------

It was while exiled in France that Brunetto wrote the Italian poem
_Il Tesoretto_, in which he represents himself as a pilgrim on
an allegorical journey; and from this Dante perhaps derived some
suggestions for his Vision. The poem is incomplete, and breaks off
at a tantalizing point, for Brunetto has just met Ptolemy on Mount
Olympus, and has put a question to him: Ptolemy “rispose in questa
guisa”[127]—and here the poem ends!

------------------------------------------------------------------------
[127] “Replied after this fashion.”
------------------------------------------------------------------------

In France also he wrote _Li Louvres dou Trésor_, a great compendium of
learning, in French prose. The first part treats of the Creation and
Biblical history, and of the natural sciences; the second of ethics,
rhetoric, and politics. In the section on astronomy which is included
in the first part, Brunetto gives a very brief account of Ptolemy’s
system, and the sizes and distances of the heavenly bodies as estimated
by the Arabs: it seems to be based chiefly on Alfraganus. But beside
the periods of the planets he adds in each case their astrological
properties, as for instance:—

    “Saturnus, qui est le souverain sor tous, est cruex
    et felons et de froide nature ... Jupiter ... ast
    dous et piteus et plains de biens.... Mars et chaus
    et bataillereus, et mauvais, et est apelez Diex de
    batailles.”[128]

------------------------------------------------------------------------
[128] _Li Louvres dou Trésor_, Chabaille, Paris 1863.
------------------------------------------------------------------------

When speaking of the two principal movements of the skies, he quotes
a curious old idea which had been mentioned by Isidore of Seville,
that they are in contrary directions because the tremendous speed of
the diurnal motion would shake the whole universe to pieces if it were
not that the seven planets go as it were to meet it, and soften its
vehemence:—

    “Li firmamenz court de orient en occident entre
    jor et nuit une fois, si roidement et si fort
    que sa pesanteur et so grandor la feroient tout
    tressaillir, se ne fussent les VII. planetes qui
    vont aussi comme a l’encontre dou firmament, et
    atemprent son cours selonc son erre.”[129]

------------------------------------------------------------------------
[129] _Ibid._
------------------------------------------------------------------------

The _Acerba_ of Cecco d’Ascoli was another encyclopædic work, but in
Italian verse. It was very much the fashion in those days to undertake
a compilation of all kinds of knowledge, and this was doubtless very
useful when few books could be owned by any single reader. Cecco had a
considerable knowledge of natural science, and astrology was of great
importance in his eyes. Though Dante never mentions him or his work,
he can hardly have been ignorant of it, especially as he himself is
mentioned in it.

Nor does he mention Ristoro of Arezzo, yet we find many ideas and
expressions in Dante’s writings which are also in the _Composizione del
Mondo_. Even if he did not borrow from it, the book is worth study by
anyone interested in the popular astronomy of the thirteenth century.
We learn from the author that he wrote his book in Arezzo, finishing it
in the year 1282, that is about thirty years before Dante’s _Convivio_
appeared. The opening words run:—

    “Incominiciasi il libro della Composizione del
    Mondo colle sue cagioni: composto da Ristoro di
    Arezzo in quella nobilissima città ... etc.”[130]

------------------------------------------------------------------------
[130] “Here beginneth the book of the _Composition of the World
together with its Causes_: written by Ristoro of Arezzo in that most
noble city.”
------------------------------------------------------------------------

and the closing words are:—

    “Compiuto e questo libro sotto li anni di Cristo
    nel mille dugento ottantadue. Ridolfo imperadore
    aletto. Martino quarto papa residente. Amen.”[131]

------------------------------------------------------------------------
[131] “Here endeth this book, in the year of our Lord one thousand
two hundred and eighty-two. Rudolph Emperor at this date. Martin IV.
resident Pope.” Amen.
------------------------------------------------------------------------

We learn further that he was a monk and a native of Arezzo in an
interesting passage where he describes a total eclipse of the sun seen
by himself from his monastery: the sky was very clear, and it must
have been a specially dark eclipse, for besides Mercury he saw many
stars; totality lasted for as long as a man could easily walk 250
steps; there was a feeling of chill, and birds and wild animals were so
frightened that they allowed themselves to be caught. Fra Ristoro made
a calculation and found that on that day sun and moon were in the same
position in the sky. It was perhaps this event which induced him to
study astronomy.

The extent and depth of Ristoro’s reading evidently bore no comparison
to Dante’s, but he was able to sit writing in his quiet cell, day after
day, and had such books as he wanted at hand. The monastery seems
to have been furnished with astronomical tables, a celestial globe,
and the books of Alfraganus and other Arab writers. All these he had
studied, and he was something of an observer too. Alfraganus must have
been always at his elbow when writing, for he turns to it constantly,
quoting (unlike Dante) the chapter referred to:—

    “Alfragano pose nell’ ottavo capitolo;” “è
    testimonio l’Alfragano nelli venti e due capitoli
    del suo libro;”[132]

------------------------------------------------------------------------
[132] “Alfraganus said in the 8th chapter”; “Alfraganus bears witness
in the 22nd chapter of his book.”
------------------------------------------------------------------------

one chapter is avowedly taken whole from Alfraganus, and where the
opinions of “il grande Tolommeo”[133] are quoted they are evidently
copied from the same source. Other Arab writers are quoted once or
twice, for instance, Albumassar,

------------------------------------------------------------------------
[133] “The famous Ptolemy.”

    “il quale fu altissimo maestro d’astrologia,”[134]

[134] “Who was a very great teacher of astrology.”
------------------------------------------------------------------------

and several lines are copied from a Latin translation of Algazel,[135]
giving some astrological jargon about the twelve zodiacal signs.

------------------------------------------------------------------------
[135] “An Arabian philosopher of Baghdad, 1058-1111.”
------------------------------------------------------------------------

We have already quoted from Ristoro’s preface, showing the high
opinion he held of astronomy. But it is disappointing to find that the
greatest part of his book is devoted to the “cagioni,” that is, to
purely fanciful “reasons,” for all the facts and fallacies concerning
nature which he has here brought together.

He gravely argues about the constellation figures as if they were real
pictures of animals and things pricked out by nature in stars on the
vault of heaven, and not a human convention. He notes their paucity in
the southern hemisphere, and that nearly all have their heads towards
the north, and from this he draws the conclusion that the northern part
of the sky is the nobler, for we can see it is the upper side, just as
we know the top side of a book by the position of its letters.

It is for this reason, he thinks, that only the northern hemisphere of
the earth contains land and is inhabited. Some, especially the great
Averroës, had indeed held that there is inhabited land south of the
equator, because the sun goes there. But this is because his movements
of recession and approach are necessary to produce the seasons, and
hence the growth of plant life, in the north. The constellations are
upside down for the south, so they can have no effect there, therefore,
there are no animals there (since every race of animals is under the
protection of a constellation); therefore no plants, since they exist
for animals, and therefore, Ristoro concludes his chain of argument
triumphantly, there are no men, and no lands, for land without life
would be useless.

Ristoro reproduces Alfraganus’ description of the sun’s movements as
seen in different latitudes, quotes him as saying that the equatoral
regions are inhabited, and Avicenna that the temperature there is
equable because days and nights are always equal. The city Arym which
is exactly on the equator has a perfect climate, and as it has two
summers and two winters there are two harvests; moreover, all the stars
in the sky are visible at the equator; therefore, the best astronomers,
and the wisest and richest men, ought to live there, says Ristoro. When
writing thus, he seems to have had before him one of the “climate maps”
which were common in Europe in the eleventh and following centuries,
having been introduced by Arab cartographers, who adopted the idea from
Greek maps. For he goes on to point out that the first “climate” is
much the longest, and that the others diminish gradually towards the
pole, all the “terra scoperta”[136] being thus contained in one quarter
of the earth, and having the shape of the moon when we see it half
full.[137]

------------------------------------------------------------------------
[136] “The uncovered earth,” _i.e._ not hidden under the ocean.

[137] Bk. VI. cap. xi.
------------------------------------------------------------------------

[Illustration: Fig. 38. The half-moon shape of the habitable earth.
(Ristoro).

    There is nothing but sea south of the equator, and
    the habitable earth lies wholly in one half of the
    northern hemisphere, the other half being sea. The
    habitable earth, therefore, is the same shape as
    the half-moon, _i.e._ a quarter sphere.]

The accompanying climate map shows all these features, the famous
city Arym—occupying nearly half the space, although it is supposed to
be merely on the equator—the seven climates, and the region beyond the
seventh, near the north pole, marked as uninhabitable through the cold.
The half-moon shape of Earth’s habitable quarter is obvious. The map
betrays Arab influence in the orientation, the south being at the top;
and Arym, or Aren, was an Arab myth, perhaps derived from the Mount
Meru of the Hindus, which is said in the Vedas to be “in the middle of
the earth.”

According to Ristoro, the positions of the constellation figures do
not only explain why one hemisphere of earth has land and the other
none; they also explain the movements of the skies. For the figures
of the zodiac face west (those that have faces), and this is why the
diurnal movement of the whole heaven is towards the west, so that the
constellations may move straightforward, in the natural way. On the
other hand, the planets move in the opposite direction because it would
not be seemly for them to pass each figure of the zodiac arriving first
at the back and moving on to the head. This is the true reason of the
contrary direction of the two principal celestial movements. Ristoro
does not approve of the solution quoted by Brunetto Latini. He adds
that the width of the zodiac was designed to contain the figures of the
animals!

After this, we are not surprised to hear that the red colour of the
planet Mars is the cause of its martial nature (not the reason for
which such a nature is attributed to it). The markings on the moon
Ristoro explains by saying that some body must exist in the World
which is neither polished and shining all over, like the stars, nor
altogether rugged and dark, as the earth was supposed to be, but
partaking of both natures; and this body must be the moon, because of
her intermediate position between the earth and the nearest of the
other planets (Mercury).

[Illustration: CLIMATE MAP, OF ABOUT A.D. 1110. [_To face p. 248._

_Reproduced by permission from Beazley’s “Dawn of Modern Geography.”_]

Of the influence of the heavens on the earth Ristoro has very much to
say, from general statements such as that the spheres impress their
influence on things of Earth, just as a seal impresses wax, down to
details about the births of horses. If the moon is strong in Aries,
and Aries is powerful, then, because the moon signifies white among
the colours and Aries signifies the head, the horse will be born
with a white mark on its head, and if the influence is very strong
it will be a beautifully-shaped mark. Again and again he tells us
about the various properties and “virtues” of the seven planets, but
he does not omit to mention that the powers which move the planets
and cause them to influence Earth are spirits, which we call Angels,
and the philosophers call Intelligences. These have their several
dwelling-places in the spheres, and the nobler their nature the higher
is the sphere which they inhabit.

From these quotations the reader may judge of the general trend of the
eight books comprised in _La Composizione del Mondo colle sue Cagioni_:
we shall have occasion to refer to it again, by way of comparison and
contrast, when dealing with Dante’s works in detail.

It is rather curious that there is no trace in Dante’s writings of
acquaintance with the great Roger Bacon, or with Sacrobosco, especially
as Brunetto Latini knew the former personally, and Cecco d’Ascoli
wrote a commentary on the latter, but Dante may have known them, and
also the works of Isidore and Bede, who are both mentioned in _Par._,
x. 131, as well as other books which are now completely lost. Those we
have described above would, however, be enough to supply him with all
the astronomical data, except one, which we find in his writings. It is
now time to examine these, and see what use he made in literature of
the knowledge he possessed.


_IV. ASTRONOMY IN DANTE’S WRITINGS._

ASTRONOMY IN DANTE’S WRITINGS.

If we except the seven _Penitential Psalms_ and the _Profession of
Faith_, which are only paraphrases, and are very doubtfully ascribed
to Dante, no work of his can be mentioned which does not contain some
reference to the heavenly bodies.

When writing the _Vita Nuova_, that story of his love for Beatrice
which he calls the work of his boyhood,[138] he was haunted by the
sublime idea of the rolling spheres. Beatrice at her first appearance
as a little girl of eight, and Beatrice when she died, suggested
thoughts of the nine heavens;[139] almost the first words of the book
allude to the circling spheres of the sun and of the stars:[140] and
the last sonnet soars beyond them all to the Empyrean.[141] Already he
seems to have read Alfraganus, for he takes a suggestion which occurs
in the first chapter of the _Elementa Astronomica et Chronologica_.
Alfraganus there describes the different methods of reckoning days,
months, and years, in use among different nations, and gives a special
list of the Syrian months with their corresponding Roman months; and
Dante, by using the Arabian system of days and the Syrian months, is
able to prove to himself that the day and the month when Beatrice died
were both at the sacred number of nine.[142] According to our method of
reckoning, the time was sunset on the eighth of June, but this was the
first hour of the ninth day according to Arabian usage, and our sixth
month corresponds with the ninth of the Syrians.

------------------------------------------------------------------------
[138] _Conv._ I. i. 125, 126. Compare _Conv._ IV. xxiv. 1-13.

[139] _V. N._ ii. 9-12, xxx. 13-24.

[140] _V. N._ ii. 1-12.

[141] _V. N._ xlii. 47.

[142] _V. N._ xxx. 1-6.
------------------------------------------------------------------------

Dante had also read at this time Aristotle’s doctrines about the
spheres and their Movers, for he quotes from the _Metaphysics_,[143]
and this is the work in which they are found.

------------------------------------------------------------------------
[143] _V. N._ xlii. 30.
------------------------------------------------------------------------

Yet a familiarity with Alfraganus and Aristotle so early as this is
hardly consistent with the difficulty he says he found in understanding
Latin books of philosophy some time after the death of Beatrice.[144]
Perhaps the latter part of the _Vita Nuova_ was written a good deal
later; or it may be not altogether frivolous to suggest that in his
youth Dante had read the first chapters of Alfraganus, which are easy,
but did not master the rest of the book till later.

------------------------------------------------------------------------
[144] _Conv._ II. xiii. 22-26.
------------------------------------------------------------------------

Out of his fifty-three short poems (including all in Moore’s Oxford
Edition, except those which form part of the _Vita Nuova_ or
_Convivio_), twelve, or nearly a quarter, contain some reference to
sun, moon, or stars, planets, or spheres; and from these alone we could
form some idea of Dante’s acquaintance with astronomy. He speaks of
the sun as measuring time,[145] and giving light to the stars[146]
(according to the general belief); the moon[147] and each of the
planets[148] is mentioned, some of the constellations also,[149]
especially with reference to the seasons; the theory of the several
heavens and their First Mover,[150] and the supposed influences of the
stars and planets are alluded to.[151] These poems were written at
different times, and some belong to a much later period than the _Vita
Nuova_.

------------------------------------------------------------------------
[145] _Son._ xxxvi. 2; _Canz._ xx. 89.

[146] _Canz._ xix. 117; _Canz._ ix. 16, 17.

[147] _Canz._ xx. 89; _Son._ xxviii. 11.

[148] _Son._ xxviii.; _Canz._ xv. 4, 7.

[149] _Canz._ xv. 3, 29, 41.

[150] _Son._ xxviii. 2.

[151] _Son._ xxviii. _Canz._ xix. 77, _Ball._ vi. 11, 12, _Canz._ xv.
41., _Son._ xxvi. 14.
------------------------------------------------------------------------

It is when we come to examine the _Convivio_, the work of his
manhood,[152] that we find the clearest evidence of Dante’s careful
study of astronomy. This book was written with the professed intention
(as one of its aims) of sharing with others the learning he had been
happy enough to acquire—not indeed as one of the guests at the Table
of Wisdom, but as one sitting at their feet and gathering up the
crumbs.[153] The thread which connects his discourse is a collection
of his own Odes, on each of which he had intended to write a treatise
or commentary, but the book never advanced beyond the fourth treatise.
These Odes were nearly all love-poems, but the poet explains that
they are a figurative expression of his devotion to Philosophy, and
the whole book is a glorification of the pursuit of knowledge. In the
opening sentences, with the reference to Aristotle, the manner of
reasoning, the assumptions of our innate desire for absolute knowledge
and the bliss brought by its attainment, Dante is the spokesman of his
period.

------------------------------------------------------------------------
[152] _Conv._ I. i. 111-113 and 125-127.

[153] _Conv._ I. i. 67-86.

    “Siccome dice il Filosofo nel principio della
    _Prima Filosofia_, Tutti gli uomini naturalmente
    desideranno di sapere: La ragione di che puote
    essere, che ciascuna cosa, da providenza di
    propria natura impinta, è inclinabile alla sua
    perfezione. Onde, acciochè la scienza è l’ultima
    perfezione della nostra anima, nella quale sta la
    nostra ultima felicità, tutti naturalmente al suo
    desiderio siamo soggetti.”[154]

[154] “As the Philosopher says at the beginning of the _First
Philosophy_, ‘All men naturally desire to have knowledge.’ The reason
of this may be that everything, being impelled by foresight belonging
to its own nature, tends to seek its own perfection. Wherefore inasmuch
as knowledge is the final perfection of our soul in which our final
happiness consists, all men are naturally subject to the desire for
it.” _Conv._ I. i. 1-11.
------------------------------------------------------------------------

And from a study of the _Convivio_ we may learn much of the authors
most esteemed, the methods of study pursued, and the results obtained,
by thirteenth-century scholars seeking to gain the ultimate perfection
of the soul.

Astronomy is frequently introduced, especially in the second and third
treatises. The Ode which forms the text of the second treatise is
that which is quoted by Charles of Hungary in _Par._ viii. 37—“Voi
che intendendo il terzo ciel movete,”[155] and it gives Dante the
occasion to speak first of the heaven of Venus, explaining Ptolemy’s
system of epicycles, and later of all the heavens in their order, and
the celestial bodies contained in them. The ode of the third treatise
contains the line “Non vede il Sol, che tutto il mondo gira ...”[156]
and upon this he hangs a complete little essay describing the movements
of the sun, and how they appear from different parts of the earth, as
well as a short dissertation on the question whether it is Sun or Earth
which actually moves.

------------------------------------------------------------------------
[155] “Oh ye whose intellectual ministry
       Moves the third heaven.”—_Carey._

[156] “The sun sees not, though circling all the world.”
------------------------------------------------------------------------

The Latin works, _De Monarchia_, _De Vulgari Eloquentia_, the
_Eclogues_, and the _Letters_, do not give much scope for astronomical
references; yet there are many similes drawn especially from the sun
and moon, and the thought of the spheres as instruments of God’s Will
in bringing about events on earth is constantly recurring. In the
curious work _Quæstio de Aqua et Terra_, Dante argues learnedly about
the spheres, the orbit of the moon, and her effect on the tides, and
the influences of the stars. The book purports to have been written at
Verona in 1320 as the outcome of a discussion in which Dante had taken
part as to the respective heights of land and ocean, a problem which
had been dealt with by Ristoro d’ Arezzo some forty years earlier. Its
authenticity has been questioned, partly under the mistaken idea that
facts such as gravity, the spherical form of Earth, and the connection
of tides with the moon were not known until much later; but as a matter
of fact the discussion is quite in the manner of Dante’s day, and no
facts or theories are put forward which he could not have learned
from books with which we believe he was acquainted.[157] The internal
evidence of his authorship is strong, and belief in it seems to be
gaining ground among experts.[158]

------------------------------------------------------------------------
[157] The spherical form of Earth, and the action of gravity at the
earth’s surface, were commonplaces with the Greeks, as we have seen
in Part I. of this book. Posidonius, Strabo, and other classical
writers speak of the tides as following the revolution of the heavens,
and having periods similar to those of the moon; Albertus Magnus and
Aquinas ascribe them to the influence of the moon, and so does Dante
himself in _Par._ xvi. 83.

[158] See Moore, _Studies in Dante_, II. “The Genuineness of the
_Quæstio de Aqua et Terra_,” for a complete discussion of the question.
------------------------------------------------------------------------

Finally, the _Divine Comedy_, the work of Dante’s maturity, which took
him so many years to write, and for which he had studied ever since he
closed the _Vita Nuova_ with the resolve to write more worthily one day
of Beatrice,[159] focuses in one unique and finished work the thoughts
and ideals, the knowledge and fancies, of the poet and his age. The
subject of the poem, taken in its literal sense, is cosmical, for it
describes a journey in which the author penetrates to the centre of
the universe, and passes from planet to planet until he reaches the
outermost sphere. Moreover, the journey is assumed to take a definite
space of time, and the passing of the hours by day and by night is
indicated by the successive positions of sun or stars, and the phases
and movements of the moon. The _Divine Comedy_ contains more than twice
as many allusions to the heavenly bodies as all the other works of
Dante put together.

------------------------------------------------------------------------
[159] _V. N._ xliii. 3-7.
------------------------------------------------------------------------

But we must discriminate in drawing conclusions from these
astronomical references so freely distributed in all Dante’s writings.
If he wrote the _Quæstio_, it is his only professedly scientific
work, written for scientific men, and astronomy is only brought in
incidentally. The _Convivio_, in which astronomical facts and theories
are set forth in much greater detail and fulness than elsewhere, was
a popular work meant for those who had no inclination, or else no
opportunity, for prolonged serious studies. We expect, therefore, that
technical details will be avoided. Still more will they be omitted in
the _Divine Comedy_ and other poetical works, where difficult problems
and pedantical accuracy would be most unsuitable. We can _infer_ the
knowledge which lay in Dante’s mind, behind his popular use of it in
literature; and we can often find an explanation in the prose of the
_Convivio_ for a slight allusion in the poetical works; but we must
not deal with any as if they were text-books, and set forth precisely
and completely all that Dante knew of his favourite science. It is
the poet’s artistic use of the astronomy of his day which merits our
admiration quite as much as the scholar’s proficiency.

This being premised, we may now proceed to quote from his works,
showing how he has dealt with first the facts, and secondly the
theories, of astronomy. Finally we shall be able to form a clear mental
picture of the universe as it was believed to exist by Dante, and not
only by his contemporaries but by his successors for many generations.


_V. OBSERVATIONAL ASTRONOMY._

    “The heavens declare the glory of God; and the
    firmament sheweth His handy-work. Day unto day
    uttereth speech, and night unto night sheweth
    knowledge. There is no speech nor language where
    their voice is not heard. Their line is gone out
    through all the earth, and their words to the end
    of the world. In them hath he set a tabernacle for
    the sun; which is as a bridegroom coming out of his
    chamber, and rejoiceth as a strong man to run a
    race.”


1. MOVEMENTS OF THE MOON.

Of all the seven sciences of the Trivium and Quadrivium, Astronomy,
Dante thought, was the noblest, and for two reasons. Aristotle had said
that a science is noble in proportion to the nobility of its subject,
and the certainty of its conclusions; and in both of these Astronomy
excels. Its subject is the Movement of the Heavens, and its certainty
is perfect. “E nobile e alta per nobile e alto suggetto, ch’è del
movimento del cielo: è alta e nobile per la sua certezza, la quale è
senza ogni difetto.”[160] If astronomers are sometimes mistaken, the
fault lies in them, as Ptolemy said, and not in the science.

------------------------------------------------------------------------
[160] _Conv._ II. xiv. 244-217. “It is noble and lofty because of its
noble and lofty subject, which is the movement of the heavens; it is
lofty and noble because of its certainty, which is without flaw.”
------------------------------------------------------------------------

This quotation from Ptolemy is from his book on “judicial
astronomy,”[161] and it may be that Dante was partly thinking of
astrological predictions, as he almost certainly was in the passage
that follows, where he adds that astronomy takes a long time to
learn, not only because of its great range, but because experience is
necessary to form a correct judgment. Nevertheless, it is probable that
by its flawless certainty he meant that unchanging laws govern the
celestial phenomena, so that they may always be predicted without error
when the laws are known.

------------------------------------------------------------------------
[161] See p. 156.
------------------------------------------------------------------------

His definition of astronomy was accurate, for it was not until the
middle of the nineteenth century that physical astronomy began to take
its place beside the old “astronomy of position,” and in Dante’s day
practically the only subject open to research concerning the heavenly
bodies was their movements. Of these, and especially the “prime motion”
of the diurnal revolution, he was vividly conscious. His favourite name
for the heavens is “wheels”—“le ruote magne,” “eterne ruote,” “stellate
ruote”;[162] and he often refers to them as a standard of motion. Thus
when with Beatrice he was rapt from the summit of Mount Purgatory, to
express the swiftness of their flight he says it was almost as rapid
as the movement of the sky—“veloci, quasi come il ciel vedete.”[163]
Constantine moving the capital of the Roman Empire eastwards is
described as turning the Roman Eagle contrary to the course of the
sky—“contra il corso del ciel,”[164] and the sky itself is described as
a sphere which is ceaselessly at play like a lively child:—

------------------------------------------------------------------------
[162] “The great wheels,” “eternal wheels,” “starry wheels.”

[163] “Swift, almost as the heaven ye behold.” _Par._ ii. 21.

[164] “Against the course of the sky.” _Par._ vi. 2.

                           ... “la spera,
    Che sempre a guisa di fanciullo scherza.”[165]

[165]                         ... “That sphere,
    Which aye in fashion of a child is playing.”
                                _Purg._ xv. 2, 3. (_Longfellow_).
------------------------------------------------------------------------

To Dante, as to the Greeks, it is not the unusual or startling that
appeals, but the unfailing harmony of the regular celestial movements.
Comets he mentions only twice, and shooting stars twice, eclipses seven
times; but there are scores of allusions to the rhythmical progression
of Sun and stars, Moon and planets. The skies were familiar to him
in all their daily aspects—sunset and dawn and radiant noons; cloudy
nights “sotto pover cielo,”[166] brilliant starlit nights, nights of
clear moonlight. He had seen the stars fade one by one, till at last
even the brightest vanished in the glow of dawn:—

------------------------------------------------------------------------
[166] “Under a poor sky.” _Purg._ xvi. 2.

    “E come vien la chiarissima ancella
    Del sol più oltre, così il ciel sì chiude
    Di vista in vista, infino alla più bella.”[167]

[167] “And as advances, bright exceedingly,
       The handmaid of the sun, the heaven is closed,
       Light after light, to the most beautiful.”
                           _Par._ xxx. 7-9. (_Longfellow_).
------------------------------------------------------------------------

he had watched for their first appearance in the evening twilight:—

    “E sì come al salir di prima sera
    Comincian per lo ciel nuove parvenze,
    Sì che la vista pare e non par vera....”[168]

------------------------------------------------------------------------
[168]                      “As at evening hour
      Of twilight, new appearances through heaven
      Peer with faint glimmer, doubtfully descried.”
                              _Par._ xiv. 70-72. (_Carey_).
------------------------------------------------------------------------

Numberless other passages and expressions will occur to every Dante
reader, proving how keenly he felt the beauty of the skies.

But they prove more than this. Other authors have felt and have
described poetically the beauties of the skies, but they often remember
imperfectly what they saw, or draw upon their imagination without any
knowledge of the celestial movements, and so fall into absurd mistakes.
The moon especially is a stumbling-block, and it is quite a rare thing
for a modern novelist to introduce one without making it do something
impossible. A new moon will rise at midnight, or a waning moon at
sunset; she has even been known to rise and then to set in the dark
hours of one short midsummer night;[169] and a well known author sees
her in two phases at the same moment: “the full moon rose, yellow _and
gibbous_!”[170]

------------------------------------------------------------------------
[169] In Kenneth Grahame’s delightful book, full of sympathy with
Nature, _The Wind in the Willows_. The moon rose when it was “past ten
o’clock,” and “sank earthwards reluctantly and left them” before dawn.

[170] H. G. Wells, _The Time Machine_.
------------------------------------------------------------------------

Dante’s moon does indeed give us a little trouble once or twice, but
he never makes flagrant mistakes of this kind. His consistency and
truth of description prove his knowledge of astronomy, and also imply
intelligent thoughtful watching of the celestial movements; for it
is notorious that book-knowledge, if unassisted by acquaintance at
first-hand with the facts of a subject like astronomy, will not save a
writer from glaring inaccuracies.

His allusions to the motions of the moon, both diurnal and monthly,
show plainly that he understood them well. His new moon appears in
the evening, his waning moon rises late at night and sets in morning
sunshine,[171] and his full moon comes on the meridian at midnight, for
when he wishes to describe her at her brightest, as a comparison with a
very brilliant light, he places her in a clear sky at midnight in her
mid-month.[172] In the middle of a lunar month the moon is full, and
being exactly opposite the sun will reach the meridian at midnight:
this therefore is the time when she gives all the light she possibly
can. In the _Quæstio_[173] Dante mentions that the moon does not move
in the celestial equator, but sometimes north of it, and sometimes an
equal amount south; in the _Convivio_ he indicates the length of her
period, and briefly describes her phases and their cause—“Ora luce da
un lato, e ora luce dall’ altro, secondo che ’l sole la vede.”[174]

------------------------------------------------------------------------
[171] _Inf._ xv. 18, 19; _Purg._ xviii. 76-81; _Purg._ x. 14, 15, _Cf._
ix. 44.

[172] _Purg._ xxix. 53, 54.

[173] _Qu._ xx. 61-63.

[174] “Now she shines on one side, and now on the other, according to
the way the sun looks upon her.” _Conv._ II. xiv. 77-79.
------------------------------------------------------------------------

Her position in the zodiac is mentioned several times. In one passage
he indicates a very brief space of time in the following curious way:—

    “Quando ambo e due i figli di Latona,
        Coperti del Montone e della Libra,
        Fanno dell’ orizzonte insieme zona,
    Quant’ è dal punto che il zenit inlibra.
        Infin che l’uno e l’altro da quel cinto,
        Cambiando l’emisperio, si dilibra,
    Tanto, col volto di riso dipinto,
        Si tacque Beatrice.”[175]

------------------------------------------------------------------------
[175]
    “At what times both the children of Latona,
        Surmounted by the Ram and by the Scales,
        Together make a zone of the horizon,
    As long as from the time the zenith holds them
        In equipoise, till from that girdle both
        Changing their hemisphere disturb the balance,
    So long, her face depicted with a smile,
        Did Beatrice keep silence.”
                                _Par._ xxix. 1-8.
------------------------------------------------------------------------

That is to say, when Sun and Moon (the children of Latona) are both
on the horizon, but one being in Aries and the other in Libra they
are opposite one another, the zenith for a moment holds them, as it
were, in balance; but the next moment one will drop below the horizon
while the other rises above it, thus changing from the visible to
the invisible hemisphere and _vice versa_, as each frees itself (“si
dilibra”) of the common horizon that girdled them. The pause of
Beatrice was as brief as the time during which sun and moon would thus
hang in the balance.

Yet, though Dante shows that he was familiar with the movements
and appearances of the moon, his allusions to her are cold and
comparatively rare. Unlike modern poets, moonlight does not seem to
have had any great fascination for him. In all his works there are
only fifty-one references to the moon, and far the greater number of
these are remarks about the measurement of time, or else her phases,
her markings, her share in causing eclipses etc. In all his short poems
(including those of the _Vita Nuova_ and _Convivio_) there are but two
references, and those as dry as possible. “Più lune”[176] is once used,
meaning several months, and in a sonnet which describes the influences
of each heaven on his lady, all he can find to say of the moon’s is “E
’l primo ciel di sè già non l’è duro.”[177]

------------------------------------------------------------------------
[176] “Many moons.” _Canz._ xx. 89.

[177] “And the first heaven is not grudging to her.”—_Sonetto_ xxviii.
------------------------------------------------------------------------

The chill of moonlight is spoken of as with a shudder on the hill of
Purgatory;[178] and its usefulness is recognized rather grudgingly
when Virgil remarks that yesternight the moon was full, and adds that
Dante must remember it, since it did him no harm in the depths of the
Forest.[179] It is true there is some beauty in the description of the
aurora which preceded moonrise[180] on the first night in Purgatory,
but Dante gives it an ugly name, and the waning moon when seen on the
following night, four days after full, is oddly compared to a bucket
in shape. Dante did not admire this gibbous form, for he instances
the outline of the moon when not quite full as an ignoble curve,
contrasting it with the beauty of a perfect circle.[181]

------------------------------------------------------------------------
[178] _Purg._ xix. 1, 2.

[179] _Inf._ xx. 127-129.

[180] _Purg._ ix. 1-9.

[181] _Conv._ IV. xvi. 89-93.
------------------------------------------------------------------------

[Illustration: Fig. 39. Sun, moon, and zenith.

To illustrate _Par._ xxix. 1-6. (_See p. 265_).

In the first figure the sun and moon are balanced, as it were, being at
equal distances from the zenith: in the second, a few minutes later,
by the rising of the sun and the setting of the moon, the balance is
disturbed, and each changes its hemisphere.]

Hardly ever does he find a beautiful epithet for her: she is ruler of
Hell,[182] Cain and the Thorns[183] (in reference to the legend which
sees this figure in her dark markings); or she is simply Delia,[184]
Trivia,[185] the daughter of Latona,[186] or with a little warmth
the sister of the sun,[187] and with the sun one of the two Eyes of
Heaven.[188] One exception to this harsh treatment is in the beautiful
description of reaching the heaven of the moon,[189] for there she is
the first star, the eternal pearl; and the sudden burst of eloquence in
the midst of a grave argument in _De Monarchia_ startles us doubly when
we find that Justice is compared to the moon—not, as one might expect,
resplendent in a dark sky, but Phœbe gazing at her brother opposite,
in the purple of the morning calm.[190] The passage from _Par._ xxix.
quoted above helps us to understand why the moon in this position
should symbolize Justice, for here again is suggested the perfect
balancing of the two great orbs, as the sun rises and the full moon
sets.

------------------------------------------------------------------------
[182] _Inf._ x. 80.

[183] _Inf._ xx. 126.

[184] _Purg._ xxix. 78; _Ep._ vi. 54.

[185] _Par._ xxiii. 26.

[186] _Par._ x. 67; xxii. 139; xxix. 1.

[187] _Purg._ xxiii. 120.

[188] _Purg._ xx. 132.

[189] _Par._ ii. 25-36.

[190] _De Mon._ I. xi. 35-37.
------------------------------------------------------------------------

Add to these passages two similes drawn not indeed from the moon
itself but from the halo surrounding her,[191] and two descriptions
of brilliant moonlight nights,[192] and we have all that Dante has
written in praise of the moon. It is true that throughout the _Inferno_
and _Purgatorio_ the sun typifies Divine Grace, and the moon is his
opposite, but this cannot altogether explain the difference in their
treatment, even in the _Divine Comedy_. A deeper reason seems to be
Dante’s true southerner’s love of the sun; and he doubtless had the
astronomer’s feeling that moonlight always means loss of starlight,
which he dearly loved (see _Purg._ xviii. 76, 77). Perhaps too the
astrological views of the moon influenced him, consciously or not.
According to Ristoro, the moon represents the poorest and lowest
classes of people, who are servants and messengers to the rest; and as
all the planets were supposed to be either masculine or feminine, he
ungallantly adds—“E questa Luna, a cagione di sua viltà, potemo dire
per ragione ch’ella sia femmina.”[193] Her only house, too, which is
Cancer, is also poor and base. The moon, moreover, is nearer Earth than
any other planet, and shows by her dark markings that she is less pure
than the rest.

------------------------------------------------------------------------
[191] _Par._ x. 67-69; and _Purg._ xxix. 78.

[192] _Purg._ xxix. 53, 54; and _Par._ xxiii. 26.

[193] “And this moon, because of her inferiority, is rightly called
feminine.”
------------------------------------------------------------------------


2. MOVEMENTS OF THE SUN.

Whatever the reason, Dante’s fifty-one references to the moon are in
strong contrast to his allusions to the sun. These are four times as
many, and they include warm expressions of admiration and delight,
and beautiful epithets and similes. The sun is Titan with his chariot
and horses,[194] he is a Mirror, a Car of Light, the Lantern of the
World, the Prince of the Stars, the Father of all mortal life.[195] His
beautiful form is admired, “la perfetta sua bella figura,”[196] and his
intense brilliance often noted.[197] He is the guide that leads all
aright,[198] to whom Virgil appeals:—

------------------------------------------------------------------------
[194] _Ecl._ ii. 1-4.

[195] _Purg._ iv. 62, 63; _Purg._ iv. 59; and xxix. 117, 118; _Par._ i.
38; _Canz._ xix. 114; _Par._ xxii. 116.

[196] “The perfection and beauty of his shape.” _Canz._ xix. 76.

[197] _V. N._ xlii. 29; _Canz._ ix. 2; _Conv._ II. xiv. 126, 127;
_Purg._ xvii. 52, 53; _Par._ i. 54; and x. 48, etc.

[198] _Inf._ i. 17, 18.

    “O dolce Lume, a cui fidanza i’ entro
    Per lo nuovo cammin, tu ne conduci.”[199]

[199]
    “O pleasant light, my confidence and hope!
    Conduct us thou,” he cried, “on this new way.”
                              _Purg._ xiii. 16, 17. (_Carey_).
------------------------------------------------------------------------

Under his rays the rose expands, the air is gladdened, mists are
dispelled, snow melts, and all things are quickened into life.[200]
Unlike the moon, the sun is the bringer of warmth and comfort, chasing
away cold and darkness,[201] sunrise is the hour of renewed hope and
confidence,[202] it strengthens our limbs, paralysed by the cold of
night,[203] it is eagerly awaited through the darkness by the little
bird on her nest;[204] and delicate flowers, bowed and closed during
the cold night, rise upright on their stems and open as soon as the sun
shines once more upon them.[205] The exquisite sunsets and sunrises of
the _Purgatorio_ are favourite passages with all readers.

------------------------------------------------------------------------
[200] _Par._ xxii. 55, 56; _Inf._ vii. 122; _De Mon._ II. i. 37-39; and
_Par._ ii. 106-108; _Canz._ xi. 37; _Conv._ III. xii. 59, 60, etc. etc.

[201] _Canz._ ix. 5.

[202] _Inf._ i. 41-43.

[203] _Purg._ xix. 10, 11.

[204] _Par._ xxiii. 1-9.

[205] _Inf._ ii. 127-129.
------------------------------------------------------------------------

Love is compared with the summer sun,[206] the generosity of a noble
nature resembles “the great planet.”[207] The Emperor Henry VII., from
whom Dante expected the regeneration of Italy and the whole Christian
world, is likened to the rising sun;[208] the birth of St. Francis is
described as “nacque al mondo un sole,”[209] and his birthplace ought
rightly to be called not Assisi but Orient.[210] Virgil is addressed
as “O Sol che sani ogni vista turbata;”[211] Beatrice is “Il sol degli
occhi miei.”[212] Finally the sun is the best symbol of God,[213]
and so it is used many times in the _Divine Comedy_: “Il Sol degli
angeli,”[214] “Il Sol che raggia tutto nostro stuolo;”[215] a spirit
turns to “il Sol che la riempie,”[216] and when Virgil laments that he
is shut out of heaven it is in these words: “Ho i’ perduto Di veder l’
alto Sol che tu disiri.”[217]

------------------------------------------------------------------------
[206] _De Mon._ II. i. 36-41.; _Canz._ ix.

[207] _Canz._ xix. 96-114.

[208] _Ep._ v. 10; and vii. 19, 20, 25.

[209] “A sun rose upon the world.” _Par._ xi. 50.

[210] _Par._ xi. 52-54.

[211] “O sun that healest all imperfect vision,” _Inf._ xi. 91.

[212] “The sun of my eyes.” _Par._ xxx. 75 (See also _Par._ iii. 1-3).

[213] _Conv._ III. xii. 52-63.

[214] “The Sun of the angels.” _Par._ x. 53.

[215] “That Sun which enlightens all our company.” _Par._ xxv. 54.

[216] “The Sun which satisfies it.” _Par._ ix. 8.

[217] “I have lost the sight of that high Sun whom thou desirest.”
_Purg._ vii. 25, 26. Compare _Par._ xxx. 126; xv. 76; xviii. 105.
------------------------------------------------------------------------

But we may not dwell on those thoughts of the sun as the typical giver
of light and life; we must ask what Dante says about his movements,
since this was the chief subject-matter of mediæval astronomy.

His daily course, “il cammin del Sole,”[218] is often spoken of, and
is indicated both by his position in the sky, and the length and
direction of shadows. The second _Eclogue_ begins with a description of
a breathlessly hot midday, when objects, which are usually shorter than
their own shadows, now surpassed them in length.

------------------------------------------------------------------------
[218] “The path of the sun.” _Purg._ xii. 74.

    “Resque refulgentes, solitae superarier umbris,
    Vincebant umbras.” _Ecl._ ii. 5, 6.
------------------------------------------------------------------------

At this time the sun appears most brilliant, and seems to move most
slowly, since he is scarcely changing his position with regard to the
horizon.

    “E più corrusco, e con più lenti passi,
    Teneva il sole il cerchio di merigge.”[219]

------------------------------------------------------------------------
[219] “Shining more brightly and with slower steps, the sun had gained
the circle of midday.” _Purg._ xxxiii. 103, 104.
------------------------------------------------------------------------

The greatest number of references to the sun’s daily journey occur in
the _Purgatory_, and we shall quote them in a later chapter.

His yearly journey through the zodiac is also very often referred to.
When relating his first meeting with Beatrice, Dante names his age, not
by simply saying that he was nearly nine years old, but by counting the
number of the times that the “heaven of light,” that is, of the sun,
had returned to the same point since his birth:—

    “Nove fiate già, appresso al mio nascimento, era
    tornato lo cielo della luce quasi ad un medesimo
    punto, quanto alla sua proprio girazione.”[220]

------------------------------------------------------------------------
[220] “Nine times already since my birth had the heaven of light
returned to the selfsame point almost, as concerns its own revolution.”

    _V. N._ ii. 1-4. (_Rossetti_).
------------------------------------------------------------------------

The sun’s “own revolution” is of course its apparent yearly movement,
as distinct from the diurnal movement which it shares with all the
heavenly bodies.

The same thought is expressed in a sonnet:

    “Io sono stato con Amore insieme
    Dalla circolazion del Sol mia nona.”[221]

We know further that Dante was born in either May or June, because he
says, when he finds himself among the stars of Gemini, that the sun was
rising and setting in this sign at the time of his birth.[222]

------------------------------------------------------------------------
[221] “I have dwelt with Love since my ninth revolution of the sun.”
_Son._ xxxvi. 1, 2.

[222] See diagram on p. 276.

    “O gloriose stelle
    Con voi nasceva e s’ascondeva vosco
    Quegli ch’è padre d’ogni mortal vita,
    Quand’ io senti’ da prima l’ aer tosco.”[223]

[223]

    “O glorious stars ...
    With you was born, and hid himself with you,
    He who is father of all mortal life,
    When first I tasted of the Tuscan air.”
                        _Par._ xxii. 112-117. (_Longfellow_).

At this date the sun entered the _constellation_ of Gemini on June
1 (Old Style), but was in the _sign_ from May 11 to June 11, and it
is always to the signs that Dante refers in the _Divine Comedy_. The
anonymous fourteenth century commentator known as “l’Ottimo” interprets
this passage as indicating the time “between the middle of May and the
middle of June.”
------------------------------------------------------------------------

Boccaccio tells us that a Mayday feast, given by the father of
Beatrice, was the occasion of Dante’s first meeting with her, and also
that not long before his death in Ravenna he told a friend that he had
completed his fifty-sixth year in the preceding May, so we may conclude
that May was the month of his birth.

Dante seems to have taken some trouble to find out the exact period of
the sun’s revolution. His text-book, the _Elementa_ of Alfraganus, only
gives it as 365¼ days nearly:—“Sol ... orbem confecit diebus 365 et
propè ¼.” Ristoro d’Arezzo and Brunetto Latini were content to repeat
this rough estimate, and call the year 365 days 6 hours, but Dante
wished to be more exact, and somehow contrived to obtain a value which
was much nearer the modern estimate of 365 days, 5 hours, 48 minutes,
46 seconds. We know this from two passages. In the _Convivio_ he gives
the half period as less than 182 days 15 hours; and in the _Paradiso_
Beatrice says that January will in time cease to be a winter month,
because of a neglected fraction of time.

    “Prima che gennaio tutto si sverni
    Per la centesma ch’ è laggiù negletta.”[224]

------------------------------------------------------------------------
[224]
    “Ere January be unwintered wholly
    By the centesimal on Earth neglected.”
                     _Par._ xxvii. 142-143. (_Longfellow_).
------------------------------------------------------------------------

January was in fact receding from the winter, and steadily though
slowly advancing towards the spring, because the Julian year (as we
saw, p. 171) was 11 minutes 14 seconds longer than the true solar
tropical year. When Julius Cæsar reformed the Calendar, March 25 was
made (as of old) to coincide with the spring equinox, but by Dante’s
time this date was 13 days late, and the true equinox fell on March 12.
Consequently though the day called January 1 still came 84 days before
March 25, it was only 71 days before the spring equinox.

If Beatrice meant to speak with scientific precision, and was correct
in her hundredth part of a day per annum, that is, if the difference
between the astronomical and the Julian year was one day in a hundred
years, it would be 7100 years before the first of January came to
coincide with the spring equinox, and January became a spring month.
But the error quoted is really rather too large, for a hundredth part
of a day is 14 minutes 24 seconds, and it was in fact only 11 minutes
14 seconds.

It would be interesting to know where Dante found this value, which
is practically the only astronomical datum not given in Alfraganus.
Ptolemy, following Hipparchus, had given the tropical year as ¹/₃₀₀
part of a day less than 365¼; Albategnius gave a more accurate figure,
and one which agrees well with the “centesma,” for his tropical year
differs from the Julian by a little less than ¹/₁₀₆ of a day; but he
also improved the value of precession, and Dante does not seem to have
known this, so he was probably not acquainted with this astronomer’s
work. The Alfonsine Tables gave a value which was very close indeed to
the correct one, making the tropical year only 30 seconds longer than
the modern value, and the difference between the Julian and true year
¹/₁₃₄ of a day. (The correct value is ¹/₁₂₈). Either of these figures
may have been known to Dante indirectly: perhaps he had obtained the
Alfonsine value in conversation with Brunetto Latini, who had visited
Alfonso’s court. His fraction was evidently only approximate, but it is
interesting to know that he had found out more than popular books could
tell him about the period of the sun’s revolution, and that he had been
sufficiently struck by the small difference between the calendar and
astronomical years to mention it in a picturesque way in his poem. It
is possible that he had heard of Roger Bacon’s appeal to the Pope in
1267 to correct the calendar because the date of the spring equinox was
of importance in connection with the observation of Easter.

It is hardly necessary to remind my readers that this was done by
another Pope three hundred years later, before January had made much
more advance towards becoming a spring month. The hundredth part of a
day, of which Beatrice complained, is now subtracted from the year by
omitting to make century years leap years; but as the error was really
not quite so great as she said, an exception is made for century years
divisible by 400. Thus 1600 was a leap year, but not 1700, 1800, or
1900.

[Illustration: Fig. 40. The Zodiac and the Months.]

Dante seems to have connected any season of the year with the sun’s
path in the zodiac as readily as with the name of a month. The sun’s
yearly course through the signs is shown diagrammatically in figure 40,
and a glance at this will make clear a number of allusions without any
explanation.

Starting from the first point of Aries at the spring equinox, which in
Dante’s time fell in the middle of March, and taking one-twelfth of
the year to traverse each sign, it is evident that during the end of
March and beginning of April the sun was in Aries; he entered Cancer
and reached the summer solstice in June, the autumnal equinox in Libra
in September, and the winter solstice when he entered Capricornus in
December. The six signs above the horizontal line are northern, the six
below are southern.

The following are a few typical examples.

When Dante wishes to express the transition of his feelings from
despondency to courage, at seeing the stern and troubled face of his
guide melt suddenly to a smile, he compares himself to a poor shepherd
who wakes early and sees the fields covered, as he thinks, with snow,
but in a short time finds that it is only hoar-frost which has put on
the semblance of her white sister, and seeing the face of the world
changed he gladly leads out his sheep to pasture. The time at which
this may happen is

    “Quella parte del giovinetto anno,
    Che il sole i crin sotto l’Aquario tempra,
    E già le notti al mezzodì sen vanno.”[225]

------------------------------------------------------------------------
[225]
    “In that part of the youthful year wherein
    The sun his locks beneath Aquarius tempers,
    And now the nights draw near to half the day.”
                         _Inf._ xxiv. 1-3. (_Longfellow_).
------------------------------------------------------------------------

That part of the youthful year when the sun cools his locks beneath
Aquarius is clearly the end of January or beginning of February, but
the last line may bear one of two meanings. If we translate “mezzodì”
as “half the day” it means that the nights are growing shorter, and
very soon (in March) when the sun will have reached the equinox, they
will be just twelve hours long. If we take “mezzodì” as meaning “the
south,” we must interpret the passage in the light of others in the
_Divine Comedy_ where Night is personified, and considered as circling
in the zodiac always opposite to the sun. For instance in _Purg._ ii.
1-6 (a passage which will be more fully explained later) Night is
described as circling opposite to the sun, “La notte, che opposita a
lui cerchia,”[226] and as the sun at that time was in Aries, Night was
in Libra, “le Bilance.” Henceforth for six months the sun will be in
the northern signs, and the days longer than the nights, but as soon as
Night begins to assert her supremacy, and the nights begin to be longer
than the days, the sun enters Libra and then it is not visible all
night. This is the meaning of

------------------------------------------------------------------------
[226] “Night that opposite to him revolves.” (_Longfellow_).

                                “le Bilance,
    Che le caggion di man quando soverchia.”[227]

[227]
    “The Scales, that from her hands are dropped
    When she reigns highest.”
                              _Purg._ ii. 5, 6. (_Carey_).
------------------------------------------------------------------------

When Night becomes dominant, the Scales fall from her hand, for the sun
is in that sign.

Applying this idea to the passage quoted above, it will mean “The
nights are going southward,” for the sun in Aquarius is not far from
the point where he crosses the equator to the north, therefore Night
circling opposite to him is nearing the point where she goes south.
Either interpretation is faithful to fact, but perhaps the circumstance
that the plural noun is used favours the first.

[Illustration: Fig. 41. The Ram on the Ecliptic. [_To face p. 279._

_From the “Cosmi Historia” of Robert Flud, a.d. 1612._

(_Reproduced from Brown’s Phainomena of Aratos._)]

Conrad Malaspina prophesied to Dante that his favourable opinion of the
Malaspina family would be justified “before the sun had come to rest
again seven times in the bed which the Ram covers and bestrides with
his four feet.”

    “Ed egli: Or va, che il Sol non si ricorca
    Sette volte nel letto che il Montone
    Con tutti e quattro i pie copre ed inforca
    Che cotesta cortese opinione ...”[228]

------------------------------------------------------------------------
[228]
    “And he: Now go, for the sun shall not lie
    Seven times upon the pillow which the Ram
    With all his four feet covers and bestrides.
    Before that such a courteous opinion ...”
                    _Purg._ viii. 133-136. (_Longfellow_).
------------------------------------------------------------------------

The sun was at the time in the Ram, and Malaspina means that less
than seven years would elapse, before his prophecy was fulfilled.
The aptness of the description may be seen by the figure of Aries
as portrayed in an old seventeenth century book in which the Ram is
uncomfortably trying to sit on the ecliptic.

Another instance is in the beautiful midwinter Ode, “Io son venuto al
punto della rota.”[229] Each stanza pictures a feature of a severe
winter—snow and rain, the absence of summer birds, bare trees and dead
flowers, the favourite walk become a torrent; but the first describes
the position of stars and planets. When the sun sets, the Twins
appear on the eastern horizon, hence we know at once that the sun is
in Sagittarius and the time is November or December. To confirm his
melancholy, the poet adds that the Star of Love (Venus) is hidden from
us by the sun’s rays which now shine athwart her, and that the planet
which strengthens the cold (Saturn, the “frigida stella” of Virgil)
displays himself in that arc of the sky in which all the seven planets
cast the shortest shadow;[230] that is, either he is on the meridian at
sunset, or he is in the most northerly part of the zodiac, in Gemini or
Cancer. A planet in this place, as for instance the sun at midsummer,
is visible longer, describes a longer arc, and casts shorter shadows,
than in any other part of the zodiac. And as this is the part which
rises over the eastern horizon as the sun sets, Saturn would also rise
at that time and remain visible all night.

------------------------------------------------------------------------
[229] “I have come to that part of the wheel.” _Canz._ xv.

[230] Like all mediæval writers, Dante includes the sun and moon among
the seven planets. The others do not cast perceptible shadows, except
Venus and Jupiter at their brightest.

The opening lines of the Ode run thus:—

    “Io son venuto al punto della rota,
    Che l’orizzonte, quando il Sol si corca,
    Ci parturisce il geminato cielo;
    E la stella d’amor ci sta rimota
    Per lo raggio lucente, che la ’nforca
    Sì di traverso, che le si fa velo;
    E quel pianeta che conforta il gelo
    Si mostra tutto a noi per lo grand’ arco,
    Nel qual ciascun de’ sette fa poca ombra.”[231]

[231]
    “I to that point in the great wheel have come,
    Wherein the horizon, when the sun doth set,
    Brings forth the twin-starred heaven to our sight;
    And Love’s fair star away from us doth roam,
    Through the bright rays obliquely on it met
    In such wise that they veil its tender light;
    That planet which makes keen the cold of night
    Shows himself to us in the circle great,
    Where each star of the seven casts little shade.”
                                   (_Plumptre_).
------------------------------------------------------------------------

It is astonishing that Giuliani should so completely miss the point of
the “twinned sky,” that he substitutes “ingemmato” for “geminato,” and
reads—

                               “ ... la rota,
    Ch’ all orizzonte, quando il Sol si corca,
       Ci parturisce l’ingemmato cielo.”[232]

------------------------------------------------------------------------
[232] “The Wheel which, when the sun sets, brings forth for us on the
horizon the jewelled sky.”
------------------------------------------------------------------------

He understands the hour of evening to be meant, when the Wheel of
Day and Night brings a jewelled, _i.e._ starry sky on the horizon as
the sun sets. But it is not only on the horizon that stars appear at
sunset; and the mention of Gemini to indicate the time of year is
thoroughly characteristic of Dante. The Wheel is the revolving year
which has carried the sun into Sagittarius.

Angelitti remarks that the whole description was literally true for
December 1296, since Venus was then in conjunction with the sun, and
Saturn in Cancer;[233] and as this poem is a complaint of the hardness
of his lady, to whom the poet is nevertheless wholly devoted, it may
well have been written in that time when the lady Philosophy refused to
smile upon her lover.[234]

------------------------------------------------------------------------
[233] _Sulla Data del Viaggio Dantesco_ p. 90, note.

[234] Comparing _Conv._ II. ii. 12, xiii. 49-52, and IV. i. 60-62, we
learn that in August 1293 (_vide infra_, p. 314), Dante first became
acquainted with the Lady Philosophy; that in the early part of 1296 he
was completely under her spell; and that some time afterwards she for a
while estranged herself from him.
------------------------------------------------------------------------

Further on in the same poem the effects of the sun in spring, when he
is in the sign of Aries, are alluded to as “the virtue of Aries”:—

    “Passato hanno lor termine le fronde,
     Che trasse fuor la virtù d’Ariete,
     Per adornare il mondo, e morta è l’ erba.”[235]

------------------------------------------------------------------------
[235]
    “Scattered and faded now is all the foliage
    Which had burst forth, beneath the power of Aries,
    To beautify the world, the grass is withered.”    _Canz._ xv. 40-42.
------------------------------------------------------------------------

Contrast with this the passage in the _Paradiso_ where “nocturnal
Aries” is used as a synonym for autumn.

    “Questa primavera sempiterna
     Che notturno Ariete non dispoglia.”[236]

------------------------------------------------------------------------
[236]
    “This everlasting spring
    Nocturnal Aries never can despoil.”
                                _Par._ xxviii. 116-117.
------------------------------------------------------------------------

For although Aries may be seen during some part of the night in the
greater part of the year, it is most emphatically a noctural sign when
it rises as the sun sets, and remains above the horizon until he rises;
this happens when the sun is in the opposite sign of Libra, which he
enters at the autumnal equinox.

A rather curious passage in the _Paradiso_ is incomprehensible unless
we think of the sun’s path in the zodiac, and realize that Dante is
comparing the brightness of the spirit of St. John in an indirect way
with the brightness of the sun.

    “Poscia tra esse un lume si schiarì,
    Sì che, se il Cancro avesse un tal cristallo,
    L’inverno avrebbe un mese d’un sol dì.”[237]

------------------------------------------------------------------------
[237]
    “Thereafterward a light among them brightened
    So, that if Cancer one such crystal had
    Winter would have a month of one sole day.”
                     _Par._ xxv. 100-102. (_Longfellow_).
------------------------------------------------------------------------

If a light as dazzling as this spirit were to shine forth in Cancer,
there would be perpetual day for a whole month in winter. For when the
sun entered Capricornus, which he does in December, he would be exactly
opposite, so that as one light set the other would rise, and there
would be no darkness until the sun passed into another sign.

To many similar instances the diagram (p. 276) will be found to supply
a key, and some we shall have occasion to notice presently in another
connection.


3. THE STARS.

If our poet did not love moonlight, there is no doubt that starlight
was very dear to him. Never are stars spoken of as cold, or placed in
antithesis to the sun. Rather are they classed together, as in the
pathetic letter, written when he heard of the possibility that the
Florentines might receive him again if he would consent to return as a
disgraced but pardoned criminal. If this is the only path to Florence,
never will he re-enter the beloved city. “What then?” he cries. “Can he
not see the mirrors of the sun and of the stars, wherever he may be?
can he not meditate on precious truths under any sky?”[238]

------------------------------------------------------------------------
[238] _Ep._ ix. 46-49.
------------------------------------------------------------------------

He describes the Inferno as bereft of stars as well as of sun;[239]
he hopes to escape those dark abysses to see the beautiful stars
again,[240] and the terror of the sounds of weeping and crying is
heightened indescribably by the simple words:—“risonavan per l’aer
senza stelle.”[241] When he does at length come forth to see “le cose
belle che porta il ciel”[242] how eagerly he gazes, not only at Venus,
but at the new stars in the south! how his “greedy eyes”[243] seek
the same region as soon as dusk begins to fall! and how radiantly the
stars look down upon him on that last night on the rocky slopes of the
Mountain, near the summit![244]

------------------------------------------------------------------------
[239] _Inf._ iii. 23.

[240] _Inf._ xvi. 82, 83.

[241] “Resounded through the air without a star.” _Inf._ iii. 23.

[242] “The fair things that heaven holds.” _Inf._ xxxiv. 137, 138.

[243] _Purg._ viii. 85.

[244] _Purg._ xxvii. 89, 90.
------------------------------------------------------------------------

This is all allegorical, no doubt, but it is because of Dante’s
feeling for the real “belle stelle”[245] that he uses them as symbols
of truth and holiness, and concludes each Cantica of the _Divine
Comedy_ with their name:—

------------------------------------------------------------------------
[245] “Beautiful stars,” _Inf._ xvi. 83.

    “E quindi uscimmo a riveder le stelle.”[246]
    “Puro e disposto a salire alle stelle.”[247]
    “L’Amor che move il sole e l’altre stelle.”[248]

[246] “Thence issuing we beheld again the stars.”

[247] “Pure and disposed to mount unto the stars.”

[248] “The Love that moves the sun and the other stars.”
------------------------------------------------------------------------

Here “stelle” has the wider meaning of the French “astres,” for which
we have no equivalent in English except the clumsy “heavenly bodies;”
but most of Dante’s hundred references are to stars in the more special
sense, and often to particular stars or constellations. Over eighty
occur in the _Divine Comedy_.

Stars are jewels, torches, flames, immortal nymphs adorning every
region of the sky.[249] Heaven is made beautiful by their light, and
the joy of the angels is expressed in their shining, as mortal joy
shines forth in human eyes.[250] If the spirits in the fourth heaven
are described as glowing suns,[251] the “splendours” that descend upon
the golden ladder in the seventh, make Dante think that all the stars
in the sky are gathered together there.[252]

------------------------------------------------------------------------
[249] _Purg._ ix. 4; _Purg._ viii. 89; _Purg._ i. 25; _Par._ xxiii. 26.

[250] _Par._ ii. 130, 142-144.

[251] _Par._ x. 76.

[252] _Par._ xxi. 28-33.
------------------------------------------------------------------------

The eyes of Beatrice shone brighter than stars;[253] light comes as
from many stars in reading the sacred books;[254] faith gleams like a
star in the sky;[255] and truth appears in a mind cleared of falsehood
and error like the radiance of stars in a sky which has been wholly
swept of cloud and mist by a north wind.

------------------------------------------------------------------------
[253] _Inf._ ii. 55.

[254] _Par._ xxv. 70. See also _Conv._ II. xvi. 4-12, where the
writings of Boëthius and Cicero, and all instructive books, are called
stars full of light.

[255] _Par._ xxiv. 147.

    “Come rimane splendido e sereno
        L’emisperio dell’ aer, quando soffia
        Borea da quella guancia ond’ è più leno,
    Perchè si purga e risolve la roffia
        Che pria turbava, sì che il ciel ne ride
        Con le bellezze d’ogni sua paroffia:
    Così fec’ io, poi che mi provvide
        La Donna mia del suo risponder chiaro,
        E come stella in cielo il ver si vide.”[256]

[256]
    “Even as remaineth splendid and serene
        The hemisphere of air, when Boreas
        Is blowing from that cheek where he is mildest,
    Because is purified and resolved the wrack
        That erst disturbed it, till the welkin laughs
        With all the beauties of its pageantry:
    Thus did I likewise, after that my Lady
        Had me provided with her clear response,
        And like a star in heaven the truth was seen.”
                       _Par._ xxviii. 79-87. (_Longfellow_).
------------------------------------------------------------------------

Stars, as well as the sun, are used as symbols for the objects of
Dante’s deepest reverence; for the Blessed Virgin is called “la viva
stella,”[257] and the Final Vision in which the redeemed find their
ultimate bliss is a Trinal Light seen as a single star:—

------------------------------------------------------------------------
[257] “The shining star.” _Par._ xxiii. 92.

    “O trina Luce, che in unica stella
          Scintillando a lor vista sì gli appaga,
          Guarda quaggiù alla nostra procella.”[258]

[258]
    “O Trinal Light, that in a single star
        Sparkling upon their sight so satisfies them,
        Look down upon our tempest here below!”
                        _Par._ xxxi. 28-30. (_Longfellow_).
------------------------------------------------------------------------

The diurnal motion of the stars is referred to many times. As Dante
watched the mystical procession in the Earthly Paradise, and saw one
group follow in the footsteps of another across the flowers and the
grass, he thought of the stately procession of stars which we see here
by night, star following star across the sky.[259] Their movement marks
for him the passage of time, as we see in the first sonnet of the _Vita
Nuova_:—

------------------------------------------------------------------------
[259] _Purg._ xxix. 91.

    “Già eran quasi ch’ atterzate l’ ore
    Del tempo che ogni stella è piu lucente.”[260]

[260]
    “Of those long hours wherein the stars above
      Wake and keep watch, the third was almost nought.”
                        _V. N._ iii. 81, 82. (_Rossetti_).
------------------------------------------------------------------------

and in the _Inferno_, where Virgil hastens Dante, saying that all
the stars are sinking which were rising when he started on his long
journey.[261]

------------------------------------------------------------------------
[261] _Inf._ vii. 98, 99.
------------------------------------------------------------------------

The motion of those stars which neither rise nor set, but are always
seen circling round the pole, is clearly described. In the heaven
of the sun, spirits gather round Dante and Beatrice, and circle
round them, “Come stelle vicine ai fermi poli;”[262] and the motion
of the stars near the pole is said to be slow, like the part of a
wheel which is near the axle.[263] We may compare these descriptions
with the statement of Alfraganus:—“Eæ stellæ (_i.e._ the northern
circumpolar) vertuntur omnes circa idem punctum. Et quei ex iis
puncto huic est vicinior, minorem conficit circulum: motusque ejus
appâret lentior.”[264] Dante assumes that his readers understand this
motion when he describes himself as seeing unknown stars near the
South Pole. The Mount of Purgatory is supposed to be situated in the
southern hemisphere, and at his first arrival, before dawn, he turns
to the right, after looking at Venus in the east, therefore to the
south, and sees near the pole four stars so brilliant that the whole
sky seems to rejoice in their radiance, and he pities the “widowed”
northern hemisphere because they are invisible there.[265] In the
evening, as soon as it begins to grow dark, although he is engaged
in an interesting discourse with a friend with whom he had exchanged
warm greetings, he looks eagerly once more towards the pole (note the
intensity expressed by the repeated “pure”)—

------------------------------------------------------------------------
[262]

    “Like unto stars neighbouring the stedfast poles.”
                                      _Par._ x. 78.

[263] _Purg._ viii, 86, 87.

[264] “These stars all revolve round the same point, and the nearer a
star is to this point, the smaller is the circle that it makes, and the
slower its motion appears.” _El. Ast._ cap. ii.

[265] _Purg._ i. 22-27.

    “Gli occhi miei ghiotti andavan pure al cielo,
        Pur là dove le stelle son più tarde,
        Sì come rota più presso allo stelo.”[266]

[266]
                          “My insatiate eyes
    Meanwhile to heaven had travelled, even there
    Where the bright stars are slowest, as a wheel
    Nearest the axle.”
                     _Purg._ viii. 85-87. (_Carey_).

He now sees three bright stars which make this pole glow with light,
and Virgil says that the stars he saw in the morning are low, while
those now visible have risen higher to take their place.

    “Ed egli a me: Le quattro chiare stelle
        Che vedevi staman son di là basse,
        E queste son salite ov’ eran quelle.”[267]

[267]
    “And he to me: The four resplendent stars
        Thou sawest this morning are down yonder low,
        And these have mounted up to where those were.”
                       _Purg._ viii. 91-93. (_Longfellow_).
------------------------------------------------------------------------

The diurnal movement of the starry heaven is also alluded to in the
_Convivio_, and contrasted with that immensely slow movement which was
discovered by Hipparchus, and is called by us Precession. The starry
heaven, says Dante, displays one of its poles to us, and keeps the
other hidden; and in like manner it displays only one movement to us,
and keeps the other almost hidden. By the first, it revolves once in
every day from east to west; the other is nearly insensible, being only
one degree in a hundred years, and it is from west to east.[268] This
is the value of precession as given by Alfraganus, following Ptolemy.

------------------------------------------------------------------------
[268] _Conv._ II. xv. 10-14, and 96-104.
------------------------------------------------------------------------

It was this stupendous and mysterious cycle which was used by Dante
to measure the age of Beatrice, though for his own he used (as we
saw) the ordinary measure of the sun’s period. When he first saw “la
gloriosa donna”[269] she had only been in this life so long that the
starry heaven had moved towards the east one-twelfth part of a degree.
Therefore, she was one-twelfth of a hundred years old, or 8 years 4
months, “so that it was near the beginning of her ninth year that she
appeared to me, and I saw her nearly at the end of my ninth.”[270]

------------------------------------------------------------------------
[269] “The glorious Lady.”

[270] _V. N._ ii. 9-15.
------------------------------------------------------------------------

Dante tells us how many stars had been counted by “the sages of Egypt,”
by whom he means Ptolemy and the other Alexandrians: he did not know
that the star catalogue of the _Almagest_ was originally made by
Hipparchus of Rhodes.

    “Dico ch’ il cielo stellato ci mostra molto stelle;
    chè, secondochè li savi d’Egitto hanno veduto,
    infino all’ultima stella che appare loro in
    meridie, mille ventidue corpora di stelle pongono,
    di cui io parlo.”[271]

------------------------------------------------------------------------
[271]
    “I say that the starry heaven displays a multitude
    of stars to us, for as the Sages of Egypt have
    perceived, including the last star which appears
    to them in the south, they reckon one thousand
    and twenty-two starry bodies, of which I am now
    speaking.”
          _Conv._ II. xv. 18-22. (_Jackson_).
------------------------------------------------------------------------

It will be noted that he carefully avoids saying that this is the
number of all the stars visible from the whole earth. Had he, like
Ristoro, run away with the idea that a blank space on the globe meant
a blank in the sky, his night sky seen from Purgatory would have been
strangely bare and dull! Yet both writers used the same text-book.
Dante is here following Alfraganus closely, for he had written in his
nineteenth chapter:—

    “Sciendum itaque sapientes inivisse mensuram
    stellarum fixarum omnium, quoad instrumentis
    observari eæ potuerunt, extremam usque meridiei
    partem, in tertio climate ipsis conspicuam....
    Stellæ universae quarum agi mensura potuit sunt
    mille viginti duæ.”[272]

------------------------------------------------------------------------
[272] “You are to know that the Sages measured the places of all the
fixed stars as accurately as possible with their instruments, as far
south as they could see in the third climate.... The number of all the
stars which he was able to measure is one thousand and twenty-two.”
------------------------------------------------------------------------

Both in the _Quæstio_ and the _Paradiso_ Dante notes how stars differ,
not only in their brightness or “magnitude,” but also in the quality of
their light, by which he probably means their colour:—

    “Videmus in eo [_sc._ cœlum stellatum] differentiam
    in magnitudine stellarum et in luce.”[273]

------------------------------------------------------------------------
[273] “We see in it (the starry heaven) a difference in the magnitude
of the stars and in their light.” _Qu._ xxi. 19-21.

    “Lumi, li quali nel quale e nel quanto
     Notar si posson di diversi volti.”[274]

[274]
    “Lights many the eighth sphere displays to you
    Which in their quality and quantity
    May noted be of aspects different.”
                         _Par._ ii. 65-66. (_Longfellow_).
------------------------------------------------------------------------

It seems as if it were the beauty and the movement of the starry sky
as a whole which appealed to Dante, rather than the distinguishing of
special stars and constellations. Those which he mentions are almost
all either in the zodiac, and used to denote the hour, the season, or
the position of one of the seven planets; or else they are near one of
the poles and illustrate the circumpolar motion.

All the zodiacal constellations are mentioned except Virgo and
Sagittarius. Besides the ordinary names of “Ariete,” “Libra,” etc.,
Aries is called “il Montone;”[275] Gemini “il segno che segue il
Tauro,” “gli eterni Gemelli,” and “il bel nido di Leda,”[276] in
reference to the mother of Castor and Pollux, its two brightest
stars; Libra is “le Bilance”;[277] Scorpio “il freddo animale”;[278]
Capricornus is “il Capra del ciel”;[279] and Pisces “la celeste
Lasca.”[280]

------------------------------------------------------------------------
[275] “The Ram.” _Purg._ viii. 134; _Par._ xxix. 2.

[276] “The sign which follows Taurus,” _Par._ xxii. 110, 111; “The
eternal Twins,” xxii. 152; “The fair nest of Leda,” xxvii. 98.

[277] “The Balance.” _Purg._ ii. 5.

[278] “The cold creature.” _Purg._ ix. 5.

[279] “The Goat of the sky.” _Par._ xxvii. 69.

[280] “The celestial Carp.” _Purg._ xxxii. 54.
------------------------------------------------------------------------

In one place Castor and Pollux are mentioned, but merely as a synonym
for the whole constellation of Gemini.[281] “Il petto del Leone
ardente”[282] is perhaps Cor Leonis, the Heart of the Lion, for this is
the name given to Regulus by both Ptolemy and Alfraganus. The “Maggior
Fortuna”[283] of _Purg._ xix. 4, is a group of stars belonging to the
two constellations of Aquarius and Pisces, in which the geomancers, who
told fortunes by means of certain points traced at random, thought they
saw a special series of these points,-:::..

------------------------------------------------------------------------
[281] _Purg._ iv. 61.

[282] “The burning Lion’s breast.” _Par._ xxi. 14.

[283] “Greater Fortune.”
------------------------------------------------------------------------

It is generally agreed that the “gemme” of _Purg._ ix. 4, “poste in
figura del freddo animale, Che con la coda percote la gente,”[284] are
some stars of Scorpio which were shining on the eastern horizon just
before the moon rose on the first night in the Island of Purgatory.

------------------------------------------------------------------------
[284]
    “Gems ... set in the shape of that cold animal
       Which with its tail doth smite amain the nations.”
                                              (_Longfellow_).
------------------------------------------------------------------------

The zodiacal constellations in general are spoken of as “all the
lights of his [the sun’s] path:” “Tutti i lumi della sua strada.”
(_Par._ xxvi. 121, 122).

The pole star is described as the point of the axle round which the
first sphere revolves.[285] The first sphere (or wheel, as it is
called, with reference to its circling motion) is here the Primum
Mobile, which was thought to cause the diurnal motion. This unique
position gains for the pole star the name of “the star,” as for
instance in _Conv._ III. v. 84, 85, where Dante says that a man
standing at the north pole would have “la stella” directly over his
head. And in Paradise he hears a voice among the spirits which makes
him turn in its direction as the needle turns to the star—

------------------------------------------------------------------------
[285] _Par._ xiii. 11, 12.

              “Voce, che l’ago alla stella
    Parer mi fece in volgermi al suo dove.”[286]

[286]
                                “A voice,
    That made me seem like needle to the star,
    In turning to its whereabout.”
                     _Par._ xii. 29, 30.  (_Carey_).
------------------------------------------------------------------------

This property of the magnet was known in Dante’s day, as well as its
power of attracting iron, though only the latter had been known to
Ptolemy and the classical world. Whether the discovery came from China,
where it is said that some form of compass has been used since the
second century A.D., or whether it had been discovered independently
by Arab or Italian navigators, we do not know: but scholars and poets
in the twelfth and early thirteenth centuries write of the “ugly brown
stone” used by sailors to make an instrument that cannot lie. For a
needle, rubbed by it and run through a straw, when floated on water
turns so surely to “the star” that one need never doubt its guidance.
Thus writes Guyot, the poet of Languedoc, about 1200:—

    “Un art font qui mentir ne puet,
    Par la vertu de la manete,
    Une pierre laide et brunete,
    Ou le fers volentiers se joint,
    Ont: si esgardent le droit point,
    Puis c’une aiguile i ont touchie,
    Et en un festu l’ont couchie,
    En l’eve la metent sanz plus,

       *       *       *       *       *

    Puis se torne la pointe toute
    Contre l’estoile si sanz doute,
    Que ja nas hom n’en doutera.”

And thus Ristoro:—

    “L’angola, che guidi li marinari, chè per la virtu
    del cielo è tratta e rivolta alla stella la quale è
    chiamata tramontana.”[287]

------------------------------------------------------------------------
[287] “The needle which guides mariners, for by the virtue of the
heavens it is attracted and turned towards that star which is called
the North Star.” _Composizione del Mondo_, Bk. VII. part iv. ch. 2.
------------------------------------------------------------------------

Albertus Magnus speaks of it in the same way, as something well known
to mariners.

It seems strange to us how Dante and his contemporaries failed to see
the importance of this discovery; Brunetto Latini, when the ugly stone
was shown to him on his visit to Roger Bacon at Oxford, even professing
to regard it as a mere toy, of no practical use. Dante discusses the
number of the stars known to Ptolemy, and describes the last mad voyage
of Ulysses, who saw all the stars of the other pole, while ours sank
low on the ocean floor;[288] but he does not seem to guess that the new
toy would make possible even longer voyages than these, and that in
time the blank in his celestial globe would be filled.

------------------------------------------------------------------------
[288] _Inf._ xxvi. 127-129.
------------------------------------------------------------------------

Yet even in his own life-time plucky little Genoa fitted out two
galleys which ventured through the forbidden Straits, with intent to
circumnavigate Africa and find a new route to India. And meanwhile,
travelling by old overland or coasting routes, Italian missionary
monks, and Italian traders, were visiting southern countries and
describing southern skies. Friar Giovanni de Monte Corvino, who was
in South India with Nicolo of Pistoia, writes home in 1291, telling
of his disappointment that he had never been able to see “the other
pole star” (l’altra tramontana), though he saw new stars moving round
and evidently near to it, close to the southern horizon. A few years
later Marco Polo the Venetian was dictating the story of his travels to
a Pisan in Genoa: he had been further south than the missionaries, for
in a certain island (probably Sumatra) he had seen the south pole “a
spear’s length” above the horizon; and in the land of Zinzi (Zanzibar?)
he had seen a marvellous star as big as a sack (which was evidently the
Greater Magellanic Cloud). This he drew a picture of with his own hand.

Dante’s silence, and probable incredulity, regarding these experiences
of his own countrymen and contemporaries is characteristic of his
age; for scholars were too eager to explore the precious classical
lore lately recovered from oblivion, to realize that they were on the
threshold of a new era in knowledge, of which these men were pioneers.

It is sometimes thought, however, that Dante made use of contemporary
observations of southern skies in his description of the stars he
feigned himself to have seen when the Wain disappeared under his
northern horizon.[289] Quite correctly, he does not place any single
bright star to mark the south pole; his two constellations, one of four
bright stars seen above the pole in the morning,[290] one of three
which takes its place after sunset,[291] are these real or fictitious?

------------------------------------------------------------------------
[289] _Purg._ i. 30.

[290] _Purg._ i. 26.

[291] _Purg._ viii. 89.
------------------------------------------------------------------------

It is a fact that there are four bright stars in the form of a cross,
lying between 56° and 63° south: are these Dante’s “quattro chiare
stelle,” “quattro luci sante?”[292] They were not recognized as a
separate constellation until the beginning of the sixteenth century,
when Amerigo Vespucci described them in his letters about his southern
voyages, and the Florentine Andrea Corsali wrote about the marvellous
Cross which was so beautiful that in his opinion no other constellation
in the sky was worthy to be compared with it. This, he believed, was
the very cross of which Dante had spoken in a prophecy.

------------------------------------------------------------------------
[292] “Four bright stars, four sacred lights.”
------------------------------------------------------------------------

Even among Dante’s most enthusiastic admirers, I suppose none will be
found to-day to support this view; but many think that he must have
heard of the Cross from travellers. True, these stars are visible
during at least part of the year in all places south of 34° north, and
therefore in North Africa, and they had been catalogued by Ptolemy as
part of the Centaur, so that no astronomer could take them to be a
newly-found constellation, but might not some unscientific traveller
like Marco Polo have brought a vague report of their position?

[Illustration: MAP OF STARS VISIBLE BEFORE DAWN IN PURGATORY. _To face
p. 295_]

To this we might reply that Dante never says his four stars were in
the form of a Cross; that there had to be four to represent the four
Pagan virtues, the other constellation of three representing the three
Christian virtues (compare the group of four handmaidens who sing, “Noi
siam qui ninfe, e nel ciel siamo stelle,”[293] and are followed by a
group of three);[294] and that this other constellation was certainly
imaginary, since there is no group of three bright stars anywhere near
the south pole.

------------------------------------------------------------------------
[293]
    “We are nymphs here, and in heaven we are stars.”
                                     _Purg._ xxxi. 104-106.

[294] _Purg._ xxxi. 111.
------------------------------------------------------------------------

But the fact is that conjectures and arguments are unnecessary, since
Dante has expressly said that his four stars had never been seen before
by anyone except the first people—“non viste mai fuor che alla prima
gente,” (_Purg._ i. 24)—that is, our first parents, in that Eden of his
imagining which was in the southern hemisphere, and on the island where
he was then standing in his vision.

As a matter of curiosity I have included a map showing what stars
would have been really visible to Dante at the supposed latitude of
Purgatory, when Pisces was on the eastern horizon, as described in
_Purg._ i. It will be seen that the Southern Cross is low, and would
have been hidden behind the Mountain of Purgatory at five o’clock in
the morning.[295]

------------------------------------------------------------------------
[295] Antonelli thinks the four stars were α and β Crucis, α and β
Centauri, all of which had been mentioned by Ptolemy, and all lie
near the circle which marks the limit of circumpolar stars in the
supposed latitude of Purgatory (32° south). The three stars he says
were ζ Navis, Canopus, and Achernar:—Antonelli, _Accenni alle Dottrine
Astronomiche nella Divina Commedia_.
------------------------------------------------------------------------

Among northern constellations, Ursa Major is frequently spoken of by
Dante, under different names, but always with reference to its high
northern latitude. As the Wain, “il Carro,” it is said to be lying
in the north-west when Pisces is on the eastern horizon, and to have
disappeared from view in the southern hemisphere.[296] The wain-pole
or shaft is pictured as sweeping round in the diurnal revolution,
but always remaining above our horizon day and night, throughout its
turning:

------------------------------------------------------------------------
[296] _Inf._ xi. 113, 114; _Purg._ i. 30.

                “Quel Carro, a cui il seno
    Basta del nostro cielo e notte e giorno,
    Sì ch’ al volger del temo non vien meno.”[297]

[297]
    “The Wain, that in the bosom of our sky
     Spins ever on its axle, night and day.”
                           _Par._ xiii. 7-9.  (_Carey_).
------------------------------------------------------------------------

The same idea is expressed in the Midwinter Ode, where the
constellation is called the Seven Frosty Stars, never lost to sight in
Europe:—

    “Fuggito è ogni augel che ’l caldo segue
     Dal paese d’Europa, che non perde
     Le sette stelle gelide unquemai.”[298]

------------------------------------------------------------------------
[298]
    “Fled is every bird that seeks the warmth,
    From European lands which never lose
    The seven cold stars.”
                          _Canz._ xv. 27-29.
------------------------------------------------------------------------

This is a reminiscence of some lines of Boëthius quoted by Dante in
_De Monarchia_, in which the northern nations are described as under
the sway of the “septem gelidi triones.”[299] The Septem Triones, the
Seven Ploughing Oxen, was one of the Latin names for Ursa Major, whence
comes “septentrional” for North. This name also is used by Dante in
_Purg._ xxx. 1, where the Seven Candlesticks of the mystic procession
seen in the Garden of Eden are likened to these seven stars, and are
named the Septentrion of the First Heaven (the Empyrean). This divine
Septentrion was guiding the Procession, as the starry Septentrion of a
lower heaven guides the mariner into port:

------------------------------------------------------------------------
[299]
    “Seven cold oxen.”
                _De Mon._ II. ix. 96.

              “faceva lì ciascuno accorto
    Di suo dover, come il più basso face
    Qual timon gira per venire a porto.”[300]

[300]
                        “To duty there
    Each one convoying, as that lower doth
    The steersman to his port.”
                        _Purg._ xxx. 4-6.  (_Carey_).
------------------------------------------------------------------------

Like the seven stars, also, the heavenly Septentrion is said
figuratively to know neither setting nor rising, but unlike them it
knows no cloud except of sin.[301] Because it is spoken of as guiding
mariners, some commentators have taken the above to refer rather to
Septentrio Minor (Ursa Minor), which also has seven chief stars, and
is a better guide because nearer the Pole, as Thales taught; but the
comparatively faint stars of the Little Bear would not be so apt a
comparison with the celestial lights.

------------------------------------------------------------------------
[301] _Purg._ xxx. 1-3.
------------------------------------------------------------------------

By the name of the Bears, both Ursa Major and Minor are referred to as
guides at sea in _Par._ ii. 9. In the strange new seas on which Dante
warns his readers he is about to enter, Minerva will blow a favouring
wind, Apollo will steer the barque, and the nine Muses will guide his
course by the Bears. They are also spoken of together in _Purg._ iv.
65, to indicate the northern part of the sky.

A fifth name for Ursa Major is derived from the fable (known to Dante
probably from Ovid’s _Metamorphoses_) of the nymph Helice, who was
turned into a she-bear by Juno, and was hunted by her own son, Orcas.
Jupiter transformed them into Ursa Major and Boötes.

    “Se i barbari, venendo di tal plaga
       Che ciascun giorno d’Elice si copra,
       Rotante col suo figlio ond’ ell’ è vaga,
     Vedendo Rome e l’ ardua sua opra,
       Stupefaciensi....”[302]

------------------------------------------------------------------------
[302]
    “If the barbarians coming from some region
      That every day by Helice is covered,
      Revolving with her son whom she delights in,
    Beholding Rome and all her noble works
      Were wonder-struck....”
                        _Par._ xxxi. 31-35. (_Longfellow_).
------------------------------------------------------------------------

Here we have the same idea as of the Wain wheeling round but never
setting, with the addition of a neighbouring constellation describing a
circle in the same time.

The Barbarians who lived in a region always dominated by Ursa Major,
and came to marvel at the mighty buildings of ancient Rome, are
probably the races of northern Europe in general; and this reminds
us again of the lines of Boëthius quoted above, for it is among the
peoples ruled by Rome that he mentions “quos premunt septem gelidi
triones.”[303] If, however, Dante meant a country where the seven stars
pass exactly overhead, the barbarians must have inhabited Scotland, or
southern Scandinavia, or central Russia. If he means that Boötes also
remained always above the horizon, they must have come from within the
Arctic Circle, but this is not likely.

------------------------------------------------------------------------
[303] “Those under the sway of the seven cold oxen.”
------------------------------------------------------------------------

[Illustration: Fig. 42. Ursa Minor as a Horn. _Par._ xiii. 10.]

In one of the passages just quoted other constellations and stars are
mentioned together with Ursa Major. In _Par._ xii. Dante has compared
the two circles of spirits which surround Beatrice and himself to a
double rainbow, and to two garlands of immortal roses. In the next
canto he finds a new simile: in imagination he takes some of the
brightest and most familiar stars from our sky, and makes of them two
new constellations in the form of two crowns. The stars are these:
fifteen from different parts of the sky, which are so brilliant that
they shine through air dense enough to quench lesser orbs; the Wain,
which never sets in our sky; and the mouth of the horn whose tip is
the axis on which the Primum Mobile revolves. That is to say, as we
have before remarked, Dante takes the fifteen first-magnitude stars and
the stars instanced by Alfraganus as of second magnitude. Ursa Minor
is aptly compared to a horn, the wide mouth of which is formed by its
two bright stars Beta and Gamma,[304] while the narrow end is Alpha,
the Pole Star. These twenty-four bright stars we must then imagine to
group themselves into two constellations like that into which Ariadne,
the daughter of Minos, was changed when she died; this is Corona
Borealis or the Northern Crown, otherwise called Ariadne’s Crown,
which suggests a circle, though it is not a perfect one. Dante uses the
word “segni” for any constellations, a custom we find in Ristoro also,
although the modern usage is to restrict “signs” to mean only divisions
of the zodiac.

------------------------------------------------------------------------
[304] I do not know whether this comparison originated with Dante, but
it was well known to Spanish sailors two centuries later. In the _Arte
of Navigation_ which was “Englished out of the Spanyshe,” by Richard
Eden in 1561, Beta and Gamma of Ursa Minor are referred to as “two
starres called the Guardians, or the mouth of the horne.”
------------------------------------------------------------------------

The star-like spirits, thus grouped into a surpassingly brilliant
double constellation, begin to sing their ineffable heavenly song, and
to circle round the centre where Dante stands, in a marvellous dance,
whose swiftness, when compared with anything known on earth, is as the
movement of that swift heaven which carries with it all the rest, when
compared with the flowing of the sluggish river Chiana.[305]

------------------------------------------------------------------------
[305] _Par._ xiii. 1-28.
------------------------------------------------------------------------

This passage helps us to understand expressions which often strike
one as very strange, describing the circling movements of the spirits
in Paradise. For the likeness to stars is clear throughout. Their
brightness is an expression of their happiness,[306] and increases in
each succeeding heaven. Only in the lowest can Dante see the forms and
features of Piccarda and the other blessed spirits; in the next they
clothe themselves in light, and although at first the radiant eyes of
Justinian are seen, the first words addressed to him cause him to shine
more brilliantly than before, and as the sun conceals himself by his
own light, so the spirit conceals himself by the splendour which grows
with his joy.[307] In the third heaven the spirits shine in the star
of Venus like sparks seen in flame;[308] in the fourth they are called
suns, and surpass the sun in brilliancy;[309] in the fifth they are
compared with the Galaxy[310] and with shooting stars,[311] in the
seventh and eighth with stars[312] and with spheres of light, turning
on fixed poles and flaming like comets.[313]

------------------------------------------------------------------------
[306] _Par._ viii. 52, 53.

[307] _Par._ v. 136, 137.

[308] _Par._ viii. 16.

[309] _Par._ x. 76, 40-42.

[310] _Par._ xiv. 97-101.

[311] _Par._ xv. 13, 14.

[312] _Par._ xxi. 32, 33; xxiii. 26, 27.

[313] _Par._ xxii 23; xxiv. 11, 12.
------------------------------------------------------------------------

In like manner the swiftness of their motion increases in proportion
to the clearness with which each beholds eternal truth.[314] The
almost incredible speed with which Dante himself soars from sphere to
sphere, and with which the spirits move—whether in coming towards him,
impelled by Divine charity, in returning to the heaven of heavens,
or in circling with one another in mystic dance—is frequently dwelt
upon, and illustrated by many striking similes. The dance is always a
circling or wheeling movement (“il giro,” “la rota,” _Par._ viii. 20
and 26; ix. 65). And besides this, individual spirits turn with a rapid
motion, remaining on the same spot. Descending the celestial Ladder in
the heaven of Saturn, step by step, they revolve:—

------------------------------------------------------------------------
[314] _Par._ viii. 20, 21; and xxviii. 100-102.

                  “Vid’ io più fiamelle
    Di grado in grado scendere e girarsi,
    Ed ogni giro le facea più belle.”[315]

[315]
                    “Saw I many little flames
    From step to step descending and revolving,
    And every revolution made them fairer.”
                     _Par._ xxi. 136-138.  (_Longfellow_).

Compare 80, 81 and 39; and _Par._ xxiv. 10, 11.
------------------------------------------------------------------------

Now these two things, their light and their movements, were all the
facts concerning the stars which mediæval astronomers could observe;
and the movements were thought to be in circles and inconceivably
rapid. Motion in circles, and especially the movement of rotation
on an axis, remaining in the same place, had been said by Aristotle
to be the most noble form of motion, and the fittest for celestial
bodies. Therefore, when Dante represents the redeemed and the angels
as expressing their bliss by radiance and marvellously rapid motion
in circles, he makes them resemble the heavenly spheres and stars
among which they manifest themselves to him. The motions are directly
compared with those of stars in the passage already quoted:—

    “Poi, sì cantando, quegli ardenti soli
        Si fur girati intorno a noi tre volte,
        Come stelle vicine ai fermi poli.”[316]

------------------------------------------------------------------------
[316]
    “As soon as singing thus those burning Suns
      Had round about us whirled themselves three times,
      Like unto stars neighbouring the steadfast poles.”
                         _Par._ x. 76-78.  (_Longfellow_).
------------------------------------------------------------------------

Remembering this significance of circular motion we shall feel a little
less strange the similes of a mill and a top applied to the spirits of
Paradise.[317]

A third way in which the spirits express their joy is by the sweetness
of their song,[318] and here also they resemble the heavenly bodies,
which make sweet music as they circle. This doctrine of Pythagoras was
very popular throughout the Middle Ages.

------------------------------------------------------------------------
[317] _Par._ xxi. 80, 81; xii. 3; xviii. 41, 42.

[318] _Par._ xxiv. 22-24, x. 73, and many others.
------------------------------------------------------------------------


4. THE GALAXY.

The Galaxy or Milky Way is twice referred to in the _Divine Comedy_. In
_Inf._ xvii. 106-108, it is in connection with the myth of Phaeton, who
being allowed by his father Jove to drive the chariot of the sun for
one day, lost control of his chargers, and going all astray, burned the
sky in a part which still shows signs of this catastrophe, _i.e._ the
Milky Way.

    “Quando Fetòn abbandonò li freni,
     Per che il ciel, come pare ancor, si cosse.”[319]

------------------------------------------------------------------------
[319]
    “What time abandoned Phaëton the reins,
     Whereby the heavens, as still appears, were scorched.”
                      _Inf._ xvii. 107-108.  (_Longfellow_).
------------------------------------------------------------------------

This of course is only a poetical myth. But in the _Paradiso_, in three
lines the appearance, colour, and approximate position of the Galaxy
are described, and allusion is made to the difference of opinions
between learned men with regard to the puzzling question of its
nature. Dante is in the heaven of Mars. He sees the soldier saints,
star-like and fiery red, some larger and some less, thronging thick
in two great bands, which, crossing one another in the depths of the
planet, form a marvellous Crucifix. The crowded lights make him think
of the Galaxy, with its multitudinous points of light, differing in
brightness, although that is white, and lies in a great circle between
the celestial poles.

    “Come, distinta da minori e maggi
       Lumi, biancheggia tra i poli del mondo
       Galassia sì che fa dubbiar ben saggi,
     Sì costellati facean nel profondo
       Marte quei rai il venerabil segno
       Che fan giunture di quadranti in tondo.”[320]

------------------------------------------------------------------------
[320]
    “Even as, distinct with less and greater lights,
       Glimmers between the two poles of the world
       The Galaxy that maketh wise men doubt,
     Thus constellated in the depths of Mars
       Those rays described the venerable sign
       That quadrants joining in a circle make.”
                     _Par._ xiv. 97-102.  (_Longfellow_).
------------------------------------------------------------------------

If we now turn to the fifteenth chapter of Treatise II. of the
_Convivio_, we shall find the Phaeton myth and the various theories
about the Milky Way set forth in due order, and shall learn which of
these Dante considered to be true.

He is comparing the two sciences of Metaphysics and Physics with the
Heaven of the Fixed Stars, and takes the opportunity to tell us some
of the most important facts known about it. Here he calls the Galaxy
a circle:—“La Galassia, cioè quello bianco cerchio che il vulgo
chiama la Via de Santo Jacopo.”[321] This popular name perhaps arose
through a confusion of Galaxy and Galicia, where was a famous shrine
of St. James, and hence came the belief in Italy that the _Galassia_
was a sign by night to guide pilgrims on their way to this shrine at
Compostella in _Galizia_.

------------------------------------------------------------------------
[321] “The Galaxy, that is, the white circle commonly called St.
James’s Way.”
------------------------------------------------------------------------

Dante proceeds as follows with his comparison:—

    “E per la Galassia, ha questo cielo grande
    similitudine colla Metafisica. Perchè è da sapere
    che di quella Galassia li filosofi hanno avuto
    diverse opinioni. Chè li Pittagorici dissero che ’l
    sole alcuna fiata errò nella sua via, e, passando
    per altre parti non convenienti al suo fervore,
    arse il luogo, per lo quale passò; e rimasevi
    quell’ apparenza dell’ arsura. E credo che
    si mossero dalla favola di Fetonte, la quale
    narra Ovidio nel principio del secondo di
    _Metamorfoseos_. Altri dissero (siccome fu
    Anassagora e Democrito) che ciò era lume del sole
    ripercosso in quella parte. E queste opinioni
    con ragioni dimostrative riprovarono. Quello che
    Aristotile si dicesse di ciò, non si può bene
    sapere, perchè la sua sentenza non si trova cotale
    nell’ una traslazione come nell’ altra. E credo
    che fosse l’errore de’ traslatori; che nella
    Nuova par dicere che ciò sia uno raunamento di
    vapori sotto le stelle di quelle parte, che sempre
    traggono quelli; e questa non pare avere ragione
    vera. Nella Vecchia dice, che la Galassia non è
    altro che multitudine di stelle fisse in quella
    parte, tanto picciole che distinguere di quaggiù
    non le potemo, ma di loro apparisce quello albore
    il quale noi chiamiamo Galassia. [E puote essere
    che il cielo in quella parte è più spesso, e
    però ritiene e ripresenta quello lume] e questa
    opinione pare avere, con Aristotile, Avicenna e
    Tolommeo. Onde conciossiacosachè la Galassia sia
    uno effetto di quelle stelle le quali non potemo
    vedere, se non per lo effetto loro intendiamo
    quelle cose, e la Metafisica tratta delle prime
    sustanze, le quali noi non potemo simigliantemente
    intendere se non per li loro effetti; manifesto è
    che ’l cielo stellato ha grande similitudine colla
    Metafisica.”[322]

------------------------------------------------------------------------
[322]
    “And in the Galaxy this heaven has a close
    resemblance to Metaphysics. Wherefore it must be
    known that the Philosophers have had different
    opinions about this Galaxy. For the Pythagoreans
    affirmed that the sun at one time wandered in its
    course, and in passing through other regions not
    suited to sustain its heat, set on fire the place
    through which it passed; and so these traces of the
    conflagration remain there. And I believe that they
    were influenced by the fable of Phaëton, which Ovid
    tells at the beginning of the second book of the
    _Metamorphoses_. Others (as for instance Anaxagoras
    and Democritus) said that the Galaxy was the light
    of the sun reflected in that region. And these
    opinions they confirmed by demonstrative reasons.
    What Aristotle may have said about it cannot be
    accurately known, because the two translations give
    different accounts of his opinion. And I think that
    any mistake may have been due to the translators,
    for in the _New Translation_ he is made to say
    that the Galaxy is a congregation, under the stars
    of this part of the heaven, of the vapours which
    are always being attracted by them; and this
    opinion does not appear to be right. In the _Old
    Translation_ he says that the Galaxy is nothing but
    a multitude of fixed stars in that region, stars
    so small that they are not separately visible from
    our earth, but the appearance of whiteness which
    we call the Galaxy is due to them. [And it may be
    that the heaven in that part is more dense, and
    therefore retains and reproduces that light] and
    this opinion Avicenna and Ptolemy appear to share
    with Aristotle. Therefore, since the Galaxy is an
    effect of those stars which cannot be perceived
    except so far as we apprehend these things by
    their effect, and since Metaphysics treats of
    primal substances which in the same way we cannot
    apprehend except by their effects, it is plain that
    there is a close resemblance between the starry
    heaven and Metaphysics.”
                    _Conv._ II. xv. 44-86.  (_Jackson_).
------------------------------------------------------------------------

This characteristic passage is interesting for several reasons. It
illustrates the mediæval fondness for allegory, the reluctance to
believe that Aristotle could ever be wrong, and the interest in ancient
Greek speculations, in all of which Dante expresses the feelings of his
age: and it brings vividly before us the methods and the difficulties
of mediæval authors. For Dante is repeating from Albertus Magnus
all these ancient speculations: the officious copyist who altered
Aristotle’s words, the fact that Aristotle could only be read in
Latin, and the variety of translations, were all everyday obstacles
to study; and Dante’s own book has suffered from one of them in this
very passage. The words placed between brackets are evidently an
interpolation (as Mr. Wicksteed observes in the “Temple” _Convivio_):
without them the passage goes on smoothly and logically to its end.
On the assumption that the Galaxy is composed of a multitude of small
stars, but not that the sky is denser in that part, the parallel with
Metaphysics holds good.

Dante therefore held the true opinion about the Milky Way, but he was
mistaken in thinking that he had the support of Aristotle. It was the
“New Translation” (made by Aquinas from the Greek) which gave his
opinion correctly; in the “Old” (made by Michael Scot from the Arabic)
his statement had been apparently changed without comment into one
which seems to Dante—and also to us—to represent the truth about the
Galaxy.


5. THE PLANETS.

All the planets which were known before the days of the telescope are
mentioned by Dante several times. Each has its peculiar beauty, but “la
lucentissima stella di Venere”[323] is brighter and more beautiful than
any other. He speaks of “la chiarezza del suo aspetto, ch ’è soavissima
a vedere più che altra stella.”[324]

------------------------------------------------------------------------
[323] “That most brilliant star, Venus.” _Conv._ II. iv. 88.

[324] “The brightness of her appearance, which is more lovely to behold
than that of any other star.” _Conv._ II. xiv. 112, 113.
------------------------------------------------------------------------

No reader of the _Purgatorio_ can ever forget that matchless morning on
which Dante, escaping at last from the murky gloom of the _Inferno_,
sees the sky once more, pure blue even to its furthest limits, and the
planet of love shining in the east.

    “Dolce color d’oriental zaffiro,
       Che s’accoglieva nel sereno aspetto
       Dell’ aer, puro infino al primo giro,
     Agli occhi miei ricominciò diletto,
       Tosto ch’ i’ uscii fuor dell’ aura morta,
       Che m’avea contristati gli occhi e il petto,
     Lo bel pianeta che ad amar conforta
       Faceva rider tutto l’oriente,
       Velando i Pesci ch’erano in sua scorta.”[325]


------------------------------------------------------------------------
[325]
    “Sweet colour of oriental sapphire,
      Which was gathering in the serene aspect
      Of the sky, pure even to the first circle,
    To my eyes restored delight,
      So soon as I had come forth from that dead air,
      Which had troubled eyes and breast.
    The fair planet that inspires love
      Was making all the orient smile,
      Veiling the Fishes which were in her train.”

Alternative rendering of the first three lines:—

    “Sweet colour of oriental sapphire,
      Which was diffused over the tranquil scene,
      From mid-heaven even to the first circle.”
                               _Purg._ i. 13-21.
------------------------------------------------------------------------

Strange to say, the beginning of the above beautiful passage which
conveys so direct and vivid an impression of blue sky and pure air,
presents some difficulties when one comes to translate it word by
word, especially as the texts offer more than one reading. By some
commentators the “primo giro”[326] has been understood to mean the
sphere of the moon,[327] or even the highest sphere (the Primum
Mobile); but this is certainly inadmissible, as Dante supposed the
atmosphere to reach only as far as the sphere of Fire, which came
between it and the moon. The prime circle is here evidently the
horizon, the fundamental circle of observers, the First Circle of the
astrologers, from which they reckoned all the rest. It is here that the
sky usually becomes pale and misty, however blue and clear it may be
above. The colour was gathering and deepening,[328] especially in the
east, where Dante was looking, as dawn began to appear in a perfectly
cloudless sky; for during the darkness of the night it would have
appeared almost black.

------------------------------------------------------------------------
[326] First, or prime, circle.

[327] _Conv._, II. iv. 1-3.

[328] Literally, “was assembling,” or “was being collected.”
------------------------------------------------------------------------

Dr. Moore thinks the authority better for a different reading, viz.
“Dal mezzo”[329] instead of “Dell’ aer.”[330] In this case, we must
take “mezzo puro” to mean mid-heaven, that is the zenith, “puro” being
used as a noun, and meaning a cloudless sky (like “sereno” in _Purg._
v. 38); and “il sereno aspetto” must mean “the quiet scene.”

------------------------------------------------------------------------
[329] “From the middle.”

[330] “Of the air.”
------------------------------------------------------------------------

Venus appears again in the _Purgatorio_, shining upon the Mountain from
the east before sunrise; and this time she is called Cytherea, after
the island near which she was fabled to have risen from the sea, and in
which she received a special worship.

        “Dell’ oriente ... raggiò nel monte Citerea,
    Che di foco d’amor par sempre ardente.”[331]

------------------------------------------------------------------------
[331] “From the east there shone upon the Mountain Cytherea, who in the
flame of love seems to be always burning.” _Purg._ xxvii. 94-96.
------------------------------------------------------------------------

The position of Venus in her course through the zodiac is indicated
in the previous passage by the expression “velando i Pesci.”[332] The
oscillating motion, by which she appears first on the morning and then
on the evening side of the sun is referred to several times. In prose
Dante speaks of her two apparitions, the morning and the evening: “la
sua apparenza, or da mane, or da sera;”[333] in poetry, he describes
her as wooing the sun, first following and then facing him:—

------------------------------------------------------------------------
[332] “Veiling the Fishes” (the zodiacal constellation).

[333] “Her appearance, now in the morning, and now in the evening.”
_Conv._ II. xiv. 114, 115.
------------------------------------------------------------------------

                                        “la stella
    Che il sol vagheggia or da coppa or da ciglio.”[334]

------------------------------------------------------------------------
[334]
                                  “The star
    That woos the sun, now following, now in front.”
                    _Par._ viii. 11-12.  (_Longfellow_).
------------------------------------------------------------------------

Mercury and Venus (called rather oddly after their mothers), are said
both to move closely round the sun:—

               ... “vidi com’ si move
    Circa e vicino a lui Maia e Dione.”[335]

------------------------------------------------------------------------
[335]
        “I saw how move themselves,
    Around and near him, Maia and Dione.”
                             _Par._ xxii. 143-144.
------------------------------------------------------------------------

“Quel bel pianeta di Mercuro”[336] keeps closest, for he is more
hidden than any other in the rays of the sun. Here again the fact is
expressed in simple prose in the _Convivio_:—

------------------------------------------------------------------------
[336]
    “That fair planet, Mercury.”
                             _Son._ xxviii. 9.
------------------------------------------------------------------------

    “Mercurio ... più va velata de’ raggi del sole che
    null’ altra stella.”[337]

------------------------------------------------------------------------
[337] “Mercury ... as it moves is more veiled by the rays of the sun
than any other star.” _Conv._ II. xiv. 99-100.
------------------------------------------------------------------------

which explains (if necessary) the more poetical language of the
_Paradiso_:—

                                “La spera,
    Che si vela ai mortal con altrui raggi.”[338]

------------------------------------------------------------------------
[338]
                         ... “The sphere
    That veils itself from men in alien rays.”
                   _Par._ v. 128, 129.
------------------------------------------------------------------------

In the same way we may compare the descriptions of Mars in the
_Paradiso_ with a statement in the _Convivio_:—

            “Questo fuoco,”[339] and “l’affocato riso della
            stella,”[340] and “Marte rosseggia,”[341] with

------------------------------------------------------------------------
[339] “This Fire.” _Par._ xvi. 38.

[340] “The burning smile of the star.” _Par._ xiv. 86.

[341] “Mars shows red.” _Purg._ ii. 14.
------------------------------------------------------------------------

        “Esso Marte ... il suo calore è simile a quello del
        fuoco; ... esso appare affocato di colore.”[342]

------------------------------------------------------------------------
[342]
    “This Mars ... his heat is like the heat of a fire ...
     his colour is as if he were on fire.”
                               _Conv._ II. xiv. 162-165.
------------------------------------------------------------------------

The famous occultation of Mars by the moon, seen by Aristotle, is
quoted by Dante in _Conv._ II. iii. 59-65.

Jupiter is the “dolce stella”[343] and the “giovial facella.”[344] He
is silvery white, the whitest of all the stars:—“Intra tutte le stelle
bianca si mostra, quasi argentata.”[345]

------------------------------------------------------------------------
[343] “Sweet star.” _Par._ xviii. 115.

[344] “The torch of Jove.” _Par._ xviii. 70.

[345] “Amongst all the stars it shows white, as if silvered over.”
_Conv._ II. xiv. 202-204.
------------------------------------------------------------------------

Therefore when Dante saw the planet filled with brilliant spirits,
he says: “Giove pareva argento lì d’ oro distinto.”[346] Comparisons
between the colours of Jupiter and Mars are made in _Par._ xviii.
64-69, and xxvii. 13-15.

------------------------------------------------------------------------
[346]
                                    “Jupiter
    Seemed to be silver there with gold inlaid.”
                      _Par._ xviii. 95-96. (_Longfellow_).
------------------------------------------------------------------------

Finally Saturn is the slowest and the most distant of all the planets.
These two characteristics are thus described in the _Convivio_:—

    “L’una si è la tardezza del suo movimento per li
    dodici segni; chè ventinove anni e più, secondo le
    scritture degli astrologi, vuole di tempo lo suo
    cerchio: l’altra si è che esso è alto sopra tutti
    gli altri pianeti.”[347]

------------------------------------------------------------------------
[347] “One is the slowness of its movement through the twelve signs;
for twenty-nine years and more, according to the writings of the
astrologers, are required for its revolution: the other is that it is
high above all other planets.” _Conv._ II. xiv. 226-231.
------------------------------------------------------------------------

In the _Paradiso_ Saturn is called a Mirror,[348] a Crystal,[349] a
splendour;[350] his circling motion is alluded to, and his position at
the time in the zodiac:—

------------------------------------------------------------------------
[348] _Par._ xxi. 18.

[349] _Par._ xxi. 25.

[350] _Par._ xxi. 13.
------------------------------------------------------------------------

      “Cerchiando il mondo.”[351]
      “Sotto il petto del Leone ardente.”[352]

------------------------------------------------------------------------
[351] “Circling the world.” _Par._ xxi. 26.

[352] “Beneath the burning Lion’s breast.” _Par._ xxi. 14.
------------------------------------------------------------------------

Some of the most beautiful similes in the _Divine Comedy_ are drawn
from the planets. The angel-pilot of Purgatory, when first seen far
off over the sea, is likened to the planet Mars, glowing red through
morning mists, low in the west above the ocean floor;[353] and the
angel that welcomes the poet to the second circle on the Mountain is
beautiful as the Morning Star.

------------------------------------------------------------------------
[353] _Purg._ ii. 13-15.
    “A noi venia la creatura bella,
     Bianco vestita, e nella faccia quale
     Par tremolando mattutina stella.”[354]

[354]
    “Towards us came the being beautiful,
     Vested in white, and in his countenance
     Such as appears the tremulous morning star.”
                           _Purg._ xii. 88-90. (_Longfellow_).
------------------------------------------------------------------------

Although any of the planets when rising just before the sun may be
called a morning star, Venus is probably intended here, as also where
St. Bernard, in his devotion to the Virgin, is compared with the
Morning Star which takes its beauty from the sun:—

    “Colui ch’abbelliva di Maria,
     Come del sole stella mattutina.”[355]

------------------------------------------------------------------------
[355] “He who drew beauty from Mary, as the Morning Star does from the
Sun.” _Par._ xxxii. 107, 108.
------------------------------------------------------------------------

All the seven planets (that is, including sun and moon), are
occasionally mentioned together, “tutti e sette,”[356] and their
movement in the ecliptic is referred to in _Par._ x, 14: “L’obbliquo
cerchio che i pianeti porta.”[357] In the 14th and 15th chapters of
the second treatise of the _Convivio_, already so often quoted, Dante
draws an elaborate comparison between the seven planets and the seven
sciences of the Trivium and Quadrivium. The moon is Grammar, Mercury
Dialectic, Venus Rhetoric, the Sun Arithmetic, Mars Music, Jupiter
Geometry, and Saturn Astrology. The reasons given for the latter are
the slow movement and the height (_i.e._ distance from Earth) of
Saturn, which Dante compares with the length of the time taken in
learning astronomy, and the loftiness of its subject.

------------------------------------------------------------------------
[356] “All the seven.” _Son._ xxviii. 14, and _Par._ xxii. 148.

[357] “The oblique circle which carries the planets.”
------------------------------------------------------------------------

In the same way the star sphere is said to resemble Physics and
Metaphysics, the Primum Mobile Ethics, and the Empyrean Theology. The
argument is very fanciful, but just what would appeal to readers of
Dante’s day, who loved to find allegories everywhere; and it gives him
an opportunity of instructing them very simply in his beloved science.

He sometimes uses the planetary periods as divisions of time (as Plato
said they should be used), for computing earthly events, and in him
this does not seem affectation, as it would with almost anyone else. It
seems quite natural that Cacciaguida, when speaking in the heaven of
Mars, and answering a question regarding the date of his birth, should
count the time not by solar but by Martian years, saying that from
the beginning of the Christian Era to the day of his birth, Mars had
returned to his Lion (the constellation of Leo) five hundred and eighty
times.[358] The length of the Martian year according to Alfraganus is
1 Persian year, 10 months, and 22 days nearly. The Persian year (as
he tells us in the first chapter of the _Elementa_) consists of 12
months of 30 days each plus 5 extra days, making 365 days exactly (not
365¼ days like the Roman), so the Martian year is 687 days (the modern
estimate is 686·9). 687 days × 580 gives us 1091 a.d. as the date of
Cacciaguida’s birth. This is consistent with the date of his death, for
he had just told Dante that he fell in the Crusade to which he followed
the Emperor Conrad, and we know that this was fought in the year 1147.

Some commentators think that Dante did not intend the Martian year
to be taken so precisely, but only as approximately two solar years,
since he gave it thus in _Conv._ II. xv. 145. But there he specially
states that he is quoting an approximate figure only (“uno anno
quasi”[359] is half the period of Mars) whereas in the _Paradiso_ it
is used to fix a date. Since by taking 580 × 2 years we get 1160, an
impossible date of birth for a man who died in 1147, the only way to
support this theory that Dante was speaking loosely here is to adopt
another reading of the passage, and substitute “tre” for “trenta.”[360]
Then 553 (instead of 580) × 2 years would give the date 1106; but the
reading is not supported by good authority.

------------------------------------------------------------------------
[358] _Par._ xvi. 34-39.

[359] “About a year.”

[360] “Three,” for “thirty.”
------------------------------------------------------------------------

The period of Venus is used with equal appropriateness when Dante is
relating how love for the Gentil Donna found a way to his heart, coming
on the rays of Venus,[361] the star of love.

    “La stella di Venere due fiate ere rivolta in
    quello suo cerchio che la fa parere serotina e
    mattutina, secondo i due diversi tempi, appresso
    lo transpassamento di quella Beatrice beata, che
    vive in cielo con gli angioli e in terra colla mia
    anima, quando quella Gentil Donna, di cui feci
    menzione nella fine della _Vita Nuova_, apparve
    primamente accompagnata d’Amore agli occhi miei, e
    prese alcuno luogo nella mia mente.”[362]

------------------------------------------------------------------------
[361] _Conv._ II. vii. 88, 89.

[362] “The star of Venus had twice revolved in that circle of hers
which makes her appear as evening and morning star, according to her
two seasons, since the translation of that holy Beatrice who lives in
heaven with the angels and on earth in my soul, when that Gentle Lady,
of whom I made mention at the end of the ‘New Life,’ appeared first
before my eyes, escorted by Love, and took some place in my mind.”
_Conv._ II. ii. 1-12.
------------------------------------------------------------------------

Venus runs through her changes, appearing first as Evening and then
as Morning star, in 584 days; and, as the reader will remember,
this movement was ascribed by Ptolemy to her epicycle (“quello suo
cerchio,” “that circle of hers”). Dante would find 584 days given for
it in his Alfraganus.[363] Twice 584 is 1168 days, or three years and a
little more than 2 months. Therefore, since we know from _V. N._ xxx.
that Beatrice died in June 1290, Dante wishes to say that he first saw
the Lady of Pity in August 1293.

------------------------------------------------------------------------
[363] “Venus [ambitum epicycli peragit] anno Persico 1, mensibus 7,
et diebus prope 9,” that is, the period of Venus on her epicycle is
365 + 210 + 9 = 584 days nearly, according to Alfraganus. The modern
mean value is also 584 days.
------------------------------------------------------------------------

The period has been taken by some modern commentators to refer to the
225 days in which Venus revolves round the sun, but this period has no
place in the Ptolemaic system. We cannot here discuss Dante’s allegory
of the Gentle Lady and Philosophy, but in this passage he has stated
without ambiguity or uncertainty the date of her first appearance.[364]

------------------------------------------------------------------------
[364] See Lubin’s _Dante e gli Astronomi Italiani_. The period of 225
days may be easily deduced from Ptolemy’s system, for it is the time in
which the epicycle of Venus would make an absolute revolution round its
centre, the diameter becoming parallel to its former position. But the
Greeks invariably reckoned the period as the time in which it revolved
relatively to Earth, that is 584 days.
------------------------------------------------------------------------


6. ECLIPSES.

We find solar eclipses mentioned six times in Dante’s works. As in all
old records, there is no allusion to the features which chiefly strike
modern astronomers—the pearly corona, and the blood-red prominences
standing out like flames round the black disc. The terror of the sudden
darkness, even when foreseen, seems to have absorbed all attention,
and only the appearance of stars in the daytime and the frightened
behaviour of animals was noted by Ristoro, and by others until quite
modern times.

In his letter to the Cardinals of Italy, Dante speaks of the shameful
and grievous removal of the Papacy from Rome to Avignon as an eclipse
of the sun.[365] In his dream of the death of Beatrice, he sees the sun
so darkened that the stars appear, to his great terror:—

------------------------------------------------------------------------
[365] _Ep._ viii. 158, 159.

    “Poi mi parve vedere appoco appoco
    Turbar lo Sole ed apparir la stella.”[366]

[366]
    “The while, little by little, as I thought,
     The sun ceased, and the stars began to gather.”
                      _V. N._ xxiii. 176, 177. (_Rossetti_).

See also the prose description just before, lines 35-37.
------------------------------------------------------------------------

He also refers to the disputed idea that the darkness at the time of
the Crucifixion was caused by an eclipse of the sun,[367] and to the
figurative eclipse which then took place in heaven.[368]

------------------------------------------------------------------------
[367] _Par._ xxix. 97-102.

[368] _Par._ xxvii. 35, 36.
------------------------------------------------------------------------

If he had ever seen one in reality, it would have made more impression
upon him, and we should surely have found it referred to several times
and vividly described. The only suggestion of a personal experience is
where he temporarily loses the power of sight by gazing too fixedly
upon the spirit of St. John; and he compares this to a man who looks so
intently at the sun, just before an eclipse, that he becomes incapable
of seeing it at the critical moment.[369] This incident may have been
told him by an observer of the total eclipse of June 1239, which was
visible in Italy, and seems to be the one described by Ristoro.

Lastly, he mentions the discovery that the moon comes between us and
the sun, which we have learned from eclipses, as an example of the
proper method of reasoning: for we must first ask whether a thing is,
and afterwards why it is. Thus man’s wonder leads him to knowledge.[370]

------------------------------------------------------------------------
[369] _Par._ xxv. 118-121.

[370] _Qu._ xx. 3-5, 26-29.
------------------------------------------------------------------------

The eclipsed moon is only once mentioned, viz. in _De Mon._ III. iv.
140-142, where she is described as not wholly dark. With his usual
indifference to her Dante fails to note the often extraordinary beauty
of her colouring when the eclipse is total.


7. COMETS AND METEORS.

The connection between these two classes of heavenly bodies seems to be
real, though its exact nature is still a mystery. In old days little
or no distinction was drawn between them, so that it is sometimes
difficult to know whether a writer is describing a large meteor, or a
comet, or a shower of falling stars.

Dante only mentions comets once, very briefly, when he describes
spirits in Paradise as “fiammando forte a guisa di comete.”[371] He
says nothing of the magnificent comet described by Ristoro, which
rose at three o’clock in the morning, huge as a mountain, and with
great rays like a mane; but travelling always towards the south grew
gradually fainter, and disappeared after 60 days. Yet it was seen in
Tuscany shortly before Dante’s birth, and it was thought to herald the
death of the Pope (Urban IV. in 1264) and the terrible war in which
first Manfred and afterwards Conradin were slain. These events are
familiar to every reader of the _Divine Comedy_,[372] but there is
never any mention of the comet.

------------------------------------------------------------------------
[371] “Blazing brilliantly like comets.” _Par._ xxiv. 12.

[372] _Inf._ xxviii. 16-17; _Purg._ iii. 112-132.
------------------------------------------------------------------------

Nor does he describe in any detail the fiery cross which was seen in
the sky above Florence “in the beginning of her destruction,” which
does not mean, as one might think, the legendary sack of the city
by Totila, but the treacherous entry of Charles of Valois, “Totila
secundus,”[373] in November 1301. This portent was of course considered
as of ill omen for the Republic, and although Dante was still absent
on his embassy to Rome, and cannot have seen it himself, it is rather
remarkable that he says so little about it. It is described by an
eye-witness, “Io, che chiaramente la viddi”[374] as a red cross which
appeared in the evening over the Priors’ Palace; the vertical arm
seemed to be 20 ells long, the transverse one a little shorter, and
it remained visible for as long as it would take a horse to gallop
two furlongs. Villani the historian describes it as like a comet with
an immense trail, as of smoke, behind it. Dante merely mentions it,
together with the ball of fire seen by Seneca at the death of Augustus,
which, judging by Seneca’s own words, was also a large meteor, for
he describes it as flashing into sight and moving very rapidly,
disappearing as it moved.[375]

------------------------------------------------------------------------
[373] _V. E._ II. vi. 48.

[374] “I, who saw it clearly.”

[375] _Naturales Quæstiones_, Bk. I.
------------------------------------------------------------------------

Dante calls meteors “kindled vapours,”[376] in accordance with the
doctrines of Aristotle, but the popular idea of them is shown by his
observation that they might be taken for stars in motion, only that
no star vanishes from its place, and they are only seen for a short
time.[377] Ristoro d’Arezzo had already alluded to this fallacy:—

------------------------------------------------------------------------
[376] _Conv._ II. xiv. 168-171, and _Purg._ v. 37.

[377] _Par._ xv. 16-18.
    “Alquanti non savi credono ch’elle sieno stelle,
     che caggino del cielo e vengano meno.”[378]

[378] “Some ignorant people think that they are stars which fall from
heaven and vanish.” _Comp. del Mondo_, VII. v.
------------------------------------------------------------------------

He gives the same reason as Dante for disbelieving this, and Seneca had
expressed it more forcibly, saying that if true there would be no more
stars in the sky, for some meteors are seen every night.

Albertus Magnus, who seems to have had a genius for mistaking his
authorities, quotes Alfraganus as stating that shooting stars are most
frequent in evening twilight, though nothing of the kind is said in the
_Elementa._ Dante perhaps accepted the statement, though it is by no
means necessarily implied in his “di prima notte:”[379] moreover there
is some authority for the alternative reading of “mezza notte.”[380]
Wherever the idea originated, its sole foundation must have been the
circumstance that more persons are awake in the early than in the late
hours of the night: the fact is that more meteorites are captured by
the morning side of the earth, which is turned in the direction towards
which she is moving in her orbit.

------------------------------------------------------------------------
[379] “Early in the night.”

[380] “Midnight.” _Purg._ v. 38.
------------------------------------------------------------------------

Shooting stars were necessarily familiar to a lover of starry skies,
and Dante has given us an exquisite description of the suddenness with
which they startle quiet eyes, while their brilliancy and swiftness of
flight provides him with two beautiful similes.

In the first he compares them, and also flashes of summer lightning,
with messenger spirits in Purgatory hastening to bring their friends to
him:—

    “Vapori accesi non vid’ io sì tosto
       Di prima notte mai fender sereno,
       Nè, sol calando, nuvole d’agosto,
     Che color non tornasser suso in meno,
       E giunti là, con gli altri a noi dier volta.”[381]

------------------------------------------------------------------------
[381]
    “Vapours enkindled saw I ne’er so swiftly
       At early nightfall cleave the air serene,
       Nor, at the set of sun, the clouds of August,
     But upward they returned in briefer time,
       And on arriving with the others, wheeled
       Towards us.”
                        _Purg._ v. 37-41. (_Longfellow_).

(By “vapours that cleave the clouds of August,” flashes of lightning
without thunder are meant. Aristotle believed both these and meteorites
to be ignited vapours).
------------------------------------------------------------------------

The second illustrates the brightness and beauty, as well as the
movement, of the star-like spirits in Mars:—

    “Quale per li seren tranquilli e puri
       Discorre ad ora ad or subito foco,
       Movendo gli occhi che stavan sicuri,
     E pare stella che tramuti loco,
       Se non che dalla parte ond’ ei s’ accende
       Nulla sen perde, ed esso dura poco ...”[382]

------------------------------------------------------------------------
[382]
    “As through the pure and tranquil evening air
       There shoots from time to time a sudden fire,
       Moving the eyes that steadfast were before,
     And seems to be a star that changeth place,
       Except that in the place where it is kindled
       Nothing is missed, and this endureth little.”
                         _Par._ xv. 13-18. (_Longfellow_).
------------------------------------------------------------------------


8. THE SUN’S PATH IN THE SKY SEEN FROM DIFFERENT PARTS OF THE EARTH.

We have now seen how familiar Dante was with the aspects of the skies
above his head. His writings show also that he had pictured clearly
to himself what they must be in other parts of the world—in regions
far east or west, in the southern hemisphere, at the equator, and at
either pole. Science could not tell him all that he would have liked to
know about the stars, so that although he can speak of regions where
Ursa Major passes overhead, and where it sinks out of sight below
the horizon, he has to fall back upon his imagination and invent new
constellations for the southern hemisphere.

But astronomy could tell him, and his habit of accurate thought,
as well as his imagination, helped him to grasp how the sun would
appear at any latitude on the earth, and what would be the results on
the length of day and night, and on the seasons. A very interesting
little disquisition on this subject is found in the _Convivio_, in
illustration of some lines in one of his Odes, which speak of the sun
circling the whole world. In order to understand this completely, Dante
says, we must know exactly in what way the sun circles the world. The
chief point to bear in mind while reading his description is that the
sun, besides the simple daily motion in a circle, has a constant slow
motion north or south, and therefore his path in the sky, as we see it
day after day, is really spiral.

The passage is much too long to quote in full, but if the reader will
follow me, taking his _Convivio_ and opening it at chapter v. of
Treatise III. and beginning at line 66, I will give a résumé which will
form a running commentary on the text, and an explanation of any points
which may not at once be clear.

We see the sky, says Dante, continually revolving round Earth as
centre; and it has two fixed poles of revolution—the northern, which is
visible to nearly all the land not covered by sea, and the southern,
which is hidden from nearly all of it. And the circle which is
equi-distant from these two poles [the celestial equator] is that part
of the sky in which we see the sun when he is in Aries and in Libra.

Now if a stone could be dropped from this pole of ours [the northern],
it would fall far away yonder in the ocean just where, if a man were
standing, he would always have the Pole Star exactly overhead. [“La
stella”[383] is the Pole Star, see p. 291]. And I believe (Dante says)
that from Rome to the north pole, in a direct line, is a distance
of about 2,700 miles. To fix our ideas, let us imagine that at this
spot there is a city called _Maria_, and let us imagine another city,
called _Lucia_, at the spot exactly opposite, where a stone would
fall if dropped from the other pole. And I believe that from Rome
southwards to this second place would be a distance of about 7500
miles. Thus the distance between the two cities, in whatever direction
the measuring cord be stretched, would be 10,200 miles, that is, half
the circumference of the globe,[384] and the inhabitants of _Maria_
would have their feet opposite the feet of those of _Lucia_. [If any
two spots on a sphere are exactly antipodal, but in no other case, the
distance may be measured in an infinity of directions, and always come
out the same.]

------------------------------------------------------------------------
[383] “The star.”

[384] As this is the value given by Alfraganus, we must here understand
Arabian miles. The distances from Rome to the north and south pole are
therefore probably equal to 3500 to 9750 English miles, and both are a
little too large, because the half circumference of Earth is too large.
The proportion is about right, however, for Rome is nearly three times
as far from the south pole as the north, her latitude being 42° N.
Alfraganus placed her in the fifth climate, at the northern boundary of
which he said the pole was elevated 43½°.
------------------------------------------------------------------------

Lastly, let us imagine a circle on the globe, which will be at equal
distances everywhere from _Maria_ and _Lucia_ [the equator]. According
to the opinions of the astrologers, if I understand them aright,
and according to what is said by Albertus Magnus and by Lucan, this
circle would divide the dry land from the ocean there in the south,
approximately along the extremity of the First Climate, where amongst
others live the Garamantes, who go almost always naked, to whom Cato
went when fleeing from Cæsar.

“Approximately,” because the southern extremity of the First Climate,
according to Alfraganus, lay a little north of the equator, although
land extended, and was sparsely inhabited, as far the equator (see p.
186).

Dante speaks again of these extra-climatal races in _De Mon._ I. xiv.
43-51, where he contrasts the Scythians who live beyond the seventh
climate, and therefore endure extreme inequality of days and nights,
and suffer almost intolerable cold, with the Garamantes who live under
the equator, where days and nights are always equal, and the heat
is so intense that they can scarcely bear any clothing. Since “the
astrologers who determine the climates”[385] had fixed their northern
limit at 50½°, nearly the whole of Britain also lay, like barbarous
Scythia, in this scarcely habitable region of long nights and bitter
cold!

------------------------------------------------------------------------
[385] _Qu._ xix. 36.
------------------------------------------------------------------------

When we have marked these three places on the globe, _i.e._ the two
poles and the equator, it is easy (Dante goes on) to see how the sun
circles. I say then, that the heaven of the sun turns from west to
east, not directly against the diurnal movement—that is, the movement
which produces day and night—but obliquely against it, and so that its
middle circle, which is similarly between its two poles, and on which
is the body of the sun [_i.e._ the ecliptic], cuts in two opposite
points the circle of the two first poles [the equator], that is, at the
beginning of Aries and the beginning of Libra; it diverges from that
circle in two arcs, one north and the other south. The highest points
of these arcs are equally distant from the first circle in either
direction, being 23 degrees and a little more; and the one summit is at
the beginning of Cancer, and the other at the beginning of Capricorn.

Therefore, when the sun is in the beginning of Aries, travelling in
the mid-circle of the first poles [the equator], _Maria_ will see this
sun circling the world, low down on the ground, or on the sea, like
a mill-stone only half of which is seen, and day after day he will
be seen to rise, like the screw of a press, until he has performed
about ninety revolutions, or a little more. When these revolutions are
accomplished, he will be as high in the sky above _Maria_ as he stands
in the sky of the Garamantes at middle-tierce at the time of equal days
and nights.[386]

------------------------------------------------------------------------
[386] Adopting the reading of Dr. Moore: “nella mezza terra, alla mezza
terza,” that is, “at the equator at middle-tierce.” See _Studies in
Dante_ III. 107, 108.
------------------------------------------------------------------------

[From _Conv._ IV. xxiii. and III. vi., where Dante explains the use
of temporal hours, we learn that mid-tierce on the day of the equinox
is an hour and a half after sunrise, or 7.30 A.M. Since the sun moves
through 360 degrees divided by 24, that is 15 degrees, in an hour,
and his motion is vertical in equatorial countries at the equinox,
it would bring him in 1½ hours to 22½ degrees above the horizon. His
greatest height above the horizon at the pole is only one degree more
than this, for it is obviously equal to the greatest distance between
the equator and the ecliptic, _i.e._ 23½ degrees, since at the pole the
equator coincides with the horizon. This gives a good idea, therefore,
of the appearance of the sun in the sky to the people at _Maria_, and
is a striking illustration of the difference between the polar sun and
the equatorial. For at the time mentioned, the sun has only a quarter
the height which it will attain at noon, when it will pass through the
zenith of the Garamantes; yet this is the highest position in which the
inhabitants of _Maria_ can ever see it].

If a man stood upright in _Maria_, and kept turning his face to the
sun, he would see it move to his right [as we do].

After reaching his greatest height in the sky, the sun would begin to
descend again, in the same spiral way like a screw turning, for another
ninety revolutions or so, until once more he was circling down on the
horizon, only half his body visible.

Then he would be lost to sight altogether, and would begin to be seen
in _Lucia_, where he would rise and descend in just the same way as in
_Maria_. But if a man faced the sun in _Lucia_, he would see it moving
to his left [as one does in Australia where it goes north at noon].

[Illustration: Fig. 43. The Sun at the Equinox, seen from the poles and
the equator. _Conv._ III. v.

(Maria, Lucia, imaginary cities at the North and South poles).]

We see, then, that these places have one day in the year which is six
months long, and one night of equal length, and when it is day with
one, it is night with the other.

Now on the circle on the globe where the Garamantes live [the equator],
the sun when in Aries goes exactly overhead, not circling horizontally
like a mill-stone, but vertically like a wheel, and exactly half of
this wheel is visible above the horizon.

After this, the sun is seen to depart and go towards _Maria_ for about
91 days; then in about the same time it returns, and enters Libra; then
it goes towards _Lucia_ for about 91 days, and in the same period
returns. And this place, which circles the entire globe, always has
equal day and night, on whichever side of it the sun is; and twice in
the year it has a very hot summer, and twice a mild winter.

The regions which are between the two imaginary cities and the
mid-circle, see the sun in different ways, according to their distance
from these places, but the details, our author says, he will leave to
the ingenious reader,

    “Siccome omai, per quello che detto è, puote vedere
    chi ha nobile ingegno, al quale è bello un poco di
    fatica lasciare.”[387]

------------------------------------------------------------------------
[387] “For now, after what has already been said, the rest may be
understood by whomsoever has a noble mind, to which it is well to leave
a little labour.” (_Cf. Par._ x. 22-25).
------------------------------------------------------------------------

He draws attention to the interesting fact, which follows from the
above, that in the course of a year (when the heaven of the sun has
made a complete revolution and returned to the same place), every
part of this globe on which we live has received an equal amount of
daylight. And the essay ends in an apostrophe which recalls the reproof
of Virgil to those who will not look up to the skies:[388]

    “O ineffabile Sapienza che a così ordinasti, quanto
    è povera la nostra mente a Te comprendere! E voi,
    a cui utilità e diletto io scrivo, in quanta
    cecità vivete, non levando gli occhi suso a queste
    cose, tenendoli fissi nel fango della vostra
    stoltezza.”[389]

------------------------------------------------------------------------
[388] _Purg._ xiv. 148-151.

[389] “O unspeakable Wisdom who hast thus ordained, how poor is our
intellect to understand Thee! And you, for whose benefit and pleasure
I am writing, in what blindness you live, not lifting up your eyes to
these things, but keeping them fixed on the slough of your folly.”
------------------------------------------------------------------------

It is interesting to compare this passage with the parallel passages
in Alfraganus and Ristoro. The astronomer is concise and clear; the
monk is diffuse and apt to repeat himself; the poet is quaintly
picturesque. Both the Italians evidently draw the main facts from
the Arab, and all use the illustration of a mill-stone to explain
the horizontal motion of the heavens at the pole: here are the three
corresponding passages:—

           “Coelumque molæ trusatilis instar gyrum
            vertitur.”[390]

           “Lì si volgera il cielo attorno con tutte le sue
            stelle, in modo di macina.”[391]

           “Conviene che _Maria_ veggia ... esso sole ‘girare
            il mondo’ ... come una mola.”[392]

------------------------------------------------------------------------
[390] “And the sky revolves like a mill-stone.” _El. Ast._ ch. vii.

[391] “There the sky will revolve, with all its stars, mill-stone
        fashion.” _Comp. del Mondo._ I. xxiii.

[392] “It follows that _Maria_ must see this sun ‘circling the world’
like a mill.” _Conv._ III. v. 142-147.
------------------------------------------------------------------------

Dante alone uses the figure of a wheel to illustrate the vertical
motion at the equator; he perhaps takes from Ristoro the idea of
the spiral. For the latter describes the path of the sun as a “via
tortuosa, la quale i savi chiamano spira;”[393] but he explains it as
like a string wound round a stick, Dante like the screw of a press.
Dante is dealing only with the sun, and does not enter into details
about the visibility of the zodiacal signs like the other two authors;
but on the other hand he goes south to the other pole, which apparently
does not interest the others, perhaps because the southern hemisphere
was thought to be uninhabited. But the poet has added life to his
description by supposing both poles inhabited, placing there his
imaginary, mysteriously-named cities of “Maria” and “Lucia.” On the
equator, where Ristoro has the mythical city of Arym, whose wise and
prosperous citizens enjoy a perfect climate, Dante, relying more on the
classics, lets his barbarous Garamantes run about naked most of the
year, under the fierce equatorial sun.

Needless to say, his little homily in conclusion is all his own;
it is more interesting to find that he alone mentions the opposite
movements of the Sun, to right and left respectively in the north and
south hemispheres,[394] and the fact that every part of the earth
receives the same amount of sunlight in a year. This may have been
suggested by someone else, but one would like to think he arrived at it
independently, when thinking over the facts.

------------------------------------------------------------------------
[393] “A winding path, which the learned call a spiral.”

[394] “Lucan, who was well known to Dante, had observed that shadows
cast by the sun in the southern hemisphere travel to the right instead
of to the left, and fall southwards when with us they fall to the
north.” Moore, _Studies in Dante_ i. p. 239.
------------------------------------------------------------------------

In the light of this treatise, which describes so truthfully the path
of the sun, and its effect on the seasons in different latitudes, we
may explain two rather puzzling passages in the _Divine Comedy_.

One is at the beginning of the tenth canto of the _Paradiso_, where
Dante wishes his readers to realize the position of the sun when he
entered it with Beatrice, and the great importance of this position.
“Lift your eyes with me, reader,” he says, “to that place in the lofty
heavens where the one motion meets the other, and see how the oblique
circle which carries the planets branches off from that point.” The
reader is now familiar with the “two chief motions,” and knows that one
is the diurnal, from east to west, the other the planetary periodical
motions in the opposite direction; they meet at the equinoxes, where
the ecliptic cuts the equator. It is the spring equinox which Dante is
speaking of, for a little further on he says that the sun, situated
in the place above-mentioned, was circling in those spirals which
bring him to us earlier every day (lines 31-33). Now if the path
of the planets were not thus oblique, he continues, much virtue in
heaven would be lost, and almost every earthly power dead. Even if the
obliquity were merely less or more, the universal order of both heaven
and earth would suffer greatly. But why this should be so he leaves his
readers to think out for themselves, having a greater matter in hand
which demands all his attention.

It is easy to see that if the sun always moved in the equator, without
departing from it either north or south, he would rise every day to
the same height in the sky, and there would be no change of seasons
anywhere on the earth; he would always be overhead at noon to Dante’s
Garamantes, living on the equator, and always just on the horizon, day
and night, to the people of “Maria” and “Lucia” at the Poles. If the
ecliptic made a greater angle with the equator the seasons would be
more marked, and the sun would rise higher in summer in high latitudes.
If the angle were less, the reverse would be the case. Moreover if sun
and moon and all the planets followed the same track, they would be
constantly eclipsing one another.

But if we would understand the full meaning of—

    “Se la strada lor non fosse torta,
     Mota virtù nel ciel sarebbe in vano,
     E quasi ogni potenza quaggiù morta.”[395]

------------------------------------------------------------------------
[395]
    “If their pathway were not thus inflected,
     Much virtue in the heavens would be in vain,
     And almost every power below here dead.”
                          _Par._ x. 16-18. (_Longfellow_).
------------------------------------------------------------------------

we must turn to thirteenth-century Ristoro of Arezzo, who has set forth
in detail the results which he believed would follow from a change in
the ecliptic. If all the seven planets moved in the same narrow path,
there would be much less variety in their “aspects,” and therefore
in their influences upon the earth; and in the frequent eclipses one
would prevent the other from looking at the earth (“impedimenterebbe
l’uno l’altro a guardare la terra”), and so hinder its action. And
since it is the northward movement of the sun which causes our plants
to blossom, and later to bear fruit, if there were no such motion we
should see no renewal of life. He argues further that if the obliquity
of the ecliptic were greater, countries in high latitudes would have
too severe a winter to be inhabited; while if it were less, the summer
there would not be warm enough for the ripening of harvests; therefore
in whichever way it differed from the actual value, a smaller part of
the earth would be habitable.

    “Or ti riman, lettor, sopra il tuo banco,
    Dietro pensando a ciò!”[396]

------------------------------------------------------------------------
[396]
    “And now remain, reader, on your bench, thinking over this!”
                                           _Par._ x. 22, 23.
------------------------------------------------------------------------

How much of this was in Dante’s mind it is hardly possible to say,
but it is evident that the “via tortuosa” of the seven planets, and
its effects on the earth, was a favourite subject for thought in his
time.[397]

------------------------------------------------------------------------
[397] Thus Petrarch: “Le stelle vaghe e lor viaggio torto.” (“The
wandering stars and their winding way.”) _Sonetto de Morte di Madonna
Laura._
------------------------------------------------------------------------

But the most famous passage relating to the sun’s path and its aspect
in strange latitudes is _Purg._ iv. 52-84.

Here Dante is able at once to understand the startling appearance
of the sun travelling to his left instead of his right, as seen on
the first morning in Purgatory, for he grasps the full meaning of
Virgil’s explanation, and caps it, in a way which seems astonishingly
quick-witted to unastronomical readers!

The two poets had begun to climb the mountain just at sunrise, and sat
down to rest on a ledge at about half-past nine, looking east. Dante
at first looked down at the shore, whence he had so painfully climbed,
then raised his eyes to the sun, and was amazed to find that its rays
struck him on the left shoulder.

Virgil, seeing his astonishment, explains why the sun is going north
instead of south as it climbs the sky. The sun is now in Aries, and
therefore on the equator, as we know from several passages, but Virgil
begins by saying that if it were in Gemini [a more northerly sign] and
kept to its ancient path, Dante would see it travelling still further
northwards in its daily course. “If Castor and Pollux [stars in Gemini]
were in company with that Mirror [the sun] which carries his light up
and down [_i.e._ goes north and south alternately], you would see the
glowing zodiac [that part in which the sun is] revolving still closer
to the Bears.” Gemini is literally nearer to the constellations of the
Bears than Aries, but this is not the sense of Virgil’s statement: he
means merely to indicate the north in general (see Ptolemy, p. 157).
“To understand why the sun goes north,” Virgil says, “you must know
that this mountain and Zion [Jerusalem] are so situated on the earth
that one is precisely antipodal to the other; and so, the sun’s path
being between them, when he is viewed in one direction from Jerusalem,
he is viewed in the opposite direction from Purgatory. If you turn from
the east to your right to see him from Jerusalem, you must turn to your
left in Purgatory.” Virgil speaks of the sun’s path or the ecliptic as
the path which Phaëton was not able to keep, and he describes the two
antipodal places as having one and the same horizon but two entirely
different hemispheres.

“Certainly,” replies Dante, “I have never seen anything so clearly as
I now perceive what at first puzzled me. For the middle circle of the
celestial motion,[398] which is called the equator in a certain art
[astronomy], and which always remains between the sun and winter, [the
sun crosses it departing from us in either hemisphere at the autumnal
equinox], here lies to the north of us, for the reason you have given
[namely, that we are in the southern hemisphere], whilst the Hebrews
[inhabitants of Jerusalem] see it towards the hot region [the south].”

Observe that the expression used of the equator “che sempre riman
tra il sole e il verno,”[399] distinctly suggests the reversed
seasons in the southern and northern hemispheres, so that Dante has
no intention, as Dr. Moore suggests, of assuming by a poetic licence
that it is spring in Purgatory as well as in Italy.[400] It is autumn
in the southern hemisphere, but this need not distress us: the holy
Mountain knows no inclement weather,[401] and in the Garden of Eden
on its summit spring flowers and autumn fruits eternally flourish
together.[402]

An allusion is made to a tropical summer in “la terra che perde
ombra.”[403] Tropical Africa is intended, where the sun at certain
times passes directly overhead, and therefore casts no shadows, as the
Alexandrian astronomers had observed (see p. 117).

------------------------------------------------------------------------
[398] _Cf. Conv._ III. v. 76, 191.

[399]
    “Which always remains between the sun and the winter.”
                                        _Purg._ iv. 81.

[400] _Studies in Dante_ iii. p. 166.

[401] _Purg._ xxi. 46-48; _Purg._ xix. 38.

[402] _Purg._ xxviii. 143.

[403] “The land where shadows are lost.” _Purg._ xxx. 89.
------------------------------------------------------------------------

Did Dante believe that no land exists anywhere in the southern
hemisphere? There are some indications that he thought it possible to
push the limits of the habitable earth a little beyond the equatorial
boundary of Alfraganus. There would be no heresy in lengthening the
southward extremities of Africa or Asia, because all that the Church
forbade was to plant another land in the south, separated from us
by a vast ocean or impassable torrid zone, and to people it with
inhabitants, who could not therefore be descendants of Adam or have the
Gospel preached to them. Nor would there be any inconsistency with the
poet’s own description of our hemisphere as that covered by “la gran
secca,”[404] or with the voyage of Ulysses, on which he saw no land but
the Mountain of Purgatory; for he sailed south-west, not due south, and
the “mondo senza gente”[405] was “diretro al Sol.”[406]

------------------------------------------------------------------------
[404] “The great dry land.” _Inf._ xxxiv. 113.

[405] “The unpeopled world.” _Inf._ xxvi. 117.

[406] “Behind the sun.” _Ibid._
------------------------------------------------------------------------

The indications are as follows:—

(1) The passage quoted above, where it is said that the equator
“divides the uncovered land from the ocean”[407] is ambiguous in the
original, and might mean “divides the land uncovered by Ocean.”

------------------------------------------------------------------------
[407] _Conv._ III. v. 117, 118.
------------------------------------------------------------------------

(2) Shortly before, he has distinctly admitted that there is some land
in the southern hemisphere, by saying that the north celestial pole is
visible to _nearly all_ the land not covered by sea, and the south is
hidden from _nearly all_ of it. The first is true in any case, since
though the pole is theoretically visible as far as the equator, it is
often hidden by mist or rising land on the northern horizon; but unless
the second “nearly” has been added by a (somewhat natural) mistake of a
copyist, it can only apply to lands in the southern hemisphere.[408]

------------------------------------------------------------------------
[408] Refraction makes the pole visible a little before one reaches the
equator, but such refinements need not be considered in dealing with a
popular work like the _Convivio_.
------------------------------------------------------------------------

(3) There is a stanza in _Canzone XV._ which suggests that Dante
believed Ethiopia to be on the south side of the equator. Classical
and mediæval cosmographers had very vague ideas about the extent and
position of this country. Dante describes a wind raised in its deserts
by the sun, which _now_ is heating it (implying the time of summer?);
but the same wind, crossing the sea to Europe, darkens all _this_
hemisphere, bringing clouds which fall in snow.

    “Levasi della rena d’Etiopia
      Un vento pellegrin, che l’ aer turba,
      Per la spera del sol, ch’ or la riscalda,
      E passa il mare, onde n’adduce copia
      Di nebbia tal, che s’ altro non la sturba
      Questo emisperio chiude tutto, e salda;
      E poi si solve, e cade in bianca falda
      Di fredda neve, ed in noiosa pioggia.”[409]

------------------------------------------------------------------------
[409]
    “There riseth up from Ethiopia’s sands
    A wind from far-off clime which rends the air,
    Through the sun’s orb that heats it with its ray.
    The sea it crosses; thence, o’er all the lands
    Such clouds it brings that but for wind more fair
    O’er all our hemisphere ’twould hold its sway;
    And then it breaks and falls in whitest spray
    Of frozen snow and pestilential showers.”
                       _Canz._ xv. 14-21. (_Plumptre_).
------------------------------------------------------------------------

However, it may be said that “or la riscalda”[410] means merely
that it is always hot in the tropics, even when we have winter, and
that “questo emisperio”[411] cannot possibly mean the whole of the
terrestrial northern hemisphere from equator to pole, but simply
describes the appearance of the hemispherical sky,[412] completely
covered with cloud.

These doubtful passages are not strong enough to set against the
explicit statement in the _Quæstio_ that the habitable earth extends
from the equator to the Arctic circle and no further.[413] Letters and
reports from missionaries and traders, none of them scientific, did not
shake Dante’s faith in the limits laid down by Ptolemy and Alfraganus.
His geography was utterly wrong, but his astronomy was right; and
therefore, although he had no idea of what he would see on our globe in
untravelled latitudes, he knew exactly, and has described vividly, what
he would see in the sunny sky.

------------------------------------------------------------------------
[410] “Now heats it.”

[411] “This hemisphere.”

[412] Just as in _Par._ xxviii. 80.

[413] _Qu._ xix. 53-57, and repeated in xxi. 36-40.
------------------------------------------------------------------------


9. CELESTIAL PHENOMENA AND TIME.

The foregoing quotations have shown how well Dante understood
the changing appearances of the celestial phenomena as viewed
from different latitudes: it now remains to be seen what were his
conceptions of longitude.

A difference in longitude between two places makes no difference in the
stars, nor in the apparent paths of the heavenly bodies, but they come
to the meridian sooner in the more easterly place; and as it is the
meridian passage of the sun which determines local time, this will vary
in exact proportion to the distance east. When it is early morning in
England, it is noon in Burmah, and evening in Fiji. As Alfraganus had
observed (following Ptolemy), a celestial phenomenon such as a lunar
eclipse, which is caused by an actual darkening of the moon’s surface
when immersed in Earth’s shadow, is visible in every place where the
moon is above the horizon, though the local hour differs.

It is otherwise with a total solar eclipse, for this is only visible
from the very small portion of Earth on which the moon’s shadow falls
as she passes between us and the sun (see fig. 44); and as this shadow
moves on, owing to her own motion and the diurnal revolution combined,
the eclipse becomes visible successively from different parts of
the earth. Dante realized this when he quoted the argument of some
theologians that the miraculous three hours’ darkness described in
the Gospels could not have been caused by an eclipse of the sun, as
Aquinas and others had suggested, because it was visible all over the
earth at the same absolute time, that is, during the Crucifixion.[414]
Some said, he tells us, that the moon went back and placed herself
between us and the sun (for the moon at Passover time was always full,
and therefore opposite the sun), so that the sun’s light should not
come down (to us on the earth); others, that the sun hid itself, for
a corresponding eclipse was seen by Spaniards and Indians as well as
Jews.[415] Spaniards and Indians were supposed to live at the extreme
western and eastern limits of the habitable earth: they were 180° in
longitude, or 12 hours in time, apart, and Jerusalem was midway between
them. Therefore the sun would be visible to all, though only just
rising in India and just setting in Spain;[416] but it could not have
been an eclipse that darkened it to all at the same time.

------------------------------------------------------------------------
[414] _Luke_ xxiii. 44.

[415] _Par._ xxix. 97-102.

[416] Dante believed the death of Christ to have taken place when it
was noon in Jerusalem. _Conv._ IV. xxiii. 105-106.
------------------------------------------------------------------------

[Illustration: Fig. 44. Lunar and Solar Eclipses.]

This passage shows that Dante was entirely orthodox and conservative
in his geography, as far as longitude was concerned, and confirms us
in the conclusion that he was so also with regard to latitude, and was
not likely to accept contemporary evidence about lands south of the
equator, or stars unknown to Ptolemy. In the _Divine Comedy_ there are
several passages which refer to the same system, as for instance where
Night is described as covering the whole region from “the Shore” to
Morocco,[417] or where the time is stated to be noon on the Ganges,
sunrise at Jerusalem, and midnight in Spain.[418] And in the _Quæstio
de Aqua et Terra_ the system is thus clearly explained:—

    “As all these agree in believing [the naturalists,
    the astrologers, and the cosmographers], this
    habitable earth extends in longitude from Gades,
    which lies on the western boundaries of Hercules,
    as far as the mouths of the Ganges, as Orosius
    writes.[419] That longitude is such that at the
    equinox the sun is setting upon those who are at
    one of these boundaries, while it is rising upon
    those who are at the other, as astrologers have
    discovered by eclipses of the moon. Therefore the
    aforesaid boundaries must be 180 degrees distant in
    longitude, which is half the distance of the whole
    circumference.”[420]

------------------------------------------------------------------------
[417] _Purg._ iv. 137-139.

[418] _Purg._ xxvii. 1-5.

[419] Orosius says: “Europæ in Hispania occidentalis oceanus termino
est, maxime ubi apud Gades insulas Herculis columnæ visuntur.... Asia
ad mediam frontem orientis habet in oceano Eoo ostia fluminis Gangis.”

[420] _Qu._ xix. 38-52.
------------------------------------------------------------------------

Gades is not the city of Cadiz, but two islands (the “Gades Insulæ” of
Orosius), on which Hercules was said to have set up his Pillars, as a
sign that no one should venture further; and they were thought to lie
in the mouth of what we call the Straits of Gibraltar:[421]—

------------------------------------------------------------------------
[421] Moore, _Studies in Dante_ iii. p. 124.
------------------------------------------------------------------------

                    “quella foce stretta,
    Ov’ Ercule segnò li suoi riguardi,
    Acciochè l’uom più oltre non si metta.”[422]

------------------------------------------------------------------------
[422]
    “The strait pass, where Hercules ordained
    The boundaries not to be o’erstepped by man.”
                           _Inf._ xxvi. 107-109. (_Carey_).
------------------------------------------------------------------------

Through these Ulysses sailed, never to return.[423]

------------------------------------------------------------------------
[423] _Inf._ xxvi. 106-142.
------------------------------------------------------------------------

It is difficult to believe that a lunar eclipse had ever been observed
simultaneously, and the local time compared, on the Ganges and at
Gibraltar, as the above quotation from the _Quæstio_ declares: and if
it had been, the astrologers, the cosmographers, and the naturalists
would have found out that they were greatly mistaken, for the distance
is little more than half what they thought. All that Ptolemy had said
was that this was the right method for calculating longitudes, and he
gave as an example an eclipse which had been seen at Arbela at the
fifth hour and at Carthage at the second hour.[424] It was, in fact, an
excellent method, and the only one before the day of chronographs and
telegraphs; and it seems to have been assumed that Ptolemy’s guess of
180° for the extent in longitude of the inhabited earth was based upon
it.

------------------------------------------------------------------------
[424] _Ptolemy’s Geography_, Bk. I.
------------------------------------------------------------------------

Then this 180° was considered, in the Middle Ages, as divided into two
equal parts, the western half containing Europe and Africa, the eastern
containing Asia. On the western front of Asia lay Jerusalem, thus
holding the central position in the inhabited earth which was thought
to be her right, on the authority of certain Scripture texts, as we
saw.[425] This gave the Mediterranean a length of 90°, which of course
is vastly too great. Even Ptolemy had only estimated it at 62°, and the
Alfonsine Tables made it 52°, while the true distance is only about 42°.

------------------------------------------------------------------------
[425] See p. 176.
------------------------------------------------------------------------

Latitude, however, was much more easily measured than longitude, for
it was only necessary to take the height of the pole star above the
horizon with an astrolabe; and the latitude of Jerusalem is really
just about midway between the supposed limits of the habitable earth,
the equator and arctic circle, for it is nearly 32° north.

Some daring spirits ventured to suggest that the dry land stretched
much further round the globe than was commonly supposed, so that one
might sail from Spain to Asia in quite a short time, and they sheltered
themselves behind the great names of Aristotle, Seneca, Pliny, and
Esdras.[426] Albertus Magnus quotes Aristotle to this effect, although
in another part of the same book (his _De Cælo et Mundo_), he repeats
the usual phrase about the habitable Earth being all contained within
one of the northern quadrants of earth. Roger Bacon expresses himself
more boldly, and it is possible that he was impressed by the long
journey of the Franciscan friar Rubruquis, on his mission to Central
Asia, from St. Louis of France to the Emperor of the Mongols. Besides
relating the story of this journey, Bacon speaks of men who were known
to live in tropical Taprobane (Ceylon), and if there, why not also
south of Capricorn? There may be delightful countries there, since it
is the better and nobler part of the world, as Aristotle and Averroës
taught.

Moreover, Dante’s own countryman, the learned Pietro d’Abano,
maintained that there are habitable lands on, and even beyond the
equator, and did not hesitate to quote conversations with Marco Polo
as evidence, although this “most extensive traveller and most diligent
enquirer” was accounted a romancer by most of his contemporaries. Had
not Messer Marco told him that in islands south of the equator he had
seen not only great rams with coarse stiff wool like the bristles of
pigs, but human beings?[427]

------------------------------------------------------------------------
[426] _Esdras_ II. vi. 42.

[427] Beazley, _Dawn of Geography_ iii. 28, 29.
------------------------------------------------------------------------

Roger Bacon was banished from Oxford on a charge of heresy and
witchcraft: Pietro d’Abano escaped the Inquisition by dying, in 1316.
Men such as these belonged to the new age that was coming, the age
that would throw away the old lesson-books, and begin to discover for
itself—and they suffered in consequence. Dante belonged heart and soul
to his own era, and clung passionately to its ideals and traditions.
For him the Ganges still flowed into the all-surrounding ocean on
the east coast of Asia, 90 degrees from Jerusalem, as Orosius had
pictured it, and there is not the faintest echo in his writings of the
voyages of his countrymen, Corvino and his bishops, or Polo and his
companions,[428] between “Greater India” and “Zayton” (Amoy harbour),
although they surely must have recognized, when they praised the great
rivers of China, that these flowed into a sea many days’ journey
beyond that into which the Ganges rolled its waters. Nor is there, on
the other hand, any hint of the monstrous races with which Dark-Age
superstition had peopled the remote regions of the earth, although
they were regularly represented on the maps of that time. It is true
that the “portolani,” or handy charts, of which the earliest known
date from Dante’s life-time, showed none of these things, but depicted
the coast-lands of the Mediterranean and Black Seas with marvellous
accuracy: but they were only for pilots and merchant captains, and
had nothing to do with scholars. The maps Dante would see were hung
on church or monastery walls, or illustrated learned books; and the
mappe-monde of Cardinal Heinrich of Mainz may be taken as typical of
them all. It much resembles our great Hereford Map of the World, and
was probably copied from the same original design.

------------------------------------------------------------------------
[428] Corvino and Marco Polo made the voyage in the same year, 1292,
but in reverse directions.
------------------------------------------------------------------------

It is two hundred years older than Dante, but so stationary was
geography throughout the Middle Ages that it might have been executed
in his day, or, except for a few details, several centuries earlier.

Mediæval maps are as fascinating as a fairy tale, which indeed they
much resemble. The shape is conventional, and not supposed to represent
the true shape of the habitable earth; it is sometimes circular,
sometimes quadrilateral, occasionally oval, as in the present instance.
The east is here, as usual, at the top, and there we see the Paradise
of Adam and Eve, and close beside it, to the north, the River Ganges,
flowing into the great ocean which surrounds all the land. At the
opposite or western extremity are the Pillars of Hercules, which two
angels appear to be guarding. In the centre, but not so exactly or
conspicuously central as in some other maps, we find “Hierusalem.”
Along the south is the long narrow continent of Africa, with the Atlas
and Ethiopian mountains; and the Nile, rising far in the south-west,
after mysterious submergences and reappearances, finally flows into
the Mediterranean, past the pictured Pyramids, here strangely called
(according to Dark-Age myth) the Barns of Joseph. In the north another
Angel points to the country where dwell the Gog-Magogs, and not far
off are the lands of the Hyperboreans, here described as untroubled
by disease or discord, of the “most wicked” Gryphons, and of the
Dog-headed folk, adjoining the Arctic Ocean.

Italy is a very large country, roughly triangular, and in the
Mediterranean to the south lie Sicily, the whirlpool Charybdis, the
rock Scylla, Sardinia, Corsica, and other islands. Rome is figured as a
battlemented city, about halfway between Jerusalem and the Pillars of
Hercules.

[Illustration: MAP OF THE WORLD BY HEINRICH OF MAINZ, ABOUT A.D. 1110.

_To face p. 344._

_Reproduced by permission from Beazley’s “Dawn of Modern Geography.”_]

This is where Dante also places the imperial city, for in his system
it is about 45°, or 3 hours, east of Gades and west of Jerusalem. He
tells us in one place that it was vespers in Naples when the sun rose
in Purgatory,[429] and in another that when it was vespers or three
o’clock in the afternoon in Purgatory, it was midnight “here”[430]
which may mean Florence or Italy in general; both these statements
indicate a difference of nine hours or 135° between Italy and
Purgatory. Purgatory in the _Divine Comedy_ is exactly antipodal to
Jerusalem, and therefore twelve hours distant in time;[431] and for
the sake of his allegory Dante has so far departed from tradition as
to place the Earthly Paradise here also.[432] These five places may
therefore be diagramatically represented thus:—

------------------------------------------------------------------------
[429] _Purg._ iii. 25.

[430] _Purg._ xv. 1-6.

[431] _Purg._ iv. 68-71; xxvii. 1-5.

[432] _Purg._ xxviii. 142. Opinions differed as to its exact site, and
some placed it in the ocean beyond the eastern limit of the habitable
earth. In _V. E._ I. viii. 6-10, Dante says that the root of the human
race was planted in eastern lands, but this refers to Adam’s home after
the expulsion from Paradise.
------------------------------------------------------------------------

         +---------------------------------------------------------+
          EARLY <----------------  TIME ----------------------> LATE
          12 hours    6hrs.   3hrs.          6hrs.    12 hours
          ---+----------+-------+----+---------+-----------+--------

          Purgatory   Gades  Italy Jerusalem  Ganes   Purgatory

          ---+----------+-------+----+---------+-----------+--------
          180°      90°       45°    0°        90°         180°
          WEST <--------------- LONGITUDE --------------------> EAST
         +---------------------------------------------------------+

With this key, Dante’s fondness for describing the time at one place by
mentioning one of the others need be no stumbling-block, as it is to
many readers.

The fact is that though Dante had none of our opportunities for
changing time-reckoning by long journeys, nor for communicating with
friends at the other side of the world, who wake while we sleep, the
marvellous daily revolution of the skies had a fascination for him,
and he delighted to picture a glorious sunrise taking place in one
country while in another it was high noon, or the middle of the night.
Thus, the beautiful description of the stars fading in the growing
light of dawn, which we quoted above, is preceded by a picture of the
sun glowing on the meridian some 6000 miles away (rather more than a
quarter the circumference of the globe), while with us Earth’s shadow
has sunk almost to a level plane.[433]

Again, Folco of Marseilles, when describing his birthplace, says that
the greatest of all the seas (the Mediterranean) except the ocean which
encircles all the habitable earth, stretches so far against the sun
(i.e. from west to east), that the line of sky which is on its horizon
at one end is on its meridian at the other.[434] If the sun were
seen just rising on the eastern horizon at Gades, it would be on the
meridian at Jerusalem and the time would there be noon.

------------------------------------------------------------------------
[433] _Par._ xxx. 1-3.

[434] _Par._ ix. 82-87.
------------------------------------------------------------------------

Dante’s hours are always reckoned from sunrise, and they are the
“temporary” or Church hours. He defines both kinds in the _Convivio_.
The same lines of his Ode which provided him with a text whereon to
discourse of the sun’s movements, give him occasion to treat of the
division of each day into hours, thus:—

    “I say that the sun, in circling round the world,
    _ne’er beholdeth aught so noble as this lady_, from
    which it follows that she is, as the words affirm,
    the most noble of all the things on which the sun
    shines. And I say _in that hour_, etc. Wherefore
    we must know that the _hour_ is understood in
    two senses by astrologers. One sense is employed
    when they assign twenty-four hours to the day and
    night, that is, twelve to the day and twelve to the
    night, however long or short the day may be. And
    these hours become short or long in the day and in
    the night, according as the day and night wax and
    wane. And the Church uses hours in this sense when
    she speaks of Prime, Tierce, Sext, and None; and
    these are called temporal hours. The other sense is
    employed when, of the twenty-four hours alloted to
    the day and night, the day has sometimes fifteen
    and the night nine, and sometimes the night has
    sixteen and the day eight assigned to it, according
    as the day and the night wax and wane; and these
    are called equal hours. And at the equinox these
    latter are always one and the same with those which
    are called temporal; for it must needs be so when
    the day and the night are of the same length.”[435]

The choice of these two examples of unequal days and nights seems to be
another instance of Dante’s dependence upon Alfraganus, for in Chapter
VIII. of the _Elementa Astronomica_ we read that the middle of the
seventh climate (in which the inequality is greatest) has a longest day
of 16 hours, and the middle of the fifth, of 15 hours; and in chapter
IX. we find that Magna Roma is situated in the fifth climate.

In the fourth treatise of the _Convivio_, Dante returns to the same
subject, and enters into further detail about Church hours and
divisions of the day.[436] Our lives, like the arch of heaven which is
always above us, consist of a rise and a decline, with a culminating
point, and this point he fixes as normally reached at a man’s 35th
year, as Ristoro had also done.[437] In the same way the day rises and
declines, and culminates at the sixth hour; and it is the most noble
hour of the day and the most virtuous (in the old Latin sense of virtue
as strength, efficacy).

------------------------------------------------------------------------
[435] _Conv._ III. vi. 7-32.

[436] _Conv._ IV. xxiii. 50 to end.

[437] _Comp. del Mondo_, I. xxii.
    “La sesta ora, cioè il mezzo del dì, è la più
     nobile di tutto il dì, e la più vertuosa.”[438]

[438] “The sixth hour, that is, the middle of the day, is the most
noble of all the day, and the most virtuous.”
------------------------------------------------------------------------

This means the whole of the sixth hour (as we should say, from 11 to
12 o’clock): the beginning of the seventh hour is the exact moment of
noon, after which the day begins to decline. It was for this reason,
Dante believes, that Christ chose to die during the sixth hour,[439]
and during his 34th year, for then the day and his human life were both
at their culmination, and had not begun to decline.

------------------------------------------------------------------------
[439] _Luke_ xxiii. 44-46. Dante understands this to mean that death
took place at about the sixth hour, not the ninth.
------------------------------------------------------------------------

There was some difference in the methods of reckoning the hours for
Church offices, but Dante tells in this same passage which of them he
considered right, and he follows it consistently in his works. The
Church day was divided into four parts, viz.:—

                                                     At the equinox=
    Tierce,   Sunrise to the end of the third hour   6 to 9 a.m.
    Sext,     Fourth to end of sixth hour            9 a.m. to 12 noon
    Nones,    Seventh to end of ninth                12 noon to 3 p.m.
    Vespers,  Tenth hour to sunset                   3 to 6 p.m.

Two of the Church offices were to be said at the beginning, and one at
the end, of these periods, as follows:—

    Tierce,   at the end          _i.e._ 9 a.m. at the equinox.
    Nones,    at the beginning    _i.e._ 12 noon.
    Vespers,    ”       ”         _i.e._ 3 p.m. at the equinox.

Thus sext is omitted altogether, and Dante says that the reason for
the arrangement is to approximate in every case to that hour which is
the noblest of the whole day, the sixth.

Mid-tierce was halfway through the period from sunrise to the end of
the third hour, that is, 7.30 a.m. at the time of the equinox; and
mid-nones and mid-vespers were counted in the same way.

As an instance of reckoning hours by the sun, we may quote the reply of
Adam when Dante desired to know how long time he had spent in Eden:

    “Dalla prim’ ora a quella che seconda,
    Come il sol muta quadra, l’ora sesta.”[440]

------------------------------------------------------------------------
[440]
    “From the first hour to that which cometh next
    (As the sun changes quarter) to the sixth.”
                          _Par._ xxvi. 141-142. (_Carey_).
------------------------------------------------------------------------

Just as the time of day may be told, if one is accustomed to watch the
sun, by noting how much of the daily course has been run, so the time
of day or night (according to her phase) may be told by the moon; only
with her we must take into consideration the rapid and variable motion
eastwards in the zodiac. Alfraganus says that her _mean_ daily motion
in longitude is 13° and nearly 11 minutes,[441] but that a small amount
must be added or subtracted every day in order to find her true motion.
As a clock, therefore, for use in daily life, she leaves much to be
desired. This daily motion makes her fall constantly behind the sun, so
that she loses time every day, and not even the same amount of time;
for though she crosses the meridian on an average 50½ minutes later
each day, the interval is sometimes only 38 minutes and sometimes as
much as 66 minutes. And her times of setting and rising are even more
variable.

------------------------------------------------------------------------
[441] It is easily seen that this is correct, if we divide the 360° of
the moon’s path through the zodiac by the 27 days and eight hours in
which she traverses it, and returns to the same star. Brunetto Latini
says “La lune s’esloigne _dou Soleil_ chascun jor xiii degrez po s’en
faut,” but he is wrong, having apparently forgotten that the sun is
also moving in the same direction, at the average rate of nearly 1°
daily.
------------------------------------------------------------------------

This is easily understood if we remember how much the sun’s time
of setting varies throughout the year, according to the part of the
zodiac in which he is travelling, and consider that what the sun does
in a year the moon does in a month. And in her case the effect is
sometimes exaggerated, sometimes diminished, for her path in the zodiac
is inclined to the sun’s path; moreover, her greatest departure from
it to north and south takes place in different parts of the zodiac at
different times. These facts were well known to Ptolemy and to mediæval
astronomers, and everyone who watches the moon must have noticed how
variable are the intervals between one moonrise or one moonset and the
next.

The extent of variability also depends upon our latitude (just as with
sunrises and sunsets); and in Florence the retardation in one day may
sometimes be only twenty minutes, sometimes an hour and twenty minutes.
The difference would be less in Dante’s Purgatory, since this was in
latitude 32° south, and the intervals between moonset and moonset
become less variable in length as we approach the equator, just as the
days become less unequal all the year round. Still, they would vary
a good deal, so we must conclude that Dante only means to indicate
the time quite roughly when he uses the moon as a clock. As a matter
of fact, he seldom does so in the _Divine Comedy_ without giving us
another clue to the time as well.

These passages all belong to a most interesting series of time
indications, which we may now proceed to examine.




_VI. DANTE’S JOURNEY THROUGH THE THREE REALMS: INDICATIONS OF TIME AND
DIRECTION BY MEANS OF THE SKIES._


1. TIME REFERENCES IN THE DIVINE COMEDY.

The plan of the universe through which Dante feigns himself to have
journeyed is familiar to all readers of the _Divine Comedy_. Hell,
as the Fathers taught, was a subterranean cavity, and Dante pictures
it as an inverted cone, whose apex reaches the exact centre of Earth
and therefore of the universe. It is situated vertically underneath
Jerusalem, the centre of the inhabited Earth. He departs from the
Fathers, however, in removing Purgatory from these dim regions, and
placing it on an island in the midst of the ocean of the uninhabited
hemisphere, exactly at the antipodes of Jerusalem. On this island rises
a mountain whose immensely lofty summit reaches the upper regions of
the atmosphere, and upon the summit is the Eden of our first parents.
This original conception is an extraordinary gain, both from the
artistic and the allegorical points of view; and it is in harmony
with the idea of Aristotle, and of many mediæval writers, that the
southern hemisphere was the “nobler” part of Earth. Here, then, man was
permitted to dwell before the Fall, and hither come repentant souls,
saved from Hell, but not yet pure enough to enter Heaven. Paradise
consists of all the spheres of mediæval astronomy, and the poet
rises from one to another until he finally reaches the all-embracing
Empyrean, where his vision ends.

Nowhere does he describe this scheme in full, but it was evidently
clear in his own mind, and by following him step by step in his journey
it is easily reconstructed, and is represented in the accompanying
diagram.

In the same way he never states how long a time he spent on this
visionary journey, yet this also he had definitely determined, and in
each Cantica he refers once to the period of time alloted to each realm.

In the last Circle but one of the Inferno, he is warned by Virgil
that the time allowed is drawing to a close;[442] in the last but one
of the Purgatorio Virgil urges him to make the best use of the time
appointed;[443] and in the Paradiso, just before the final vision, St.
Bernard tells him that the time of his trance is nearly over.[444]

------------------------------------------------------------------------
[442] _Inf._ xxix. 11.

[443] _Purg._ xxiii. 5, 6.

[444] _Par._ xxxii. 139.
------------------------------------------------------------------------

In the first Canto, which is introductory to the whole _Commedia_,
he mentions the time at which he assumes that his vision began. It
was “nel mezzo del cammin di nostra vita,”[445] which may mean simply
that he was middle-aged, or comparing it with the passage in the
_Convivio_ quoted earlier (see p. 347), we may suppose it to mean
that he was exactly in his 35th year. The season was spring—“la dolce
stagione,”[446] and when night was over the sun rose among those stars
which were with him at the Creation, which was believed to have taken
place at the vernal equinox some sixty-five centuries before.

------------------------------------------------------------------------
[445] “Midway in the journey of our life.” _Inf._ i. 1.

[446] “The sweet season.” _Inf._ i. 43.

    “Il Sol montava su con quelle stelle
        Ch’ eran con lui quando l’Amor Divino
        Mosse da prima quelle cose belle.”[447]

[447]
    “Aloft the sun ascended with those stars
      That with him rose when Love Divine first moved
      Those its fair works.”
                               _Inf._ i. 38-40. (_Carey_).
------------------------------------------------------------------------

[Illustration: Fig. 45. The Universe of Dante.]

The expression “quelle stelle,”[448] however, shows us that Dante
does not intend to be pedantically accurate, which would indeed be
inartistic in a poem. He speaks several times of the supposed slow
motion of the star sphere,[449] and although he never mentions its
effect in shifting the place of the equinox continually among the
stars, we can hardly imagine that he failed to understand this. He knew
quite well, therefore, that the stars which accompanied the sun in
that first springtime of the world could not be the same stars which
rose with him now. But astronomers had agreed to call the part of the
sky which contains the vernal equinox by its old name, and it would be
exceedingly tiresome if he were to distinguish, every time he mentioned
them, between the zodiacal constellations and the zodiacal signs; there
shall be no occasion, therefore, to stop and consider which he means,
and no ambiguity: he assumes once for all that they always have been
and always are identical, that the “first point of Aries” or vernal
equinox is now and always at the beginning of the constellation Aries.
To this assumption he is consistent throughout.

------------------------------------------------------------------------
[448] “Those stars.”

[449] _Purg._ xi. 108; _Conv._ II. xv. 12-14.
------------------------------------------------------------------------

Another important point to notice is that, since it is the time of
the equinox, there is no difference between “temporary” and “equal”
hours.[450] Days and nights are of equal length; sunrise and sunset
are nearly at 6 a.m. and 6 p.m., according to our modern method
of reckoning.[451] In this way also, and without any sacrifice of
astronomical accuracy, the poet has simplified his time references for
his readers.

------------------------------------------------------------------------
[450] _Conv._ III. vi. 28-30.

[451] On the day of the spring equinox the sun rises and sets a few
minutes after six o’clock, because we set our clocks not by the real
sun but the more convenient “mean sun.”
------------------------------------------------------------------------

We must observe, however, that the day is as uncertain as the year;
for, although it is certainly near the equinox, “quelle stelle” may
mean exactly the first point of Aries or only the constellation Aries
in general. From this Canto alone, therefore, we cannot be sure of the
exact date.

From other allusions of various kinds, scattered throughout the
_Divine Comedy_, we gather that Dante did intend a definite date to be
understood, but unfortunately the data by which he means to fix it are
themselves so ambiguous that commentators differ as to the day, the
month, and the year. The question has so direct a bearing on Dante’s
astronomy that we cannot shirk it; but for the present, leaving it
aside, let us deal merely with the hour, which is distinctly stated
from the first, and indicated in a number of passages so clearly that
readers with an elementary knowledge of the apparent movements of the
heavenly bodies can find little difficulty in following Virgil and
Dante through their journey, seeing exactly how many days it required,
and frequently at what hour of day or night they were in a particular
spot. If my readers are not now in possession of this elementary
knowledge, this book has been written in vain.

I give below a list of all the hour-indications, astronomical and
others, for the sake of clearness and completeness; but I omit for the
present those that indicate only the date, and merely call the days
the first, second, etc. These passages, though they are only to be
understood in a popular sense, prove quite as clearly as the elaborate
astronomical explanations in the _Convivio_ how deep an interest
Dante always took in astronomy; and a study of them shows that he had
carefully considered the positions of the heavenly bodies and their
movements during the progress of the action in his poem.

                     TIME REFERENCES IN THE DIVINE COMEDY

        Night. In the Forest. Moon full
        (see below, _Inf._ xx. 127-129, and _Purg._ xxiii. 118-121).

        “La notte ch’ i’ passai.”
                         _Inf._ i. 21.
                                           “The night that I had spent.”
        ----------------------------------------------------------------
        1st day. Just before sunrise.
        At the foot of the Hill.

       “Ma poi ch’ io fui al piè d’un colle giunto,
                 .  .  .  .  .
        Guardai in alto, e vidi le sue spalle
          Vestite già de’ raggi del pianeta
          Che mena dritto altrui per ogni calle.”
                              _Inf._ i. 13-18.

                           “But after I had reached a mountain’s foot,
                                          .  .  .  .  .  .
                            Upward I looked, and I beheld its shoulders
                              Vested already with that planet’s rays
                              Which leadeth others right by every road.”
        ----------------------------------------------------------------
        Sunrise 6 a.m.[452]
        Climbing the Hill.

        “Tempo era dal principio del mattino,
           E il sol montava su con quelle stelle
           Ch’eran con lui quando l’ Amor divino
         Mosse da prima quelle cose belle.”
                            _Inf._ i. 37-40.

                        “The time was the beginning of the morning,
                           And up the sun was mounting with those stars
                           That with him were, what time the Love Divine
                         At first in motion set those beautous things.”

------------------------------------------------------------------------
[452] The clock-hours in this column are not to be regarded as if taken
from a railway time-table! Sunrise is at 6 a.m. within a few minutes
only, for the reasons above stated, viz.: our clocks are regulated by
the “mean” sun, and it is not necessarily the exact day of the equinox
when the vision begins.
------------------------------------------------------------------------

        Evening twilight.
        At the Gate of Hell.

        “Lo giorno se n’andava, e l’ aer bruno....”
                                 _Inf._ ii. 1.

                              “Day was departing, and the brown air....”
        ----------------------------------------------------------------
        Midnight.
        Crossing the fourth circle.

        “Già ogni stella cade, che saliva
         Quando mi mossi.”
                  _Inf._ vii. 98, 99.

                             “Already sinks each star that was ascending
                              When I set out.”
        ----------------------------------------------------------------
        2nd day. About 2 hrs. before sunrise (4 a.m.)
        On the edge of the cliff, preparing to descend to the 7th
        circle.

        “I Pesci guizzan su per l’ orizzonta,
         E il Carro tutto sovra il Coro giace.”
                         _Inf._ xi. 113, 114.

                               “Quivering are the Fishes on the horizon,
                                And the Wain wholly over Caurus lies.”
        ----------------------------------------------------------------
        (Dante refers to the previous day.)
         In the 7th circle.

        “Mi smarri’ in una valle.
              .  .  .  .  .
         Pur ier mattina le volsi le spalle.”
                       _Inf._ xv. 50-52.

                              “I lost me in a valley.
                                  .  .  .  .  .
                               But yestermorn I turned my back upon it.”
        ----------------------------------------------------------------
        After sunrise, between 6 and 7 a.m.
        Leaving the 4th Pit of Circle VIII.
       (Virgil reminds Dante of the night before last, spent in the
        Forest.)

             “Già tiene il confine
          D’ ambedue gli emisperi e tocca l’ onda
          Sotto Sibilia Caino e le spine;
        E già iernotte fu la luna tonda;
          Ben ten dee ricordar, chè non ti nocque
          Alcuna volta per la selva fonda.”
                         _Inf._ xx. 124-129.

                               “... Already holds the confines
                       Of both the hemispheres, and under Seville
                       Touches the ocean-wave, Cain and the thorns;
                     And yesternight the moon was round already;
                       Thou shouldst remember well: it did not harm thee
                       From time to time within the forest deep.”
        ----------------------------------------------------------------
        7 a.m.
        On the bridge over the 5th Pit.

        “Ier, più oltre cinq’ ore che quest’ otta,
           Mille dugento con sessanta sei
           Anni compiè che qui la via fu rotta.”
                         _Inf._ xxi. 112-114.

                   “Yesterday, five hours later than this hour,
                      One thousand and two hundred sixty-six
                      Years were complete that here the way was broken.”
        ----------------------------------------------------------------
        About 1 p.m.
        Leaving the 9th Pit.

        “E già la Luna è sotto nostri piedi,
           Lo tempo è poco omai che n’è concesso.”
                         _Inf._ xxix. 10, 11.

                           “And now the moon is underneath our feet.
                              Henceforth the time allotted us is brief.”
        ----------------------------------------------------------------
        Nightfall.
        At the bottom of the world.

           “La notte risurge; ed oramai
        È da partir, chè tutto avem veduto.”
                  _Inf._ xxxiv. 68, 69.

                              “Night is reascending, and ’tis time
                            That we depart, for we have seen the whole.”
        ----------------------------------------------------------------
        3rd day. (no night intervening) 7.30 a.m.
        In the new hemisphere

        “Già il sole a mezza terza riede.”
                    _Inf._ xxxiv. 96.

                             “And now the sun to middle-tierce returns.”
        ----------------------------------------------------------------
        4th day. About an hour  before sunrise (5 a.m.).
        On the island of Purgatory.

        “E quindi uscimmo a riveder le stelle.”
                        _Inf._ xxxiv. 139.

                          “Thence we came forth to see again the stars.”

        “Lo bel pianeta che ad amar conforta
          Faceva tutto rider l’ oriente,
          Velando i Pesci ch’ erano in sua scorta.”
                             _Purg._ i. 19-21.

                         “The beauteous planet that to love incites
                            Was making all the orient to laugh,
                            Veiling the Fishes that were in her escort.”
        ----------------------------------------------------------------
        Dawn.

        “Lo sol vi mostrerà, che surge omai.”
                         _Purg._ i. 107.

                        “The sun, which now is rising, will direct you.”

        “L’ alba vinceva l’ ora mattutina.”
                         _Purg._ i. 115.

                              “The dawn was vanquishing the matin hour.”
        ----------------------------------------------------------------
        Sun just below east horizon.
        On the Shore of the Island.

        “Già era il sole all’ orizzonte giunto
           Lo cui meridian cerchio coperchia
           Jerusalem col suo più alto punto;
         E la notte, che opposita a lui cerchia,
           Uscia di Gange fuor con le bilance
           Che le caggion di man quando soperchia;
         Si che le bianche e le vermilie guance,
           Là dove io era, della bella Aurora,
           Per troppa etate divenivan rance.”
                             _Purg._ ii. 1-9.

                      “Already had the sun the horizon reached
                         Whose circle of meridian covers o’er
                         Jerusalem with its most lofty point;
                       And night, that opposite to him revolves,
                         Was issuing forth from Ganges, with the scales
                         That fall from out her hand when she exceedeth;
                       So that the white and the vermilion cheeks
                         Of beautiful Aurora, where I was,
                         By too great age were changing into orange.”
        ----------------------------------------------------------------
        Sun risen.

        “Da tutte parti saettava il giorno
           Lo sol, ch’avea con le saette conte
           Di mezzo il ciel cacciato il Capricorno.”
                             _Purg._ ii. 55-57.

                     “On every side was darting forth the day
                        The sun, who had with his resplendent shafts
                        From the mid-heaven chased forth the Capricorn.”
        ----------------------------------------------------------------
        Soon after sunrise.
        Walking westward, towards the Mountain of Purgatory.

        “Lo sol che retro fiammeggiava roggio.”
                          _Purg._ iii. 16.

                             “The sun that in our rear was flaming red.”
        ----------------------------------------------------------------
        Shortly after 6 a.m. (3 p.m. in Italy).

        “Vespero è già colà dov’ è sepolto
           Lo corpo dentro al quale io facea ombra.”
                          _Purg._ iii. 25, 26.

                            “’Tis vespers there already where is buried
                                 The body within which I cast a shadow.”
        ----------------------------------------------------------------
        About 9.30 a.m.
        At the foot of the Mountain.

        “Ben cinquanta gradi salito era
         Lo sole.”
                _Purg._ iv. 15, 16.

                                        “Fifty full degrees uprisen was
                                           The sun.”
        ----------------------------------------------------------------
        Midday.
        On a ledge of the Mountain (Anti-purgatory).

                      “Vedi ch’è tocco
        Meridian dal sole, e dalla riva.
        Copre la notte già col piè Morrocco.”
                   _Purg._ iv. 137-139.

                                              “See, the sun has touched
                                  Meridian, and from the shore the night
                                  Covers already with her foot Morocco.”
        ----------------------------------------------------------------
        Afternoon.
        Climbing the eastern slope of the Mountain.

        “Vedi omai che il poggio l’ ombra getta.
                 .  .  .  .  .
         Prima che sii lassù tornar vedrai
           Colui che già si copre della costa,
           Sì che i suoi raggi tu romper non fai.”
                          _Purg._ vi. 51-57.

                          “See, e’en now the hill a shadow casts.
                                   .  .  .  .  .
                           Ere thou art up there, thou shalt see return
                             Him, who now hides himself behind the hill,
                             So that thou dost not interrupt his rays.”
        ----------------------------------------------------------------
        Evening.

        “Vedi già come dichina il giorno.”
                    _Purg._ vii. 43.

                                     “See already how the day declines.”
        ----------------------------------------------------------------
        Sunset (6 p.m.).
        In the Flowery Valley, on the Mountain-side.

        “Era già l’ora che volge il disio
           Ai naviganti e intenerisce il core,
           Lo di ch’han detto ai dolci amici addio;
         E che lo nuovo peregrin d’ amore
           Punge, se ode squilla di lontano
           Che paia il giorno pianger che si more.”
                           _Purg._ viii. 1-6.

               “’Twas on the hour that turneth back desire
                   In those who sail the sea, and melts the heart,
                   The day they’ve said to their sweet friends farewell;
                And the new pilgrim penetrates with love,
                   If he doth hear from far away a bell
                That seemeth to deplore the dying day.”
        ----------------------------------------------------------------
        Evening twilight.

        “Tempo era già che l’ aer s’annerava.”
                       _Purg._ viii. 49.

                                 “Already now the air was growing dark.”
        ----------------------------------------------------------------
        (Dante refers to the morning of the same day.)

        “Per entro il lochi tristi
         Venni stamane.”
             _Purg._ viii. 58, 59.

                                       “Through the dismal places
                                        I came this morn.”
        ----------------------------------------------------------------
        Early night: about 7 p.m.

               “Le quattro chiare stelle
        Che vedevi staman, son di là basse,
        E queste son salite ov’ eran quelle.”
                   _Purg._ viii. 91-93.

                               “The four resplendent stars
                         Thou sawest this morning are down yonder low,
                         And these have mounted up to where those were.”
        ----------------------------------------------------------------
        Shortly before moonrise, between 8 and 9 p.m.

        “La concubina di Titone antico
           Già s’imbiancava al balco d’oriente,
           Fuor delle braccia del suo dolce amico;
         Di gemme la sua fronte era lucente,
           Poste in figura del freddo animale
           Che con la coda percote la gente;
         E la notte de’ passi con che sale
           Fatti avea due nel loco ov’ eravamo,
           E il terzo già chinava in giuso l’ ale.”
                             _Purg._ ix. 1-9.

                       “The concubine of old Tithonus now
                        Gleamed white upon the eastern balcony,
                        Forth from the arms of her sweet paramour;
                      With gems her forehead all relucent was,
                        Set in the shape of that cold animal
                        Which with its tail doth smite amain the people;
                      And of the steps with which she mounts the Night
                        Had taken two in that place where we were,
                        And now the third was bending down its wings.”
        ----------------------------------------------------------------
        5th day. Dawn.
        At the Gate of Purgatory.

        “Nell’ ora che comincia i tristi lai
           La rondinella presso alla mattina.”
                     _Purg._ ix. 13, 14.

                          “Just at the hour when her sad lay begins
                             The little swallow, near unto the morning.”

         (See also ix. 52 “nell’ alba che precede al giorno,”
          and ix. 59 “come il di fu chiaro.”)

                        (See also “At dawn, which doth precede the day.”
                         and “As day grew bright”).
        ----------------------------------------------------------------
        More than 2 hours after sunrise (after 8 a.m.).

        “Il sole er’ alto già più che due ore.“
                          _Purg._ ix. 44.

                         “And now the sun was more than two hours high.”
        ----------------------------------------------------------------
        About 9.30 a.m.
        On the 1st Cornice of the Mountain.

              “Pria lo scemo della luna
        Rigiunse al letto suo per rícorcarsi,
        Che noi fossimo fuori di quella cruna.”
                        _Purg._ x. 14-16.

                        “Sooner had the moon’s decreasing disc
                           Regained its bed to sink again to rest.
                           Than we were forth out of that needle’s eye.”
        ----------------------------------------------------------------
        12 noon.
        Ascent to the 2nd Cornice.

        “Più era già per noi del monte volto,
           E del cammin del sole assai più speso
           Che non stimava l’animo non sciolto.
               .  .  .  .  .
                  ... Vedi che torna
           Dal servigio del dì l’ancella sesta.”
                       _Purg._ xii. 73-81.

                       “More of the mount by us was now encompassed,
                          And far more spent the circuit of the sun,
                          Than had the mind preoccupied imagined.
                              .  .  .  .  .
                               ... Lo, returning is
                          From service of the day the sixth handmaiden.”
        ----------------------------------------------------------------
        3 p.m. (midnight in Italy).
        Ascent to the 3rd Cornice.

        “Quanto tra l‘ultimar dell’ ora terza
          E il principio del dì par della spera
          Che sempre a guisa di fanciullo scherza,
        Tanto pareva già in ver la sera
          Essere al sol del suo corso rimaso;
          Vespero là, e qui mezza notte era.
        E i raggi ne ferian per mezzo il naso,
          Perchè per noi girato era si il monte,
          Che già dritti andavamo in ver l’occaso.”
                             _Purg._ xv. 1-9.

                   “As much as ’twixt the close of the third hour
                      And dawn of day appeareth of that sphere
                      Which aye in fashion of a child is playing,
                    So much, it now appeared, towards the night
                      Was of his course remaining to the sun;
                      There it was evening, and ’twas midnight here.
                    And the rays smote the middle of our faces,
                      Because by us the mount was so encircled,
                      That straight towards the west we now were going.”
        ----------------------------------------------------------------
        Evening.
        On the 3rd Cornice.

        “Noi andavam per lo vespero, attenti
           Oltre, quanto potean gli occhi allungarsi
           Contra i raggi serotini e lucenti.“
                           _Purg._ xv. 139-141.

                          “We passed along athwart the twilight, peering
                             Forward, as far as ever eye could stretch
                             Against the sunbeams serotine and lucent.”
        ----------------------------------------------------------------
        Sunset at sea-level, 6 p.m.

                                  “Io rividi
        Lo sole in pria, che già nel corcare era.”
                          _Purg_ xvii. 8, 9.

                                                      “I saw again
                            The sun at first, that was already setting.”
        ----------------------------------------------------------------

        On the 3rd Cornice.

        “I raggi, morti già, nei bassi lidi.“
                      _Purg._ xvii. 12.

                                  “Rays already dead on the low shores.”
        ----------------------------------------------------------------

        Ascent to the 4th Cornice.

        “Procacciam di salir pria che s’abbui.”
                        _Purg._ xvii. 62.

                          “Let us make haste to mount ere it grow dark.”
        ----------------------------------------------------------------
        Sunset on the Mountain, shortly after 6 p.m.
        On the 4th Cornice.

        “Già eran sopra noi tanto levati
           Gli ultimi raggi che la notte segue,
           Che le stelle apparivan da più lati.”
                      _Purg._ xvii. 70-72.

                         “Already over us were so uplifted
                            The latest sunbeams which the night pursues,
                            That upon many sides the stars appeared.”
        ----------------------------------------------------------------
        Towards midnight.

        “La luna, quasi a mezza notte tarda,
           Facea le stelle a noi parer più rade,
           Fatta com’ un secchione che tutto arda;
         E correa contra il ciel per quelle strade
           Che il sole infiamma allor che quel da Roma
           Tra i Sardi e i Corsi il vede quando cade.”
                       _Purg._ xviii. 76-81.

                     “The moon, belated almost unto midnight,[453]
                         Now made the stars appear to us more rare,
                         Formed like a bucket that is all ablaze;
                      And counter to the heavens ran through those paths
                         Which the sun sets aflame when he of Rome
                         Sees it ’twixt Sardes and Corsicans go down.”

------------------------------------------------------------------------
[453] Or “almost at late midnight.”
------------------------------------------------------------------------

        6th day. Nearly 2 hours before sunrise, about 4 a.m.
        On the 4th Cornice.

        “Nell’ ora che non può il calor diurno
           Intepidar più il freddo della luna,
           Vinto da terra, o talor da Saturno;
         Quando i geomanti lor Maggior Fortuna
           Veggiono in oriente, innanzi all’ alba,
         Surger per via che poco le sta bruno.”
                        _Purg._ xix. 1-6.

                        “It was the hour when the diurnal heat
                            No more can warm the coldness of the moon,
                            Vanquished by Earth, or peradventure Saturn;
                         When geomancers their Fortuna Major
                            See in the orient, before the dawn,
                            Rise by a path that long remains not dim.”
        ----------------------------------------------------------------
        Early morning.
        Ascent to 5th Cornice.

        “Su mi levai, e tutti eran già, pieni
           Dell’ alto dì i giron del sacro monte,
           Ed andavam col sol nuovo alle reni.”
                         _Purg._ xix. 37-39.

                         “I rose, and full already of high day
                            Were all the circles of the sacred mountain,
                            And with the new sun at our back we went.”
        ----------------------------------------------------------------
        About 10 a.m.
        On the 6th Cornice.

        “E già le quattro ancelle eran del giorno
           Rimase addietro, e la quinta era al temo,
           Drizzando pure in su l’ ardente corno.”
                         _Purg._ xxii. 118-120.

                        “And four handmaidens of the day already
                           Were left behind, and at the pole the fifth
                           Was pointing upwards still its burning horn.”

        (Dante refers to “the other day” when he began the journey.)

        “Di quella vita mi volse costui
           Che mi va innanzi, l’ altr’ ier, quando tonda
           Vi si mostrò la suora di colui—
         E il sol mostrai.”
                            _Purg._ xxiii. 118-121.

                          “Out of that life he turned me back who goes
                             In front of me, some days agone, when round
                             The sister of him yonder showed herself—
                           And to the sun I pointed.”
        ----------------------------------------------------------------
        Between 2 and 4 p.m.
        Ascent to the 7th Cornice.

        “Il sole avea lo cerchio di merigge
         Lasciato al Tauro, e la notte allo Scorpio.”
                             _Purg._ xxv. 2, 3.

                                 “The sun bad his meridian circle
                                  To Taurus left, and Night to Scorpio.”
        ----------------------------------------------------------------
        Evening.
        On the 7th Cornice, west side of the Mountain.

        “Feriami il sole sull’ omero destro,
           Che già, raggiando, tutto l’ occidente
           Mutava in bianco aspetto di cilestro.”
                         _Purg._ xxvi. 4-6.

                           “On the right shoulder smote me now the sun,
                              That, raying out, already the whole west
                              Changed from its azure aspect into white.”
        ----------------------------------------------------------------
        Sunset at sea-level, 6 p.m.
        About to cross the zone of fire.

        “Sì come quando i primi raggi vibra
           La dove il suo Fattore il sangue sparse,
           Cadendo Ibero sotto l’ alta Libra,
         E l’ onde in Gange da nona riarse,
           Sì stava il sole; onde il giorno sen giva.”
                             _Purg._ xxvii. 1-5.

                      “As when he vibrates forth his earliest rays
                         In regions where his Maker shed his blood,
                         The Ebro falling under lofty Libra,
                       And waters in the Ganges burnt with noon,
                         So stood the sun; hence was the day departing.”
        ----------------------------------------------------------------
        Sun about to set on the mountain heights.
        At the foot of the last stairway.

        “Lo sol sen va, soggiunse, e vien la sera.”
                           _Purg._ xxvii. 61.

                          “The sun departs, it added, and night cometh.”
        ----------------------------------------------------------------
        Sun sets.
        Climbing the last stairway.

                    “Io toglieva i raggi
        Dinanzi a me del sol ch’era già basso.
               .  .  .  .  .
        Il sol corcar, per l’ ombra che si spense
        Sentimmo.”
                       _Purg._ xxvii. 65-69.

                               “I cut off the rays
                             Before me of the sun, that now was low.
                                       .  .  .  .  .
                                By the vanished shadow the sun’s setting
                             Behind us we perceived.”
        ----------------------------------------------------------------
        Night.
        On the last stairway.

        “Vedev’ io le stelle.”
        _Purg._ xxvii. 89.

                                “I beheld the stars.”
        ----------------------------------------------------------------
        7th day. About 4 a.m.

        “Nell’ ora, credo, che dell’ oriente
           Prima raggiò nel monte Citerea.”
                 _Purg._ xxvii. 94, 95.

                           “It was the hour, I think, when from the east
                              First on the mountain Cytherea beamed.”
        ----------------------------------------------------------------
        Dawn.

        “E già per gli splendori antelucani
               .  .  .  .  .
         Le tenebre fuggian da tutti i lati.”
                _Purg._ xxvii. 109-112.

                                “And now before the antelucan splendours
                                       .  .  .  .  .
                                 The darkness fled away on every side.”
        ----------------------------------------------------------------
        Early morning.
        In the Earthly Paradise.

        “Vedi là il sol che in fronte ti riluce.”
                        _Purg_. xxvii. 133.

                         “Behold the sun that shines upon thy forehead.”

        “L’ ôre prime.”
               _Purg._ xxviii. 16.

                                           “The hours of prime.”
        ----------------------------------------------------------------
        Midday.
        By the fountain of Eunoë.

        “Teneva il sole il cerchio di merigge.”
                     _Purg._ xxxiii. 104.

                              “The sun was holding the meridian circle.”

        Ascent to Paradise.

        “Fatto avea di là mane e di qua sera
           Tal foce quasi, e tutto era là bianco
           Quello emisperio, e l’ altra parte nera.”
                              _Par._ i. 43-45.

                         “Almost that passage had made morning there
                            And evening here, and there was wholly white
                            That hemisphere, and black the other part.”
        ----------------------------------------------------------------
        8th day.
        A lapse of 6 hrs. since entering the 8th heaven.
                        (_Cf. Par._ xxii. 151-153).
        Sunset in Jerusalem (sunrise in Purgatory).
        In the eighth heaven among the stars of Gemini.

        “Dall’ ora ch’io avea guardato prima
           Io vidi mosso me per tutto l’arco
           Che fa del mezzo al fine il primo clima;
         Si ch’io vedea di là da Gade il varco
           Folle d’Ulisse. e di qua presso il lito
           Nel qual si fece Europa dolce carco;
         E più mi fora discoperto il sito
           Di questa Aiuola, ma il sol procedea
           Sotto i miei piedi un segno e più partito.”
                            _Par._ xxvii. 79-87.

                 “Since the first time that I had downward looked
                     I saw that I had moved through the whole arc
                     Which the first climate makes from midst to end;
                  So that I saw the mad track of Ulysses
                     Past Gades, and this side well nigh[454] the shore
                     Whereon became Europa a sweet burden;
                  And of this threshing-floor the site to me
                     Were more unveiled, but the sun was preceding
                     Under my feet, a sign and more removed.”

------------------------------------------------------------------------
[454] Or “nigh me:” “presso” may mean either.
------------------------------------------------------------------------


2. THE INFERNO.

Using the above table as a guide, we may now see how Dante uses the
movements of the heavenly bodies both for time and direction, and we
shall discover how long his journey takes.

Dante has spent a night in a dark forest. The moon was then full; but
we only learn this later, when Virgil reminds him of it, and he himself
mentions it to Forese, when talking in the Purgatorio. At dawn he finds
himself at the foot of a hill on which are already shining the first
rays of the morning sun—the planet which leads all aright by every
path. The sun rises: it is in Aries, consequently the moon, being full,
must be in Libra, and must have set as the sun rose, i.e. at about 6
a.m. Virgil appears, rescues the poet from three terrible beasts, and
announces that he has come to conduct him through Hell and Purgatory,
and to lead him to Beatrice, who will guide him to Paradise.

On the evening of the same day, at twilight, the poets enter the
Inferno. This great subterranean cavity, shaped like an inverted cone
(see fig. 45), is divided into nine circles, in which the different
classes of sinners are punished. In this blind world of eternal
darkness no star shines, and the sun is never once mentioned as
timegiver; when Virgil wishes to remind Dante that they must hasten, he
refers to the position of moon or stars, and the former is called “La
Donna che qui regge.”[455]

------------------------------------------------------------------------
[455] “The Lady who rules here.” _Inf._ x. 80.
------------------------------------------------------------------------

After passing through four circles, Virgil says that every star is now
sinking which was ascending when he started, indicating that it is
now six hours since they entered the Inferno, or soon after midnight.
He does not mean that all these stars are setting, but that they have
crossed the meridian, and are at some point of their descent towards
the west. Strictly speaking this does not apply to stars north of the
equator, since they take more than six hours to reach the meridian,
being above the horizon for more than twelve. Perhaps Virgil is
thinking chiefly of the constellations of the zodiac.

The poets cross the fifth circle, enter the “basso Inferno”[456] or
city of Dis, and on the edge of the precipice which borders the circle
of the Heretics they sit while Virgil explains the system of the
several circles. Then he expresses a wish to continue the journey, for
the Fishes (of the zodiac) are quivering on the horizon, and the Wain
lies to the north-west. As it is the time of the Vernal Equinox, and
the sun is in Aries, Pisces is the zodiacal sign immediately preceding
the sun, and begins to rise about four in the morning. The part of Ursa
Major called the Wain is somewhat less than 180° distant from Pisces;
hence when the latter appears on the eastern horizon the former will be
in the west (and of course always in the north). The “Caurus” of the
Latins was the wind from the north-west.

------------------------------------------------------------------------
[456] “Lower Hell.” _Inf._ viii. 75.
------------------------------------------------------------------------

They descend a cliff over loose stones which roll under the
unaccustomed weight of Dante’s living feet. Virgil tells him that
both here and elsewhere in Hell the ancient rocks were riven by an
earthquake which immediately preceded the triumphant descent of Christ
after His crucifixion. So mighty was the shock that he thought the
universe was dissolving into chaos by the force of love, as Empedocles
had said must happen periodically. At the base of the cliff they cross
the river Phlegethon, then pass through the wood of the Harpies, and
walk along the stone banks of a conduit which afterwards falls with
thunderous roar down a steep precipice. On the burning sand through
which the conduit runs, Dante sees Brunetto Latini, and tells him that
it was only yesterday that he escaped from the Forest. The monster
Geryon carries them down the precipice, and they reach the ten Pits of
Malebolge, which like so many moats surround the central Depth.

When looking down upon the astrologers in the fourth Pit, Virgil again
hastens Dante on, telling him that now Cain and the thorns—by which
he means the moon, alluding to the legend[457]—is on the boundary of
the two hemispheres, and already touching the waves below Seville.
The two hemispheres are those of the habitable earth whose centre is
Jerusalem, and the uninhabitable with Purgatory at its centre: the
moon, therefore, is just setting as seen from Jerusalem, and in the
Inferno the time is Jerusalem time. It is here that Virgil adds, “And
yesternight the moon was full:” did we not know this, the fact that
she was setting would give no clue to the time. When full, she set as
the sun rose, that was at 6 a.m.; now, therefore, she is setting after
sunrise, between six and seven in the morning;[458] and this is how
Virgil tells Dante, without mentioning the sun, that a new day has
begun.

------------------------------------------------------------------------
[457] _Cf. Par._ ii. 48-51.

[458] The retardation is not likely to be more than the average of 50
minutes, and may be less, because the moon is in Libra, and therefore
going south. This tends to diminish the interval between one moonset
and the next in the northern hemisphere, just as the days get shorter
when the sun goes south in autumn.
------------------------------------------------------------------------

The poets accordingly hasten on to the bridge above the next Pit, the
fifth, and here the demons treacherously mislead them by assuring them
that the next bridge directly on their way is broken down, but the
one to the left is standing. The anniversary of the catastrophe is
precisely determined by Malacoda, the chief demon of the band, as five
hours later than the present hour on the preceding day. There can be no
doubt that he refers to the same earthquake as Virgil described when
descending the stony cliff, and all commentators are agreed to this.
The time now, therefore, is five hours before midday, _i.e._ 7 a.m.,
since it was at midday that Dante believed Christ to have died.[459]

------------------------------------------------------------------------
[459] Some think the interval between this reference and the last
almost too short, but the words do not indicate that Malacoda spoke on
the stroke of seven! and the moon may have set at about 6.30.
------------------------------------------------------------------------

The scenes with the demons follow, the breathless escape into the next
Pit, of the Hypocrites, and the horrors of the Pit of the Thieves.

Then for a short space, when the suffering and the murk of Hell is
becoming almost intolerable, we are suddenly lifted into the upper
air by the narrative of Ulysses—into the pure air and the vast spaces
of the southern ocean, and we see once more the skies. We follow the
adventurers to the regions beyond the sun, the world where no one
lives; we see all the stars of the other pole, and the moon shines down
upon us. Too soon comes the tragic end of the story, and the waters
close over the ship; the shade of Ulysses passes on, and we are once
more in the “buio d’ inferno.”[460]

------------------------------------------------------------------------
[460] “Darkness of Hell.” _Purg._ xvi. 1.
------------------------------------------------------------------------

At the next Pit, that of the Schismatics, as Dante stands ready to weep
for pity on the bridge above it, Virgil reproaches him for delaying,
for little remains now of the time permitted for seeing the Inferno,
and already the moon is beneath their feet. This is about an hour
after midday; for if the moon were full she would be just opposite the
sun, hence under our feet when the sun is on the meridian, _i.e._ at
noon; but this is one day after Full Moon, and therefore she does not
reach the position till about an hour later.

The tenth and last Pit is traversed, and when the giant Antæus has
lifted them down into the sorrowful pit towards which all the rest
of Hell converges, the poets have nearly reached the centre of the
earth. For they have been descending continually, finding a slight
fall between each circle, and between the great divisions of different
classes of sin, three sharp steep falls—the cliff descending to the
River of blood and other circles of the violent, the precipice down
which Geryon carried them to the Malebolge of Fraud, and the Dark Pit
to the bottom of which Antæus conveyed them, where in the Frozen Lake
treachery was punished. Last of all, at the very centre and bottom of
the whole “dolorous kingdom” of Lucifer, they see its King, and Virgil
says all has been seen, and it is time to depart, for Night is rising
again.

Thus we see that the journey through the Inferno has taken exactly the
time from one sunset to another, twenty-four hours.

Now Virgil seizes the shaggy side of the fiend, while the monstrous
wings are raised, and with Dante clinging to him climbs down the side,
as far as the hip; here with difficulty and labour the master turns
round, so that his head is where his feet were, and climbs up, panting,
so that Dante thinks they are returning. But when the ascent has been
made, and both poets sit down to rest, Dante sees to his astonishment
that the frozen lake is gone, the head and wings of Lucifer are gone,
they are looking down upon him, and see only his legs which are
directed upwards! To add to Dante’s bewilderment, Virgil now says,
“Rise, for the way is long and the road is bad, and the sun has already
returned to middle-tierce,” which, as we have seen, means at the
time of the equinox 7.30 in the morning. Night was just beginning in
the dreadful place they have so recently left, but now for the first
time Virgil mentions the sun as giving them the time, and it is early
morning.

The explanation is that the point which they passed with so great an
effort is the exact centre of the world; they are now on its further
side, and above them is the other hemisphere, where all is ocean save
the island of Purgatory. Virgil explains how it was through the fall
of Lucifer from Heaven that all the land except Purgatory is in one
hemisphere, and that there is a cavity through which they may now climb
to the opposite hemisphere. When Lucifer fell, all the land which then
existed in the unknown hemisphere fled for fear of him, sinking under
the sea, and then escaping round the globe settled in the inhabited
hemisphere. It may be, he adds, that then the earth in the interior
fled away from him upwards to form land in this hemisphere (Purgatory)
and thus an empty space is left here. Up this, which is the same length
as the tunnel of the Inferno, they climb, guided through the darkness
by the sound of a little brook which has worn its winding way down
the rock. On this route there is nothing to detain them, for they are
alone in the darkness, but it presumably takes much longer to ascend
than it did to descend, for climbing without a pause it takes about
twenty-three hours (from the centre) to reach that round hole in the
rocks through which at last they once more see the stars, just before
the dawn of a new day.


3. PURGATORY.

Leaving Earth’s centre at sunset by Jerusalem time, sunrise by
Purgatory time, the poets emerge next morning by starlight when the
morning star is making all the orient smile. Henceforth Dante does not
need to be told how moon or stars are standing in the sky: he has but
to look up, and see the sun and sometimes the moon by day, the stars
and sometimes the moon by night. The Inferno was like one long dark
night, Paradise will be one brilliant day; in Purgatory the sun rises
four times and sets three times, before Dante reaches the summit, and
thence rises to Paradise with Beatrice.

“Lo bel pianeta che ad amar conforta”[461] is of course Venus: if there
were any doubt about this, the words used concerning the dawn of the
last morning on the Mountain would solve it, for there “Cytherea” is
spoken of as shining in the east on the mountain. She is in Pisces,
the sign which rises about two hours before Aries, or 4 a.m. at this
season, and as the stars are still clearly visible, it is about 5 a.m.
The poets have evidently come up from the subterranean passage facing
east, for they see Venus first, then Dante turns to his right (south)
and sees the four brilliant stars near the south pole, then turning
towards the north pole he sees that the Wain has disappeared beneath
the horizon, and close beside him he finds Cato, on whose face the
Four Stars are shining. Cato tells them that the sun, which is about
to rise, will be their guide to reach the Mountain, and as they first
go down to the shore, following his instructions, daylight begins to
appear.

------------------------------------------------------------------------
[461] “The fair planet which kindles love.”
------------------------------------------------------------------------

While they are still on the shore the sun reaches the point just below
the horizon, for he is described as just touching the western horizon
of the other hemisphere, whose zenith is above Jerusalem, and night is
just rising on the eastern horizon of that hemisphere. Where the poets
are the rose colour in the east is turning to orange, just before the
sun rises. It rises over their horizon while they are watching a light
far over the sea, which with almost incredible rapidity draws near,
becomes visible as a vessel, touches land, the spirits disembark, and
the celestial pilot “sen gì, come venne, veloce.”[462] The sun has now
driven Capricorn from the mid sky with his bright beams, that is, the
stars have become invisible in bright daylight, and fig. 46 shows that
when Aries rises over the eastern horizon Capricorn will be overhead.
But the sun is still very low, so swift was the coming of the spirits,
for Dante’s shadow is not yet visible to them: it is by his breathing
that they perceive he is a living man. It is only after the meeting
with Casella, and the dispersal of the spirits by Cato, that the sun,
still red with sunrise tints, makes Dante’s shadow fall in front of him
as the poets are walking westward towards the mountain. He is alarmed
not to see Virgil’s shadow on the ground beside it, and is told that
the body within which Virgil once had cast a shadow lies buried in a
country where it is now the time of vespers. That is, in Italy it is
three o’clock in the afternoon: hence in Purgatory, where they now are,
it is six in the morning.

------------------------------------------------------------------------
[462] “Departed, as he came, swiftly.”
------------------------------------------------------------------------

[Illustration: Fig. 46. The Signs of the Zodiac as seen at sunrise
from the Mountain of Purgatory at the autumnal equinox there (the
_vernal_ equinox in the Northern Hemisphere). _Purg._ ii. 55.

    At 6 a.m. Aries is just rising, Libra the opposite
    constellation is just setting, while Capricornus
    has just reached the meridian. The signs follow one
    another in their diurnal course over the sky in the
    direction shown by the arrows, circling parallel to
    the celestial equator.]

At the foot of the mountain they are joined by a band of spirits, and
walking very slowly with them, conversing with Manfred, so much time
passes that to Dante’s surprise, when they reach the place where the
ascent is to be made (still on the eastern side), the sun has travelled
fully fifty degrees since rising. As the sun passes over 360° in 24
hours, this indicates about 3½ hours after sunrise, or 9.30 a.m.[463]
The climb to the first ledge is slow and very arduous, for as Virgil
explains, the lower slopes are the most difficult, since the act of
climbing becomes more and more easy as the ascent is made. Resting on
a ledge, they look back and at the sun, and note how it has travelled
north, so that it now strikes their left shoulders; and after a
conversation with Belacqua Virgil begins to mount again, saying that
it is noon. The other hemisphere consequently is all in darkness, from
Ganges (“la riva”[464]) to Morocco.

------------------------------------------------------------------------
[463] If the meaning is that the sun is now 50° _above the horizon_,
this would indicate a later hour, nearing midday, for the sun does not
rise vertically in this latitude, and reaches only 58° at noon at the
time of the equinox. But the first explanation is the more probable.

[464] “The shore.”
------------------------------------------------------------------------

Other spirits have been met and spoken with, and they are still
climbing when evening comes, and Dante, thinking he is to reach the
summit of the mountain and see Beatrice that day, entreats Virgil to
hasten. “See,” he says, “how the mountain now casts a shadow.” For
the sun has travelled round to the west, and the poets, still on its
eastern side, are in deep shadow: this explains how, when they meet
Sordello, he does not recognize that Dante is a living man, as all the
spirits until now have done. But Virgil assures him that the way is
longer than he knows: before they reach the summit, the sun, now hidden
behind the mountain and not causing Dante to cast any shadow, will
return again to the east.

[Illustration: Fig. 47. Northern slope of the Mountain of Purgatory,
up which Dante climbed. Being in the southern hemisphere, this was the
sunny side, and he followed the sun’s course, from east through north
to west.]

Immediately after this, they meet with Sordello, who tells them that
it is impossible to climb even one step on the mountain after sunset,
and leads them to a flowery valley, in which to rest for the night.
The spirits in the valley sing the evening hymn while the sun sets;
and it begins to grow dark while Dante is talking with judge Nino,
explaining whence he came that morning. As soon as the stars become
visible, his eyes seek the southern pole, and fix themselves on three
brilliant stars which have taken the place of that constellation of
four which he saw some fourteen hours before. The latter have travelled
to the south-west, and are hidden behind the mountain, and the new
constellation is above the pole towards the east.

Night has risen two steps and part of a third in this place when
Dante falls asleep, and the most natural meaning of this is that it
is somewhat more than two hours after sunset, or after 8 o’clock, in
Purgatory. The moon has not yet risen, since she is like a clock which
loses on an average 50 minutes every day.

Since the first morning in the Forest, when she was exactly 12
hours behind the sun and set at six o’clock, three whole days have
elapsed,[465] and if she has lost 3 times 50 minutes, or 2½ hours, she
will rise 14½ hours after the sun rises, that is 2½ hours after sunset,
or at about 8.30. As the retardation varies much, let us say simply
that she rises to-night between eight and nine o’clock. She has also
moved among the stars, about 13 degrees each day, and as 3 × 13 = 39,
and there are 30° in a zodiacal sign, she has passed out of Libra and
is in Scorpio. Libra begins to rise at 6 p.m., and Scorpio at a little
before 8, therefore part of Scorpio is now above the horizon.[466]
This, then, is the meaning of the first two stanzas of Canto ix.: the
mistress of Tithonus is the aurora before moonrise (the solar aurora
being his wedded wife, according to classical mythology), and this
pale aurora is showing white in her balcony of the eastern sky, while
on her forehead shine the stars of Scorpio, the cold creature with the
stinging tail.

------------------------------------------------------------------------
[465] See table on p. 361.

[466] “We must not assume, as some commentators have done, that the
signs rise at equal intervals of two hours, although each circles the
star sphere in 24 hours. See fig. 46, where the dotted line shows how
_e.g._ Cancer, circling parallel with the celestial equator, will rise
at a point considerably north of east, and having had to traverse more
than 90 degrees since Aries rose due east, will not rise until about 7
hours later, _i.e._ 1 p.m. Conversely Scorpio, following Libra, will
rise south of east, and a little _less_ than 2 hours later. The moon’s
retardation, therefore, is less in this part of the zodiac than it
would otherwise be, and the hour is probably nearer eight than nine.”
------------------------------------------------------------------------

This curious passage has been otherwise interpreted by some
commentators, and Scartazzini calls it “oscuro al superlativo,”[467] a
riddle which still waits its Œdipus. According to him, “Titone” should
be read “Titan,” the sun-god, and his mistress is Tethys the ocean,
which is now shining not under his rays (“fuor delle braccia del suo
dolce amico”[468]) but under the rays of the rising moon. This seems
far-fetched, and the reading doubtful. In any case, it would indicate
the same hour and the same phenomenon (moonrise).

------------------------------------------------------------------------
[467] “Superlatively obscure.”

[468] “Out of the arms of her lover.”
------------------------------------------------------------------------

Others think that the solar aurora is intended, and explain the “freddo
animale”[469] as Pisces, and the “steps” as the watches of the night.
But why a terrible tail should be ascribed to a fish is not clear, nor
is it easy to see how the third step with which Night ascends could
be the hour of dawn. Night, which circles opposite to the sun, surely
reaches the culminating point and begins to descend at midnight, just
as midday is “il colmo del dì.”[470] Moreover, the third watch would
bring us at latest to a little before 3 a.m. To make the “steps” signs
of the zodiac is no better; for if Libra, Scorpio, and Sagittarius have
risen, it is midnight; what then can be shining in the east? and on
whose forehead are the stars of Scorpio glittering?

On the other hand, all accords well if we accept the first
interpretation—the light of the moon just about to rise whitening
the eastern sky, some brilliant stars of Scorpio shining there, and
Dante falling asleep at the third hour of the night, wearied after his
sleepless nights, and the hardest day’s climb that he will have. We
need not grudge him his long sleep of nearly twelve hours, as those do
who take this passage to indicate midnight or early morning.[471]

------------------------------------------------------------------------
[469] “Cold creature.”

[470] “The climax of the day.”

[471] See Moore, _Studies in Dante_ iii. pp. 75-84, for a detailed
discussion of this passage. Several commentators have held that lines 1
to 6 describe the dawn of day _elsewhere_; and it is true that it would
be nearly 6 a.m. and Pisces would be on the horizon in Italy when the
hour was nearly 9 p.m. in Purgatory.
------------------------------------------------------------------------

When Dante wakes the sun has already been up for more than two hours,
but a dream which had come to him in the early dawn, at the time when
the swallow begins to twitter, has had its counterpart in the truth,
that the lady Lucia came at that time and carried him up the mountain
side, leaving him outside the Gate of Purgatory when the day was bright.

When this Gate has been passed through, a narrow chasm between the
rocks has to be climbed, and the passage is so difficult that it is at
least an hour before the poets emerge on the open space of the First
Cornice. For the waning moon has already set, and as she has lost
another half hour or so during the night, the time of her setting this
morning was about 9 a.m.

When Dante next notices the position of the sun, which he is too intent
to do for some time, they have travelled some distance along the First
Cornice, with its outer edge on their right, and the sixth handmaid
is returning from the service of the day, that is, the sixth hour is
ended: it is midday, and they have spent nearly three hours here,
looking at the rock sculptures and conversing with the spirits.

The ascent to the Second Cornice is made with marvellously little
fatigue, as Virgil had promised. There they at first find no one to
direct them, so Virgil looks at the sun, and turns westward towards
it, taking it as their guide, and they walk for about a mile before
encountering any spirits in this circle.

The stairway to the next Cornice is reached at the time of vespers,
that is, 3 p.m.; and Dante describes the position of the sun by saying
that the portion of sky which it still had to traverse before evening
was equal to the portion which is brought into view between the
beginning of the day and the end of the third hour, that is, it was
three hours before sunset; and he compares this ceaseless motion of the
sky, which according to the Ptolemaic system caused the motion of the
sun, to an ever-playing child. We need not particularly enquire whether
he is thinking of the heaven of the sun, or the Primum Mobile: it may
be either, but is most likely simply the diurnal movement in general,
made strikingly evident by the sun. The sun’s rays now strike their
faces, for they have so far circled the mountain that they are walking
towards the west; “Vespero là”[472] means in Purgatory, and “qui”[473]
is Italy, where it is midnight now.

------------------------------------------------------------------------
[472] “Vespers there.”

[473] “Here.”
------------------------------------------------------------------------

The sun is low when they reach the third Cornice, and when they emerge
from the dense cloudy fog which here envelopes the spirits, Dante
gradually sees the ball of the sun as when mists clear away, and he
sees that it is just about to set. In fact the low shores at the foot
of the mountain are already in shadow. Virgil urges that they make the
ascent to the next Circle before darkness comes, and, as each ascent is
easier than the last, they are able just to reach the summit before the
sun is quite gone. Here Dante sees the stars begin to appear, while he
is wondering at the strange law which robs him of power to proceed (as
Sordello had warned them) after the sun has set.

They employ this time of forced inaction by talking of the sins which
are punished in the several Circles, until all Dante’s questions are
answered, and he is beginning to fall asleep. It is at this moment that
he first mentions the moon: she is glowing, shaped like a bucket in her
present phase, and the stars are paled by her light. She is “belated
almost till midnight,” if the epithet “tarda” belongs to her; if it
applies to “mezza notte,” then it is almost late midnight when she is
seen paling the stars. She ought to have risen about ten o’clock, but
Dante does not speak of her rising, so this may mean simply that it was
moonlight and starlight at the time of which he is about to speak, viz.
nearly the late hour of midnight; or else that since he is now on the
northern slope of the mountain, and the moon is in a southern sign, she
did not become visible to him till towards midnight. In any case, the
“quasi” shows that he is only giving us a rough idea of the time.

But in what sign was she? Her position in the zodiac is described in a
peculiarly round-about fashion. Dante says that her course _against the
sky_, that is, her monthly motion which is contrary to the diurnal,
had taken her to that part of her track in which the sun is when from
Rome he is seen to set between Sardinia and Corsica. The straits
between these islands lie west and a little south of Rome, therefore
the sun sets in that direction when he is going south after passing the
autumnal equinox in Libra, and this is just what the moon is doing now.
(The sun passes the same point again when coming north, before entering
Aries at the spring equinox, but Dante has either forgotten this, or
considers it obvious that the first position is meant here).

This is probably all that he means to convey, and if we ask for more
exact information, it is almost impossible to tell what degree or even
what sign in the zodiac he intends us to understand; for as the straits
are nearly two hundred miles from Rome they are quite invisible thence,
and we do not know what he thought was their precise direction. The
mediæval commentator Benvenuto da Imola says that the position intended
is in Scorpio; the moderns usually say Sagittarius, but without
explaining how they draw this conclusion. Benvenuto’s is probably
simply the position which he thought the moon ought to have in order to
agree with what Dante says about her, just as he states that Venus was
in Pisces in March 1300, although this was not the case at all, as we
shall presently see.

A calculation based on the difference in latitude between Rome and the
Straits shows that they are only about 9° south of west, and that the
sun, when setting in this direction is about 6° south of the equator:
this is the case 15 days after the equinox, which in the beginning
of the fourteenth century fell on September 14. Therefore the date
at which the sun was seen from Rome setting in the direction between
Sardinia and Corsica was the 29th of September, and its position in the
zodiac was then the middle of the sign Libra. (Owing to precession,
it would be in the _constellation_ Virgo, but we have seen that Dante
ignores precession in these references.)

But the moon ought now, on this second night in Purgatory, to
have reached at least the last degrees of Scorpio, since on the
previous night she rose when the first part was already above the
horizon. Dante has therefore made a flagrant mistake with his moon,
running her back into Libra again, and falsifying all his previous
descriptions—_if_ he knew as much about geography as we do now. But it
is only necessary to glance at the map of Henry of Mainz to see that
such a supposition would be grotesque. The portolan maps did indeed
show the relative positions of Rome, Sardinia, and Corsica, with
remarkable accuracy;[474] but as we have already said, it is not in
the least likely that Dante had ever seen one of these sailing charts.
It was on the classics, and especially on Orosius, that he relied
for his geography,[475] and the suggestion of Dr. Moore seems most
plausible, that he was here thinking of the Spaniard’s description of
Sardinia:—“Habet _ab oriente et borea_ Tyrrenicum mare quod spectat ad
portum urbis Romae.”[476] This implies that Sardinia lay south-west of
Rome, in a direction such as the sun might have had when setting in
November, in Scorpio or Sagittarius.

------------------------------------------------------------------------
[474] See for instance the “Carte Pisane,“ and the Central
Mediterranean map of Vesconte, dating from about 1300 and 1311
respectively, in Beazley’s _Dawn of Geography_, iii. Latitudes and
longitudes are not given, but from certain centres lines radiate to all
points of the compass, like great spiders’ webs.

[475] _De Mon._ II. iii. 87-90. etc.

[476] “It is bounded _on the east and north_ by the Tyrrhenian sea,
which lies towards the port of Rome,” Moore, _Studies in Dante_ iii. p.
72.
------------------------------------------------------------------------

Or possibly, when the poet was in Rome in 1301, he may have been
watching a sunset in the second week in November, and may have been
told, among other pieces of misinformation which are so readily given
to visitors to great cities, that he was looking towards the straits
which separate Sardinia from Corsica. We can imagine his replying, or
thinking: “Then the sun sets behind them when he has nearly finished
his course in Scorpio, and is about to yoke his steeds under another
star!”[477]

------------------------------------------------------------------------
[477] _Purg._ xxxii. 56, 57.
------------------------------------------------------------------------

It is while the moon is shining on this Cornice that the spirits who
purge their sins on it appear, rushing past in haste. Then at last
Dante sleeps, and dreams again in the cold moonlit dawn when Aquarius
and Pisces are on the horizon (see p. 290).

The mountain is full of daylight when Virgil wakes him, and the
newly-risen sun shines behind them as they continue their journey, for
they had reached the north point of the circle, and are walking now
due west. They mount almost immediately to the Fifth Cornice, where
presently they are startled by a violent trembling of the mountain
followed by a mighty shout of “Gloria in excelsis” from all the
spirits. Statius joins them, and from him they learn that this was
no earthquake, for since passing the gate of Purgatory they are in
a region too lofty for such disturbances to be felt, or for rain or
snow or dew to fall; the mountain trembles, and the shout of praise
follows, when a soul rises, purified and ready to ascend to Paradise.
With Statius they climb to the Sixth Cornice, and then, looking round,
they see that the fifth handmaid of the sun’s chariot is directing
its upward course, that is, it is the fifth hour, or between 10 and 11
a.m. As usual, they walk on with the outer edge of the circle on their
right. It is here that we are reminded, as once in the Inferno, that
only a certain time is allowed, for while Dante is looking eagerly at
the first mysterious tree Virgil gently urges him onward:—

    “Lo più che padre mi dicea, Figliuole,
     Vienne oramai, chè il tempo che c’ è imposto
     Più utilmente compartir si vuole.”[478]

------------------------------------------------------------------------
[478]
    “My more than father said unto me, Son,
     Come now, because the time that is ordained us
     More usefully should be apportioned out.”
     _Purg._ xxiii. 4-6. (_Longfellow_).
------------------------------------------------------------------------

It is here also that Dante informs his old friend Forese Donati and
other spirits, who are all astonished at the sight of his shadow, that
he is a living man who was rescued by Virgil some days ago, when the
sister of the sun was round (referring of course to the full moon in
the forest), and he points to the sun. Now a curious question arises:
Dante was in sunshine in the early morning; he is in sunshine now, and
has been walking all morning in the same direction in which the sun was
moving; how is it then that Statius did not notice his shadow, but had
to be told that he was not a spirit?[479] If the Mountain had been a
small hill, it would have been quite easy to walk so large a part of
a circle round it, in a short time, that the poets would have been in
shadow until the sun caught them up again when they lingered talking
on the Sixth Cornice; but the Mountain was so large that a whole
day’s walking only brought them a quarter of the way round, _i.e._
from the east side to the north, and it was evidently a distance of
many miles.[480] It is difficult to believe that Dante has forgotten,
because he is so careful throughout to mention the surprise of the
spirits except when his shadow could not be seen for one reason or
another. It is true that in the latitude of Purgatory (32° south, as
that of Jerusalem is 32° north), the sun rises rather steeply, which
makes it easier to get into the shade in the early morning while
circling a mountain.[481] On the other hand a simpler solution offers
itself in the text. Statius approaches Dante and Virgil from behind,
and they only stop and turn their faces to him for a few moments while
Virgil returns his greeting, then walk on quickly while Statius makes
his surprised reply: “What! if you are spirits....” If he has not yet
quite overtaken them he cannot see Dante’s shadow, which Dante himself
is screening from view as it falls in front of him, the morning sun
being still at his back, and Virgil explains at once that his companion
is a living man.

------------------------------------------------------------------------
[479] _Purg._ xxi. 20-27.

[480] _Purg._ xiii. 22-23.

[481] On an Astronomical Point in Dante’s _Purgatorio_, by P. H.
Cowell, F.R.A.S., _The Observatory_, December 1906.
------------------------------------------------------------------------

In spite of their haste, the three poets remain about four hours in
this sixth Cornice; and when they reach the ascent to the next it
was indeed time to climb without any delay, for the sun had left the
meridian to the sign which follows Aries, viz. Taurus, and Night, “che
opposita a lui cerchia,”[482] had left the meridian of the opposite
hemisphere to Scorpio. Aries at the time of the equinox begins to
cross the meridian at midday, Taurus at two o’clock, and Gemini at
four[483]: therefore it is now between two and four in the afternoon.
The three poets hasten therefore (Statius still accompanying Virgil
and Dante), like men who pause for nothing on their way, whatever the
road be like; and a question Dante is longing to ask with regard to
the form of purgation last seen is put and answered as they follow one
another up the narrow stair; as soon as they reach the top, they turn
to the right, as usual, without hesitation or delay. As Dante walks
cautiously between the outer edge of this Cornice and the fire which
bursts forth from the inner wall of rock, all the blue of the western
sky is already changing into ash-white, and he has come so far round
the Mountain that the evening rays strike his right shoulder. With
one of the many touches which show Dante’s close observation and his
vivid realization of the scene he is describing, he says here that his
shadow falling on the flame makes it appear a deeper red, and this is
observed by the spirits. When they reach the spot where, on the further
side of the flames, the chanting Angel guides them across to the last
ascent, the sun is very near to its setting. Its burning noonday beams
are shining on the waves of Ganges, its first morning beams quiver over
Jerusalem, and Spain lying under Libra is wrapped in midnight gloom;
hence it is beginning to set at sea-level in Purgatory. High on the
Mountain it still shines, but when the poets have crossed the flames,
the voice of the Angel persuades them to hasten their steps before the
darkness comes. The stair mounts through the rock on the west side of
the Mountain so that the low sun casts Dante’s shadow in front of him
as he climbs. And he has only climbed a few steps when they are all
aware that the sun has completely set because the shadow disappears.
Before the colour has all faded from the west, and the whole vast range
of the horizon seen from this height has become one uniform tint, each
of the three makes a bed of one step, and between the high and narrow
enclosing rocky walls Dante sees the stars come out, much brighter and
much larger than he has ever seen them before. No moonlight dims them,
for moonrise will be late to-night, long after Dante has fallen asleep.

------------------------------------------------------------------------
[482] “That circles opposite to him.” _Purg._ ii. 4.

[483] The signs follow one another _on the meridian_ at intervals of
exactly 2 hrs.
------------------------------------------------------------------------

Once again, for the third and last time, he has a prophetic dream in
the early dawn; and if we compare these three parallel passages, we
find that each begins with the same words “Nell’ ora.”[484] The first
time the ideas connected with the time are wholly sorrowful, for it is
said to be the hour when the swallow begins to twitter, perchance in
memory of her former woes—alluding to the tragic tale of Procne and
Philomel. The second is a depressing time, for it is the cold hour
when, the day’s heat being all spent, the chilled earth cannot overcome
the influence of the cold planets such as the moon or Saturn, but there
is a thought of hope in the stars of the Greater Fortune seen rising
in the east, in a sky which is now scarcely dark to them. The third is
all joy, for it is the hour when Cytherea (the planet Venus), burning
ever in the fire of love, shines first upon the mountain. Dante’s sleep
flees from him as the shades of darkness flee on all sides, chased by
the brightness before sunrise; and when Virgil tells him that to-day he
shall reach the goal of his desires, he speeds up the remaining steps
of the stair, almost as if on wings.

------------------------------------------------------------------------
[484] “At the hour.”
------------------------------------------------------------------------

The poets arrived on the shores of Purgatory, as we saw, facing east,
and now that they have attained the summit of the mountain, coming up
the western slope, they again face east, and the just risen sun shines
in their faces. Dante walks towards it: a breeze fans his forehead and
causes all the trees to bend in the direction of the shadow thrown at
sunrise by the Mountain (_i.e._ westwards), and the murmur of this
gentle wind in the branches forms a bass to the treble of the singing
birds who are greeting the morning hours. For a few steps the stream of
Lethe stays his steps in this direction, but he soon reaches a bend,
and once more “a levante mi rendei.”[485] The symbolical procession
which accompanies Beatrice comes towards him from the east, and after
he has crossed the river Lethe and joined the procession beside the Car
in which Beatrice is throned, all turn to the sun, which by this time
must have travelled some distance towards the north. After the vision
of the disasters which befell the holy Car, and after Beatrice has
spoken with Dante again, they reach the fountain whence Eunoe flows,
and now the sun is on the meridian and it is noon, though (as Dante
reminds us) different places have different meridians, so that it is
not noon everywhere else. He is bathed in the holy waters, and thus,
all having been accomplished for which he has visited these regions, he
is “puro e disposto a salire alle stelle.”[486]

------------------------------------------------------------------------
[485] “I turned to the east.”

[486] “Pure and ready to rise to the stars.” _Purg._ last line.

Hell was entered at twilight, Purgatory at dawn, the ascent to Paradise
is made at noon, “il colmo del dì.”[487] The time spent in Purgatory is
three days and the morning of a fourth, which is the seventh from the
beginning of the vision.

[487] “The climax of the day.”
------------------------------------------------------------------------


4. PARADISE.

That the time of ascent to the spheres was noon is again stated in
the opening Canto of the _Paradiso_, where Dante says that the sun
had brought morning there (Purgatory) and evening here (the inhabited
hemisphere), and that now the whole of that hemisphere was bright while
the whole of this was dark.[488] The sun is therefore now due north.
While Beatrice stood beside the waters of Eunoe, after walking towards
the sun, it had moved to her left, so she now turns in that direction
to gaze upon it.[489] She, like Virgil, takes as her guide that sun
which Dante has said is the fittest symbol of God, and it is through
the power of this heavenly light that he is raised from earth. Compare

[488] It has been suggested to read the line _Par._ i. 44. “Tal foce; e
quasi tutto là era bianco,” transferring the “quasi” (almost) so that
the meaning should be “almost was wholly white that hemisphere,” and
to interpret that it is now morning of the day following the events
in the last Canto of the _Purgatorio_. But if so, Dante would have
spent a whole night in the Earthly Paradise without mentioning it, or
explaining this long delay after he had become “pure and ready to rise
to the stars.” (For the meaning of “foce,” the “passage,” see later, p.
400).

------------------------------------------------------------------------
[489] _Par._ i. 46, 47.
       “Amor che il ciel governi
    ... _col tuo lume_ mi levasti.”[490]

[490]
    “Love that rules the heavens,
    _with thy light_ Thou didst raise me.”
                         _Par._ i. 74, 75.
------------------------------------------------------------------------

He is not conscious of any effort, or even movement, but is astonished
by a great light and strange music, and learns that he is in the sphere
of fire and listening to the harmony of the spheres. His soul, freed
from all that bound it to earth, is soaring towards its natural goal,
as fire mounts up and rivers run down.

The upward gaze to the sun or to the skies, and its power to raise
them, is again described in _Par._ i. 142: Beatrice “rivolse inver lo
cielo il viso,”[491] and in ii. 22, “Beatrice in suso ed io in lei
guardava.”[492] Thus they rise to the First Heaven, of the moon. In
answer to an eager question of Dante’s about the markings of the moon,
Beatrice is led to discourse on the spheres and their movers. Spirits
appear, and Dante learns that although all the redeemed dwell in the
Empyrean, those of different degrees of blessedness will manifest
themselves to him in each sphere. After explaining this and other
things, Beatrice once more

------------------------------------------------------------------------
[491] “Turned her eyes again towards heaven.”

[492] “Beatrice gazed upwards, and I at her.”

                “si rivolse tutta disiante
    A quelle parte ove il mondo è più vivo,”[493]

[493]
              “Turned again with yearning
    to that part where the world is most living.”
                          _Par._ v. 86, 87.
------------------------------------------------------------------------

and swift as an arrow that strikes its mark before the cord has ceased
to quiver, they ascend to the Second Heaven, of Mercury. To understand
the above lines we must remember that the sun, as Dante told us in the
introductory Canto,[494] is at the equinox, or near it, and therefore
on the equator; also that the equator of a sphere, where motion is
quickest, is its most living part.[495] Beatrice is therefore looking
again at the sun. Some understand “quella parte”[496] to refer directly
to the sun, “quegli ch’ è padre d’ogni mortal vita,”[497] some to the
equinoctial point;[498] others think that the east is meant; others the
Empyrean, in which is the true life of all the Universe.

------------------------------------------------------------------------
[494] _Inf._ i. 38-40.

[495] _Conv._ II. iv. 52-62.

[496] “That part.”

[497] “He who is father of all mortal life.” _Par._ xxii. 116; see also
_De Mon._ I. ix. 6, 7.

[498] See _Par._ x. 7-21.
------------------------------------------------------------------------

Equally swiftly and unconsciously, Dante ascends to the successive
heavens of Venus, the sun, Mars, Jupiter, and Saturn, finding himself
always in the planet which occupies each sphere. Mounting the
mysterious golden ladder which is set up in Saturn, with a rapidity
inconceivable on earth, the poet finds himself in the Heaven of Stars,
in the constellation of Gemini. Now that he is so near the final
blessedness his eyes are clear and keen, and that his heart may be
filled with joy Beatrice bids him look down and see how much of the
universe is already beneath his feet. There lie the seven spheres, and
there is the little globe of Earth, so small that, like Scipio, he
smiles at its paltry appearance; there is the moon, showing him the
face turned away from Earth, which has no dark markings: there is the
sun, at which for once he is able to gaze; and near it circle Mercury
and Venus; the temperate Jupiter moves between his father Saturn and
his son Mars; with a new power of vision Dante can grasp all their
sizes and distances and the various speeds of their movements; and
the poor little disc of the earth, small and round as a threshing
floor,[499] about which we quarrel so fiercely, is all visible to him
at a glance, its highest hills and its lowest river-valleys running
down to the sea. He turns away his eyes to look into the beautiful eyes
of his guide. She is standing, erect, intent, watching eagerly for that
glorious Procession, whose coming is making a growing brightness in the
sky.

[499] Longfellow says:—“Looking down from the terrace of Monte Cassino
upon the circular threshing-floor of stone in a farm lying below, I
first felt the aptness of Dante’s phrase. This very scene may have
suggested it to him.”

      “La donna mia si stava eretta
    Ed attenta, rivolta inver la plaga
    Sotto la quale il sol mostra men fretta.”[500]

------------------------------------------------------------------------
[500]
       “So my lady stood, erect
    and intent, turned towards that place
    under which the sun shows least haste.”
                 _Par._ xxiii. 10-12.
------------------------------------------------------------------------

No other intimation is given as to the direction from which the
Procession comes. The sun’s daily motion appears slowest on the
meridian, as Dante remarked in _Purg._ xxxiii. 103, 104, because he
is scarcely changing his position with regard to the horizon; or in
the south (where we in this hemisphere see him when on the meridian);
he shows least haste to leave us in the long summer days, near the
solstice. If the Procession descends from the heaven of heavens to show
itself here symbolically to Dante, as we know that the spirits in other
heavens did,[501] then Beatrice was gazing upwards, and the meridian
may be meant, particularly that part of it which passes directly
overhead. If the Procession came from the east, like the Procession in
Eden,[502] the summer solstice in Cancer is meant, which lies east of
Gemini. It is difficult to see any special meaning in its coming from
the south, for although some commentators say that this suggests the
consummate glory of the midday sun, the same idea is conveyed by the
meridian. A constellation like Cancer perhaps corresponds better than a
circle like the meridian with the expression “plaga,”[503] and the idea
of the east makes more perfect the beautiful simile which the poet has
just drawn between the little bird on the spray beside its nest waiting
for the sun to rise, and Beatrice watching for the advent of Him who is
likened to a sun among the starry company of His saints.[504]

------------------------------------------------------------------------
[501] See _Par._ iv. 34-39.

[502] _Purg._ xxix. 12 and 34.

[503] “Region.”

[504] _Par._ xxiii. 29, 30.

------------------------------------------------------------------------

[Illustration: Fig. 48. Dante’s first view of Earth from the Stars.
_Par._ xxii. (see p. 397).]

When this glorious company has at length vanished, she bids him look
down once more, this time that he may realise how he has been revolving
with the spheres, the little earth lying immoveable at his feet. He
looks down, and notes what parts of Earth are lighted by the sun, and
what parts are wrapped in darkness, for now he is able to see what
he had often imagined, the shadow of night sweeping westward over
the globe. The Atlantic Ocean, where Ulysses sailed beyond Gades, is
all in daylight, and so is the Mediterranean, but the sun is setting
over Jerusalem, for he says that its position prevents him from
seeing beyond the coast whence Europa was carried (_i.e._ Phœnicia or
Palestine). It must therefore be midday at Gades, and the sun is on
the meridian there; it is “a sign and more,” or something between 30°
and 60°, advanced to the west beyond the meridian over which Dante
stands.

He does not define his own position more exactly than this, but we may
conjecture that he was 45° (a sign and a half) east of the sun, since
this would be the meridian of Rome, and there would be a peculiar
fitness in such a position at such a moment, when he has just received
a message of warning and prophecy from St. Peter to bear to this
city.[505]

------------------------------------------------------------------------
[505] _Par._ xxvii. 64-66.
------------------------------------------------------------------------

[Illustration: Fig. 49. The view six hours later. _Par._ xxvii.]

Fig. 49 shows these positions of Dante and the sun, and the consequent
limits of his vision. Jerusalem is “near,” in comparison with the much
more distant sunlit space of ocean in the opposite direction. We place
the sun in the middle of Aries, because we shall see presently (when
discussing the date) that this is its most probable position, and
Dante in the first degree of Gemini because this is 45° east of the
sun, and also because the fact that he is above Earth’s “first climate”
suggests that he is in the beginning of this sign. For the northern
limit of the first climate was 20½°, according to Alfraganus, and the
ecliptic in the sign of Gemini rises gradually from 20° north of the
equator to 23½° at its end, where it adjoins Cancer.

Since the time when he looked down before, he sees that he has revolved
over an arc equal to half the climate, that is 90°, for the climates
only extended over the habitable earth, which was 180° in longitude.
His former position, then, must have been 90° further east, halfway
between Jerusalem and Ganges; and it was then noon at Jerusalem, while
all the ocean east of Ganges lay in the black darkness of night. Fig.
48 shows this position.

In this interpretation of a difficult passage, the meaning given to
the first lines seems a little forced; but if we take them in the more
natural sense that Dante had moved from above the centre to the end
of the climate, that is, from the meridian of Jerusalem to Gades, we
are met by a difficulty in the following lines. For to say that he is
standing over Gades, and in the same breath that the sun is more than
30° further to the west, means that it is setting more than 30° west
of Jerusalem: he cannot therefore possibly see Jerusalem, nor is it
“near” him. It does not help us to take “presso” in its alternative
meaning, and say that he could see “nearly as far as” Jerusalem, for
however little more than 30° “a sign and more” may mean, it brings the
“terminator” (as astronomers call the dividing line between light and
darkness on a planet) a long way from Jerusalem and much nearer Italy,
according to Dante’s reckoning of distances in the Mediterranean. This
is shown on fig. 50, where the data are made as favourable as possible,
by putting the sun at the very end of Aries.

On the whole, it is easier to accept a round-about expression in
the first lines than an inaccurate one later. The former is quite
characteristic of Dante, and we have already met some like it in
the _Divina Commedia_ in descriptions of the positions of heavenly
bodies.[506]

------------------------------------------------------------------------
[506] Compare _Purg._ xv. 1-5, where the course the sun still has to
run between vespers and sunset is described as equal to the space
between the third hour and sunrise.
------------------------------------------------------------------------

Looking back to the earlier position, as described in Canto xxii., we
find no light thrown on the question; for here he does not mention any
particular place as visible, nor say where the terminator lay. His
words are:—

    “L’aiuola che ci fa tanto feroci,
       Volgendom’ io con gli eterni Gemelli,
       Tutta m’apparve dai colli alle foci.”[507]

------------------------------------------------------------------------
[507]
    “The threshing-floor that maketh us so proud,
        To me revolving with the eternal Twins,
        Was all apparent made from hill to harbour.”
                           _Par._ xxii. 151-3. (_Longfellow_).
------------------------------------------------------------------------

This seems to express simply a bird’s eye view of Earth, as it lay
stretched out like a map below the observer.

It is, however, often taken to mean that the whole habitable earth was
visible. This could never be unless the sun, as well as Dante, was over
the meridian of Jerusalem, which is obviously impossible while one is
in Aries and the other in Gemini; and as he refers back to the first
passage from the second he cannot have forgotten this.[508]

------------------------------------------------------------------------
[508] Della Valle boldly assumes that they _were_ over the same
meridian, by a poetical licence, although at the same time the sun was
in a different sign. Dante only mentions the latter fact, he thinks, in
order to show that he was a few degrees north of the sun (Gemini being
more northerly than Aries); therefore he could see over the edge, as
it were, of the sun-lighted hemisphere of Earth. This is desperately
subtle.
------------------------------------------------------------------------

It is, however, the only way in which the passages can be reconciled
with his further assumption, shared by some other commentators, that
Dante, in his flight through the spheres, simply ascended without any
movement in longitude except that he was carried round by the daily
revolution of the spheres. All the planets, therefore, were ranged one
above the other, in the sign of Gemini, and it was always noon on the
earth below his feet, since that was the hour at which he ascended from
the Earthly Paradise, and his movement was the same as the sun’s. (Here
Della Valle is inconsistent, however, for he maintains that the ascent
was made in the early morning.) But this is a very artificial conceit,
and not indicated by Dante. He implies that Beatrice, in leading him
to each sphere, chose the part of it which he was to enter (see _Par._
xxvii. 102), and he tells us that Saturn was in Leo, Venus in Pisces,
and the sun in Aries.

[Illustration: Fig. 50. An impossible interpretation of _Par._ xxvii.]

A book which aims at explaining Dante’s _Paradiso_ to young people[509]
suggests an original way of reconciling the two passages, for the
author gravely asserts that the sun was at first below Dante’s feet in
Gemini, but that by the time he looked down again it had moved a good
distance onward, and was then in the sign of Taurus! According to this,
a whole month must have elapsed, and time had gone backwards, from May
to April!

------------------------------------------------------------------------
[509] _Il Paradiso di Dante dichiarato ai giovani_, by Angelo de
Gubernatis.
------------------------------------------------------------------------

A suggestion much more worthy of attention is that of Professor
Rizzacasa d’Orsogna, who thinks the key is to be found in the line,
“Volgendom’ io con gli eterni Gemelli.” This, he suggests, is in
anticipation of the second passage, for although Dante could not see
the whole habitable earth at any one time, his change of position, as
he revolved with the Twins, enabled him to do so in the course of time
which elapsed between his two views. A comparison of figures 48 and 49
will make this clear.

One more suggestion may perhaps be made, though it is rather a
hazardous one. “Dai colli alle foci”[510] may mean from the Apennine
Hills to the mouths of Ganges. This would be decisive for the
correctness of the explanation illustrated by our diagram. (See fig.
48).

------------------------------------------------------------------------
[510] “From the hills to the river-mouths.”
------------------------------------------------------------------------

In any case, the points which Dante specially wishes us to understand
are clear and simple: at the first glance he was struck by the
insignificance of the Earth; at the second, he became conscious that
he was moving with the spheres, having passed over 90° of arc, or a
quarter of the diurnal revolution, and he saw that it was now sunset at
Jerusalem.

He next ascends to the Primum Mobile, though he cannot tell us to which
part of it Beatrice chose to lead him, since it is perfectly uniform
throughout. Beatrice explains that this most swift and living sphere,
although it contains no star by which its motion is made visible,
causes the (diurnal) motion of all the lower spheres; and thus it is
like a flower-pot in which are hidden the roots of Time, while in
the others we see the leaves. Here he sees the nine hierarchies of
angels who direct the nine moving spheres; and finally he soars to the
Empyrean, where Beatrice returns to her seat among the blessed spirits
who form the Celestial Rose, and St. Bernard encourages him to lift his
eyes to “L’Amor che move il sole e l’ altre stelle.”[511] This is the
end and consummation of the Vision.

------------------------------------------------------------------------
[511] “Love which moves the sun and the other stars.” _Par._ last line.
------------------------------------------------------------------------

The reader will have observed that although there are several
indications of direction in Dante’s journey through Paradise, all
referring to the heavenly bodies, there are no time references after he
has left Earth and entered the regions of eternity, except the passage
discussed above, which indicates a period of six hours spent in the
eighth heaven, since 90° of the diurnal revolution correspond with six
hours of time. But it tells us also that at the close of this period
the sun was setting over Jerusalem: consequently another morning was
dawning in Purgatory. Eighteen hours have passed, therefore, since
Dante left the Earthly Paradise at noon; and he rises to the Primum
Mobile and thence to the Empyrean on the eighth day of his Vision.

The whole Vision, therefore, occupied an octave, or eight days.


5. POSITIONS OF SUN, MOON, AND PLANETS AMONG THE STARS DURING DANTE’S
VISION.

The allusions to sun, moon, and stars in the _Divine Comedy_, when
thus brought together, are seen to follow one another according to a
regular scheme, and they form a very good guide by which to time Dante
on his journey. There is a little inaccuracy in one passage about the
stars, and the moon is ambiguous once, but quite explicable. Taking
the allusions in a simple popular sense, as he seems to intend us to
do, assuming that the signs and the constellations of the zodiac are
identical, and that the moon, which at first is opposite the sun,
traverses about 13° in the zodiac daily, and loses about an hour of
time more or less, there is very little difficulty in following him. It
is quite enough to know that the sun is somewhere in Aries throughout,
and that the moon is therefore in Libra at the beginning.

[Illustration: Fig. 51. The rising sun at the Spring Equinox.]

But if we wish to know a little more accurately the positions of sun
and moon among the stars, we must carefully compare the passages
bearing on this question. Commentators differ so much that while some
think the sun’s annual motion is ignored, and it is assumed to be at
the equinox all the time, others maintain that it was at the equinox
on the first day and moved on through Aries at the rate of about one
degree a day (as it should do, since there are 365 days in a year and
360° in the circumference of the sphere);[512] while others again say
that it was merely somewhere in Aries from the beginning.

------------------------------------------------------------------------
[512] Alfraganus, as we saw, gives the daily movement of the sun
eastward in the zodiac as about 59 minutes of arc. (A degree contains
60 minutes).
------------------------------------------------------------------------

What are the actual indications of its position? No one questions that
it was in Aries throughout the Vision, for this is often indicated,
sometimes directly, as in _Inf._ i. 38-40, sometimes by mentioning
Taurus as the sign following the sun,[513] or Pisces as the sign
preceding.[514]

------------------------------------------------------------------------
[513] _Purg._ xxv. 2, 3.

[514] _Inf._ xi. 113; _Purg._ i. 21, xix. 4-6.
------------------------------------------------------------------------

There are four detailed descriptions:—

(1) On the first morning, the sun rose among those stars which were
with him at the Creation.[515] As we have seen, this may mean merely
some point in Aries, or the first point of Aries, at which the sun was
thought to have been placed when created.

------------------------------------------------------------------------
[515] _Inf._ i. 38-40.
------------------------------------------------------------------------

(2) On the seventh day it rose near a point where three crosses are
formed by the intersection of four circles.[516] One naturally thinks
of the horizon as one of these circles; the equator and ecliptic, whose
intersection define the equinox, suggest themselves as two more; the
fourth is doubtless the colure which passes through the equinoctial
points and the poles, although curiously enough this is not mentioned
by Ptolemy or Alfraganus, who only speak of the solstitial colure. Fig.
51 shows how the horizon makes a cross with each of the other three
when the equinox is upon it. The sun is at the point of intersection
when rising with the equinox, and it was _near_ there when it rose
this morning—“quasi.” It was therefore near, but not exactly at the
equinox, and we know that it was the vernal, not the autumnal equinox,
from the many allusions to Aries.

------------------------------------------------------------------------
[516] _Par._ i. 38, 39.
------------------------------------------------------------------------

(3) When Dante rises to the sun (on the same day) he directs our
attention once more to this point where “the one motion strikes the
other,” that is, where the ecliptic—the oblique circle which bears the
planets—branches off from the equator, and he reminds us of the supreme
importance of this divergence. The sun, he says, was in this place. He
does not mean at the exact point of intersection, or this passage would
be in flat contradiction to the last: “quella parte”[517] is no more
precise than “quelle stelle,”[518] and means only this part of the sky,
or the constellation of Aries. The words which follow not only specify
that it was the spring equinox, but suggest that the sun had already
traversed several of those spirals which bring him to us earlier each
morning, _i.e._ it was several days after the equinox.[519]

------------------------------------------------------------------------
[517] “That part.”

[518] “Those stars.”

[519] _Par._ x. 7-33.
------------------------------------------------------------------------

(4) On the same day the sun was “one sign and more” removed from some
point in Gemini.[520] This is very vague, but at least the sun cannot
now have been at the first point of Aries, or it would have been two
whole signs from even the first degree of Gemini.

------------------------------------------------------------------------
[520] _Par._ xxvii. 86, 87.
------------------------------------------------------------------------

It seems, then, that we cannot possibly agree that the sun was at the
equinox throughout the poem. It is clear that it was past the equinox
towards the end; but from these four passages we cannot be sure whether
it was there on the first morning, or whether it moved through some
undefined part of Aries during the Vision.

One consideration gives us some help, however. We know from _Inf._
xxi. 112-114 that the first day was either March 25, which was believed
in the Middle Ages to be the true anniversary of the Crucifixion, or
Good Friday, which was kept by the Church as such. March 25 is four
days after the date which the Church still kept as the day of the
Equinox (March 21), and 13 days after the true equinox, which at this
time fell on March 12. Good Friday also almost inevitably must fall
after the equinox, since Easter follows the full moon which follows
the equinox. It is true that some of Dante’s readers may still have
regarded the old traditional date of March 25 as the true day of the
equinox, and possibly it was to suit all shades of knowledge that he
left the sun’s position vague; but he himself certainly knew better,
and probably had March 12 in his mind. Then those who held to March 25
might consider the sun as exactly at the equinox on the first day of
the Vision, but all better-informed readers and Dante himself must have
regarded it as somewhat past this point. If we take it that, _e.g._,
it was a week past the equinox, the sun was in about 7° of Aries, and
this position agrees with the four crucial passages mentioned above.
The stress laid on the equinox seems to demand that the sun should be
at least as near it as this on the first day; and a week later it would
have reached the middle of Aries, which is the position we assigned to
it from a discussion of _Par._ xxvii. 86, 87.

This also agrees well with the course of the moon in the zodiac, which
must depend upon the sun’s. We have seen that she was opposite the
sun on the first morning, that her light paled the first-risen stars
of Scorpio while she was yet beneath the eastern horizon three days
later, and that she was proceeding south on the following night. If
the sun was in the 7th degree of Aries on the first morning, the moon
must have been in the 7th degree of Libra; her mean daily motion of 13°
would bring her to the 16th degree of Scorpio three days later and to
the last degree on the day following; so even if we allow a deviation
of a few degrees from the average, she was just where she should have
been on each occasion. We have assumed for convenience that she became
full and was opposite the sun just as she set on the first morning, but
this may have happened at any time during the previous night (in the
Forest): Dante has not specified the hour, and it is of no consequence,
since the indications of time by the moon must necessarily be vague.

The time of sunrise will still differ little from 6 o’clock, a week
after the equinox. In London it is a quarter of an hour earlier, but
the difference is less in Italy, and still less in the latitude of
Jerusalem.

Besides the sun and moon, two of the planets are mentioned as in a
particular place among the stars.

Venus, before sunrise on the fourth morning, is seen among the stars of
Pisces;[521] and she is also mentioned as a morning star before sunrise
on the seventh day.[522]

Saturn is in Leo. “Il petto del Leone”[523] may mean the western part
of the Lion, the part which first rises and contains the head and
breast, or it may refer to the star Regulus, which is called by Ptolemy
and Alfraganus “Cor Leonis.”[524] “Sotto il petto”[525] may mean the
position of the planet as seen projected in the sky or a map, that
is, a little south of this part of the constellation; more probably,
perhaps, Dante is thinking of the supposed position of Saturn’s sphere
_below_ that of the stars.[526]

------------------------------------------------------------------------
[521] _Purg._ i. 21.

[522] _Purg._ xxvii. 95.

[523] “The Lion’s breast.” _Par._ xxi. 14.

[524] “The Lion’s Heart.”

[525] “Beneath the breast.”

[526] _Cf. _Purg._ xxxii. 56, 57, where the sun is spoken of as under
another star.
------------------------------------------------------------------------

Mars is spoken of as having returned to his own Lion a number of
times: “al suo Leon ... venne,”[527] but this does not necessarily
imply that he was in that constellation at the time.

Mercury and Jupiter are not noted as seen anywhere in the sky, nor does
Dante say in what constellation they were when he entered them with
Beatrice.

There are a number of pitfalls into which Dante might have stumbled,
with this disposition of the skies, and the change to the southern
hemisphere; and that he has avoided all is as clear a proof of his
familiarity with astronomical phenomena as the positive evidence of his
truthful, consistent descriptions. For instance, he might very well
have represented the cold planet Saturn as actually aiding the cold
moon in driving away the heat of the day during the night, in _Purg._
xix. 1-3, instead of only saying “talor da Saturno;”[528] but if so,
this would have been inconsistent with the position of Saturn in Leo,
since Leo was below the horizon when dawn was drawing near and Pisces
was rising. Again, we have already mentioned that he evidently did not
forget that it was autumn in the southern hemisphere. He never suggests
that it was spring in Purgatory, and in the passage quoted above, where
he describes sunrise at the March equinox, saying that the sun then
moves “con miglior corso e con migliore stella,”[529] this happiest
effect on the world is restricted to “mortals,” who as he thought all
dwelt in the northern hemisphere, “surge ai mortali.”[530] I do not
mean that the expression was used for this reason, but it is an example
of how instinctively he avoided mistakes into which any other author
would almost certainly have fallen.

------------------------------------------------------------------------
[527] “To his Lion has come.” _Par._ xvi. 37, 38.

[528] “Sometimes by Saturn.”

[529] “With a better course and better star.” _Par._ i. 40.

[530] “Rises upon mortals.” _Par._ i. 37.
------------------------------------------------------------------------


6. THE ASSUMED DATE OF THE VISION.

Even among Dante enthusiasts there must be many who are astonished
at the warmth of the controversy concerning the assumed date of his
Vision. To know whether he feigned himself to have entered the Inferno
with Virgil in March or in April, in the year 1300 or in 1301, really
does not help us to appreciate the music of his verse nor the depth
of his thought; yet a wealth of learning and research has been poured
out upon this problem, and some commentators seem ready to defend
their opinions with their lives, if that would avail to convince their
readers!

The date is indeed intimately connected with the narrative of the
_Divine Comedy_, since there are constant allusions to current events.
By choosing a year earlier than the time at which he was writing, Dante
is able not only to tell the spirits what is passing on the earth they
have left, but to endow them with the power of prophesying to him
events which are to come.[531] The peculiar interest of the problem for
us just now is that astronomy has been called in to solve it. We have
seen that the positions and movements of the heavenly bodies are all
consistent with one another in his poem, but it is interesting to ask
whether they are merely a consistent fiction or whether they correspond
with facts. Did Dante arrange his moon and planets according to his
feeling for scenery and the convenience of his time references, or did
he take the positions as they really were at some particular date? If
so, the full moon, Venus a morning star in Pisces, and Saturn in Leo,
all together near a spring equinox, ought to help to fix that date.

The year which is almost universally accepted, by the oldest as well
as the most modern commentators, is 1300, chiefly on the authority of
_Inf._ xxi. 112-114. Here Malacoda says that yesterday (the day of
Dante’s entering the Inferno) it was 1266 years since the earthquake
which accompanied the Crucifixion (see p. 370). Adding to this the 34
years which Dante has told us he believed to have elapsed between the
Nativity and the Crucifixion,[532] we get 1266 + 34 = 1300. And the day
is either the Church Festival commemorating the Crucifixion, _i.e._
Good Friday, which in 1300 fell on April 8, or March 25, which was
believed to be the actual anniversary.

------------------------------------------------------------------------
[531] _Inf._ x. 100-105.

[532] _Conv._ IV. xxiii. 96-98.
------------------------------------------------------------------------

If this is the right interpretation of the passage, we may say at once
that Dante’s astronomical data are imaginary, for the moon was not full
on the night preceding either of these dates, but on March 5, and April
4: Saturn was indeed in Leo, but Venus was so near the Sun as to be
invisible in March, and began to appear as an evening star in Taurus on
about the 9th of April.

These positions were all carefully calculated by Prof. Angelitti, who
is a professional astronomer as well as a Dante scholar; and he made
the thrilling discovery that the positions agree wonderfully well for
the year 1301! In this year the moon was full on the early morning of
the 25th of March; Venus entered Pisces three days later, and was a
morning star, near her greatest elongation west, and very brilliant;
Saturn was not only still in Leo but was just three degrees west of
Regulus; and Mars was also in Leo.

If the anniversary of the Crucifixion means Good Friday, the day would
be March 31 in 1301, and the moon would be wrong, but March 25 has some
claims to be considered the more probable date. A fixed calendar date
is more appropriate to use for calculating an exact number of years
than a changing festival, which might rather be regarded as an “ideal
date.”[533] Moreover, March 25 is suggested by the allusion to the
Creation in the opening Canto; this day was also the traditional date
for the spring equinox,[534] and it was one of the most important days
in the year to Florentines, being their New Year’s Day as well as Lady
Day.

------------------------------------------------------------------------
[533] Moore, _Studies in Dante_ iii. p. 146.

[534] See p. 177.
------------------------------------------------------------------------

We know that the idea of writing his great work was in Dante’s mind
even when he wrote the last words of the _Vita Nuova_,[535] and we need
only suppose that he was thinking of it when he looked at the sky on
the evening before Lady Day in 1301, that he saw the full moon, and
the two bright planets Mars and Saturn making a striking asterism with
Regulus; also that in the early dawn about the same time he rejoiced in
the sight of Venus veiling the Fishes in the east.

------------------------------------------------------------------------
[535] _V. N._ xliii. 1-11.
------------------------------------------------------------------------

But is this attractive theory admissible? Can we take Dante’s words
elsewhere as referring to the year 1301?

Take first the one passage in which he explicitly states the day and
year, the words of Malacoda quoted above. This is usually taken to
indicate the year 1300, as shown above (p. 410), but it is easy to
interpret it another way—thus: 1300 years had been completed since the
Nativity on the day Dante entered the Inferno. Now the year 1 is not
one year after the Nativity, but the year of the Nativity itself; hence
the year 2 is one year after, the year 3 two years after, ... the year
1300 is 1299 years after, and the year 1301 is 1300 years after. The
year 1300 was completed on March 25,[536] and the date then changed,
according to Florentine usage, to 1301. (It had already been called
1301 for three months, according to Roman usage, so fortunately for us,
there is no disagreement between the two calendars from this part of
the year).

------------------------------------------------------------------------
[536] Exactly at midday, moreover, according to one system then in
vogue, though it seems to have been more usual to begin the day at
sunrise.
------------------------------------------------------------------------

It must also be noted that in several old MSS., considered
authoritative by some of the very early commentators, the passage
reads:—“Mille dugent _’uno_ con sessanta sei.”[537] Although it is
impossible to believe that Dante wrote such a faulty line, this shows
that some early copyist felt a difficulty either in accepting the
date 1300 or in understanding how Dante arrived at it by Malacoda’s
computations. This passage, therefore, is inconclusive for 1300 or 1301.

------------------------------------------------------------------------
[537] “A thousand two hundred _and one_, added to sixty-six.”
------------------------------------------------------------------------

Then there is the first line of the _Divina Commedia_ “Nel mezzo del
cammin di nostra vita,”[538] which is usually taken to mean that
Dante was in his 35th year, since in _Conv._ IV. xxiv. 30, 31, and
xxiii, 88-94, he says that in normal natures the “punto sommo,” the
“colmo,”[539] of the Arch of Life is reached at this age. But is it to
be taken as indicating a precise year? If so, it points to one which
has never been suggested for the Vision, so far as I know, for in
another passage of the _Convivio_ he says when speaking of his exile,
that he had lived in Florence “fino al colmo della mia vita,”[540]
and we know that the year of his exile was 1302. But if we look again
at the discussion concerning the arch of human life, we find that the
whole period of “gioventute,”[541] which is from the 25th to the 45th
year “veramente è colmo della nostra vita”[542] (_Conv._ IV. xxiv.
22, 23). If, nevertheless, it is said that the “mezzo del cammin di
nostra vita” means Dante’s 35th year, we must know the date of his
birth with certainty before we can deduce the year at which he had
reached this age. And this is not quite easy. This very line is used
indifferently to show that he was born in 1265 because the date of
the Vision was 1300, or that the date was 1300 because he was born in
1265! No registers of births or baptisms were kept in those days. Most
of the old biographers give 1265 for the date, but not all, and some
of those who do betray ignorance or confusion in the matter: Boccaccio
says the year 1265, when Urban the Fourth was Pope, yet Urban we know
died in 1264; Lionardo Bruni says “1265, a little after the return to
Florence of the Guelfs, who had been in exile by reason of the defeat
of Montaperti,” but this return was in September 1266! Dante himself
says that his ancestors shared in this exile,[543] and as he also often
refers to the fact that he was born in Florence,[544] it is difficult
to see how that could have been in 1265.

------------------------------------------------------------------------
[538] “Midway in the journey of our life.”

[539] “The highest point,” the “summit.”

[540] “Until the summit of my life.” _Conv._ I. iii. 24, 25.

[541] “Youth.”

[542] “Is in truth the summit of our life.”

[543] Farinata alludes to the two Guelf banishments of 1248 and 1260.
_Inf._ x. 42-50.

[544] _Conv._ I. iii. 22-24; _Inf._ xxiii. 94, 95, etc.
------------------------------------------------------------------------

Again, he says that there was a difference of less than 8 months
between the age of Beatrice and himself (she was 8 years 4 months old
when he was nearly nine),[545] that she died in June 1290,[546] and was
then on the threshold of her “second age,”[547] that is in her 24th
year, or 23 years old. This gives 1267 for the year of her birth, and
he must have been born in the same or the preceeding year. Historical
documents show that Dante spoke in the Council of the Hundred in 1295,
and Brunetto Latini says no man could hold office in Florence under
thirty years of age; but Brunetto wrote in exile in France and died in
1290, and in a translation from his original French into Italian the
age has been altered to 25, so it is possible that the age had been
lowered before 1295.[548] There remains the story told by Boccaccio,
that a Ser Piero di Messer Giardino (a notary whose name occurs in
legal documents of the time), heard from Dante himself shortly before
his death that he had been 56 years old in the preceding May. The date
of his death is unanimously given as 1321, so this story, if we may
accept it as authentic, is one clear piece of evidence that Dante was
born in 1265.

------------------------------------------------------------------------
[545] _V. N._ ii. 1-15.

[546] _V. N._ xxx. 4-13.

[547] _Purg._ xxx. 124, 125; _Cf. Conv._ IV. xxiv. 11-13.

[548] Imbriani: _Quando nacque Dante?_ and _Che Dante
probabilissimamente nacque nei MCCCLXVII_.
------------------------------------------------------------------------

On the whole, we must say that it is doubtful whether the “mezzo del
cammin” means Dante’s 35th year, and if it does, we are not certain
that he reached that age in 1300.

Another passage which is often quoted as clearly indicating the year
of the Jubilee, 1300, for the assumed date of the Vision is Casella’s
explanation of his late arrival in Purgatory.[549] Dante is surprised
to witness this arrival, knowing that it is some time since his
friend’s death; and Casella replies that the Angel of the Passage had
refused many times to bring him, until three months ago, when every one
who wished to come had been graciously received. This is believed to
refer to the Bull of Pope Boniface published at Christmas 1299, that is
just three months before March 1300. But this Bull gave no indulgence
to the dead; it was in favour of those who performed certain spiritual
exercises in the churches of Rome during the Jubilee year. On the other
hand, there was a Bull published just a year later, which was for the
benefit of departed souls: it extended the indulgences to those who
had died on their way to Rome, or before the spiritual exercises were
completed there. We do not know when Casella died, but if it was some
time in 1300, with his purpose of gaining the indulgence unfulfilled,
the Angel’s refusal at first, and acceptance afterwards—after December
1300—and his arrival in Purgatory in March 1301, would be explained.
The fact that his arrival was still three months after the Bull, and
that all without exception were welcomed by the Angel, are difficulties
which apply to both interpretations. But perhaps that just given is a
little too clever. It is most natural to consider the Indulgence as the
famous one of 1300, and to understand that in the Jubilee year the way
of salvation was made easier for all souls, living or dead.[550]

------------------------------------------------------------------------
[549] _Purg._ ii. 91-103.
------------------------------------------------------------------------

[550] For this point and a full discussion of the date, especially
from the astronomical data, see Angelitti’s _Sulla Data del Viaggio
Dantesco_, and _Sull’ anno della Visione Dantesca_, and Moore’s “The
Date assumed by Dante for the Vision of the ‘Divina Commedia,’”
_Studies in Dante_ III.

If however these, and many other passages quoted in the controversy,
are unconvincing, the same cannot be said of Cunizza’s “Questo
centesim’ anno.”[551] Prof. Angelitti’s suggestion that she was
reckoning by the Easter year, which was used in some parts of France
and Italy, so that the date was still 1300 for her, though for most
Italians it was 1301, is too ingenious; and it is hard to believe that
she means “this century year” applying it to 1301. Though this might
be correct, it is clear that 1300 was regarded as the century year,
because the words “centesimo anno” occur in the Bull of Boniface VIII.
with reference to the year 1300. This then speaks strongly and clearly
against our astronomical theory of 1301.

------------------------------------------------------------------------
[551] “This hundredth year.” _Par._ ix. 40.
------------------------------------------------------------------------

The historical events alluded to in the _Divine Comedy_ are so often
of unknown date to us, that few of them help as much as might be
expected. Judge Nino’s widow remarried on June 24, 1300, and as he
speaks of her as having already put off her widow’s weeds,[552] this
might indicate that we are in 1301, but it is not conclusive, since
they would probably be discarded three months before she was actually
the wife of another. On the other hand, Can Grande della Scala, who is
said in a fourteenth century chronicle to have been born on March 9,
1291, is described as only nine years old.[553] Dante might possibly
have been mistaken by a year in the date of his birth, but he cannot
have been ignorant of the death of his friend Guido Cavalcanti. The cry
of anguish from Guido’s father will be remembered by all readers of the
_Inferno_, after Dante has spoken of his friend in the past tense:—

------------------------------------------------------------------------
[552] _Purg._ viii. 74.

[553] _Par._ xvii. 80, 81.
     “Di subito drizzato gridò: Come,
      Dicesti _egli ebbe_? Non viv’ egli ancora?
      Non fiere gli occhi suoi lo dolce lome?”[554]

[554]
    “Up starting suddenly he cried out: How
    Saidst thou? ‘_he had_?’ Is he not still alive?
    Does not the sweet light strike upon his eyes?”
                              _Inf._ x. 67-69.
------------------------------------------------------------------------

And as Dante hesitates a little, Cavalcante sinks back into his tomb
of punishment, and does not reappear. Before Dante leaves the place,
feeling compunction, he charges Farinata to tell the father that his
son is still among the living, and that the sinister hesitation was
due to another cause than he thought. Now it is beyond dispute that
Guido died in August 1300, for he was buried in the cemetery of St.
Reparata in Florence on August 29, 1300, according to official records
still extant;[555] and Dante had a share in banishing him amongst other
exiles to the unhealthy place where he contracted the illness of which
he died. The year 1300, in which Dante held the official position
which obliged him to do this, was burned into his mind, as we see in
his letter, mentioned by Lionardo Bruni, in which he says that all his
misfortunes sprang from the time of his priorate.

------------------------------------------------------------------------
[555] Toynbee’s _Dante Dictionary_, under “Cavalcanti.”
------------------------------------------------------------------------

How then can we believe that he here imagines himself speaking in the
spring of 1301, unless we assume that Cavalcanti had really guessed the
true cause of his hesitation, and that what Dante said afterwards was a
kindly lie? Is this in character with his uncompromising, even ruthless
straightforwardness? Unless therefore some really satisfactory way of
escape can be found from this incident and the “centesim’ anno” I fear
we must reluctantly abandon the theory of 1301, championed so skilfully
by Angelitti and others, and must agree with the majority that Dante
means us to understand the year 1300.

The early commentators seem to have taken for granted that Dante was
correct in his astronomical data, without taking any particular trouble
to verify them. Jacopo della Lana in commenting _Par._ xxi. 14 says
that in 1300 in the month of March Saturn was in Leo, and was in the
8th degree of that sign; and in order that we should know what was the
disposition of the whole sky at that time he further informs us that
Jupiter was in Aries in the 24th degree, and Mars in Pisces in the
11th degree, that the sun was near the beginning of Aries, and Venus
in Pisces (these two are evidently taken simply from Dante). Mercury
was in Virgo (with the sun in Aries! in this case Mercury would have
been visible nearly the whole night), and the moon in       . Here
there is said to be a blank in all the MSS. The moon was too much for
Della Lana, whether the difficulty was in finding her position or in
reconciling it with that given by Dante. The Ottimo and Benvenuto da
Imola copy Della Lana with little change, both giving the positions
of Saturn, Jupiter, and Mars in degree and sign, but the sun only as
near the beginning of Aries, Venus in Pisces, and Mercury in Virgo.
(It is astonishing that neither should have noticed this gross error.)
Benvenuto boldly adds that the moon was in Libra, doubtless because
Dante’s description so required it at the beginning of his poem.

Nor do these early commentators seem to feel any difficulty about the
date on which the Vision began. From _Inf._ i. 38-40 they generally
conclude that it was the day of the equinox, which they say vaguely
fell in the middle of March “mezzo Marzo,” and from _Inf._ xxi. 112-114
all except Boccaccio (who interprets March 25) take it to be Good
Friday.[556] No discrepancy seems to have been felt here: they merely
remark that in 1300 Easter fell in March, and more than two hundred
years passed before anyone pointed out that this was wrong.

------------------------------------------------------------------------
[556] Moore, _Studies in Dante_ III. p. 146.
------------------------------------------------------------------------

At last a work appeared in 1554, called “_Del Sito, Forma, et Misure
dello Inferno di Dante_,” in which the author, Giambullari, remarked
that according to astronomical calculations the Paschal Moon was not
full on the night between Thursday and Good Friday in 1300, but on the
morning of April 5th. This excited a good deal of interest, and many
theories have since been put forth to reconcile Dante’s astronomical
data with the facts of the year 1300.

Dr. Moore thinks the date of entering the Inferno was Good Friday,
April 8, 1300, but that Dante uses instead of the real moon the
ecclesiastical moon, which, as we know, is a conventional body
revolving according to Meton’s cycle, and sometimes appearing on tables
as full two or three days before or after the real Full Moon. Dr. Moore
finds that this ecclesiastical moon, was full on April 7, 1300.[557]
But would Dante trouble about the ecclesiastical moon, and would his
readers know anything about it? Its only use was for determining
Easter, and this was done for the people by the Church. The real moon
was extremely important for astrologers, for whose benefit Tables and
Almanachs were chiefly drawn up; the real moon was useful to everyone
as light-giver and time recorder. It is surely inconceivable that a
Florentine who wished to arrange a midnight festival, or to start on a
night-journey, would consult a calendar to find out on what date the
_ecclesiastical_ moon would be full! And the ecclesiastical moon does
not alter the position of Venus.

------------------------------------------------------------------------
[557] “The Astronomy of Dante,” in _Studies_ III., and _Time References
in the Divina Commedia_.
------------------------------------------------------------------------

According to another suggestion, Dante followed a tradition as to the
position of all the “seven planets” at the Creation, and for this
reason not only was his sun in Aries, but the moon full and opposite,
and Venus in Pisces. Venus is said to have this position in a picture
of the Creation in a Church at San Gemignano.[558] Compare also
Milton’s moon at her creation:—

------------------------------------------------------------------------
[558] Note on _Purg._ i. 19-21 in the “Temple” edition of Dante.

             “ ... Less bright the moon,
    But opposite in levelled west, was set,
    His mirror, with full face borrowing her light
    From him.”[559]

[559] _Par. Lost_ vii. 375-378.
------------------------------------------------------------------------

Or again, it is sometimes held that the day and all the celestial
positions are ideal. Dante means us to understand that the first day
of his Vision was Good Friday, but without troubling as to what day it
fell on in 1300; the equinox and the full moon are naturally connected
with Good Friday, since they determine Easter; Venus is connected with
the idea of dawn, and when the Sun is in Aries the morning star may
well be in Pisces.

Either of these views might be correct, and no one will dispute a
poet’s right to arrange his skies as he thinks fit, if he is consistent
with them, as Dante was. But how did these positions, if they are
purely imaginary, come to coincide exactly with the real positions of
1301?

If we examine the positions of 1301, and accept nothing that is
doubtful in Dante’s own words, what does the coincidence amount to?
Saturn was near Regulus, but he was also in the forepart of Leo in
1300, and we are not sure that Dante means more than this; Mars was in
Leo, but we are not sure that Dante wanted him there;[560] the moon
was full on the morning of March 25, but we are not sure whether Dante
means March 25 or Good Friday. Venus was a morning star in Pisces, and
this till very lately was the one astronomical fact incontestably in
favour of 1301 and against 1300.

------------------------------------------------------------------------
[560] See p. 407.
------------------------------------------------------------------------

But in 1908 there was printed in Florence, for the first time, a
mediæval Almanach, which suggests so simple an explanation of this
most striking coincidence that it seems to leave nothing more to be
said for the 1301 hypothesis. This Almanach, which has been published
under a title which perhaps takes things a little too much for
granted—_Almanach Dantis Aligherii_—was compiled by a learned Jew,
Jacob ben Machir ben Tibbon, who was born in Marseilles about 1236,
and died at the beginning of the fourteenth century. Using the Toledan
Tables, he constructed this so-called perpetual almanach, which gives
the positions of sun, moon, and planets, at intervals of a few days for
whole cycles of years. Each has a cycle of a different length, that
of Venus for instance being 8 years, as on the Babylonian tablets of
ephemerides; and at the end of each cycle nearly the same positions
come over again. It was written in Hebrew, and translated into Latin
by an unknown author, and must have been popular, since there were
an immense number of Latin MSS. in the fourteenth century. In the
original, all the cycles begin in 1301, but in the Latin they begin in
1300, _except the cycles of Venus and the sun, which begin in 1301_.
Yet 1301 is not written over the first column for Venus, but merely 1,
or nothing at all, or even in some copies 1300, and in both the Hebrew
and Latin prefaces the beginning of all the cycles is stated to be
1300.[561]

------------------------------------------------------------------------
[561] Preface to _Almanach Dantis Aligherii_, Boffito and Melzi d’
Eril.
------------------------------------------------------------------------

If, therefore, Dante looked up the position of Venus in this almanac,
he would very naturally take the 1301 positions for 1300, and he would
find that Venus was in Aquarius throughout March, until the 27th, when
she passed into the sign of Pisces, and therefore was a morning star
during the whole month and also in April. And he would find that Saturn
was in the 7th and 8th degrees of Leo in March and April 1300 (which
was very nearly correct).[562]

------------------------------------------------------------------------
[562] It is important to observe that this suits the description of
the “Lion’s breast” better than the 20th and 21st degrees (Almanach
positions for 1301), if Dante, as usual in the _Divina Commedia_,
identifies the constellation with the sign.
------------------------------------------------------------------------

It appears then that while certain expressions used in the _Divine
Comedy_ prove clearly that 1301 is not the year assumed as the date of
the Vision, the astronomical argument in favour of it is not strong
enough to be convincing, especially in the light of this recent
discovery.

Granting that 1300 was the year, what was the day? Probably not March
25, for the early commentators, excepting only Boccaccio in one
passage, are all in favour of Good Friday, and Dante might see in the
Almanac that the moon was not full on that date. But neither was she
full on the actual date of Good Friday, which fell on April 8 in 1300;
moreover the sun was then so far advanced in Aries that seven days
later, when Dante describes it as a little past the equinox, it would
really have been in Taurus. The third and only possibility is to accept
the theory that his moon and his day were ideal; that is, he simply
assumed Good Friday and a full moon to occur together soon after the
equinox, with which both are so intimately associated. The date of
Easter is not given in the old almanac, and we have seen that the early
commentators who knew that the equinox fell in “mezzo Marzo”[563] were
content to accept Easter as falling in that month also. We must not
forget the convenience of an equinox and a full moon for simplifying
the time references also.

------------------------------------------------------------------------
[563] The middle of March.
------------------------------------------------------------------------

We conclude, then, that the year chosen by Dante was 1300 (as has been
most generally believed), and the day Good Friday, which he assumes
to have fallen about a week after the equinox, and at a time of full
moon. Saturn in his poem, and also in fact, was in Leo; Venus was not
actually a morning star, nor in Pisces, but he may have been led to
assign this position to her through an error in a contemporary almanac.

I must confess to a great feeling of disappointment in coming to the
conclusion that Prof. Angelitti’s enticing theory must be rejected, but
a careful study of Dante’s own words, and Prof. Boffito’s discovery
of the “Almanach perpetuum ad annum 1300 inchoatum” seem to leave no
other choice. Last April,[564] when helping to photograph Halley’s
Comet in beautiful early dawns, this problem was much in my mind. Venus
once more had the Fishes in her train, and oddly enough Good Friday
had fallen on March 25! I could not help wishing that these things had
happened in 1300 as well as in 1910!

------------------------------------------------------------------------
[564] This was written in 1910.
------------------------------------------------------------------------

If in spite of all arguments to the contrary, any readers are convinced
that Dante’s celestial positions were taken from the real skies, it
remains to them to imagine that he saw them in March of 1301 and wove
them into the narrative of his poem, although for some reason he
adopted another date.

The following tables (pp. 425-26) summarize the foregoing pages. It
will be noted with what appropriate symbolism Dante enters Hell on the
evening of Good Friday, spends that night and the whole of Saturday in
the depths, and rises out of them on Easter Day before the dawn.

For although he reaches Earth’s centre on Saturday evening by Jerusalem
time, the change of hemisphere there makes his time suddenly go back
twelve hours, so that it is again Saturday morning, and he spends the
day and night of Saturday (Purgatory time) in climbing to Earth’s
surface.

DAYS OF THE VISION AND POSITIONS OF THE SUN, MOON, AND PLANETS.

     _Dante’s |Jerusalem|Purgatory| Positions of Sun,_|
    _Journey. |  Time.  |  Time.  | Moon and Planets  | References._
              |         |         |     _in Zodiac._  |
    ----------+---------+---------+-------------------+-----------------
              | Night   |         |Moon full in Libra,|_Inf._ xx. 127.
              |         |         |  about 7th degree |
              |Day I.   |         |Sun in Aries,      |_Inf._ i. 38-40.
    Forest    |Good     |         |  about 7th degree |
              |Friday   |         |                   |
              |(1300)   |         |                   |
    ----------+---------+---------+-------------------+-----------------
              | Night   |         |                   |
    Inferno   |Day II.  |         |                   |
              |Saturday |         |                   |
    ----------+---------+---------+-------------------+-----------------
              |Night    |Day III. |                   |
              |         |Saturday |                   |
    Earth’s   | Day     |  in     |                   |
     Interior |(Sunday) |Purgatory|                   |
              | Easter  | Night   |                   |
              |  Day    |         |                   |
              |         |Day IV.  | Venus in Pisces   |_Purg._ i. 19-21.
              |         |(Sund.)  |   at dawn         |
              |         |Easter   |                   |
              |         | Day     |                   |
              |         |  in     |                   |
              |         |Purgatory|                   |
              |         |         |                   |
              |         | Night   |Moon in the middle |_Purg._ ix. 1-6.
              |         |         |  of Scorpio       |
    ----------+---------+---------+-------------------+-----------------
              |         |Day V.   |                   |
              |         |(Mond.)  |                   |
              |         | Night   |Moon at end of     |
              |         |         |  Scorpio or       |
    Purgatory |         |         |  beginning of     |_Purg._
              |         |         |  Sagittarius      |  xviii. 79-81.
              |         |Day VI.  |                   |
              |         |(Tues.)  |                   |
              |         | Night   |                   |
    ----------+---------+---------+-------------------+-----------------
    Earthly   |         |Day VII. |Sun in the middle  |_Par._ i. 37-44;
     Paradise,|         |(Wed.)   |  of Aries         |  x. 7-33;
     planetary|         |         |Saturn in Leo      |  xxvii. 86,87.
     & stellar|         |         |                   |
     spheres  |         |         |                   |
    ----------+---------+---------+-------------------+-----------------
    Primum    |         |Day VIII.|                   |_Par._ xxi.
     Mobile   |         |(Thur.)  |                   |   13-15.
     and      |         |         |                   |
     Empyrean |         |         |                   |




Summary.


                        _Arguments for 1300 or 1301._
                 _From Expressions and Incidents in the D.C._

    Malacoda.             | Inconclusive: method of reckoning uncertain.
      _Inf._ xxi. 112-114.|
                          |
    “Nel mezzo del        | Inconclusive: a precise year possibly not
    cammin.”              |   indicated, and date of Dante’s birth not
      _Inf._ i. 1.        |   certainly known.
                          |
    Casella.              | Inconclusive: may refer to Bull of 1299,
      _Purg._ ii. 98-99.  |   but possibly of 1300.
                          |
    Can Grande.           | For 1300: Can Grande 9 years old in
      _Par._ xvii. 80, 81.|   March 1300.
                          |
    Cunizza.              | For 1300: “questo centesim’ anno” can only
      _Par._ ix. 40.      |   mean 1300.
                          |
    Nino’s widow.         | Inconclusive: might put off widow’s weeds
      _Purg._ viii. 74.   |   before re-marriage.
                          |
    Guido Cavalcanti.     | For 1300: Guido, Dante’s intimate friend,
      _Inf._ x. 111.      |   died in August 1300.


The Astronomical Data.

             (_True Equinox, March 12. Ecclesiastical, March 21.
                          Traditional, March 25_).

     _In D.C.       |   On Good Friday, 1300.      | On March 25, 1301._
                    |                              |
    SUN near        |Day assumed to fall soon after|Date of traditional
     EQUINOX.       |  equinox (actually April 8.) |  equinox (13 days
                    |                              |  after true
                    |                              |  equinox).
                    |                              |
    MOON full on    |Assumed full, since Easter    |Full.
     first day.     |  associated with equinox and |
                    |  full moon. (Actually full   |
                    |  March 5, and April 4.)      |
                    |                              |
    VENUS in Pisces |Supposed in Pisces from error |Entered Pisces
     on 4th day.    |  in contemporary almanac,    |  March 27.
                    |  confounding 1301 with 1300. |
                    |                              |
    SATURN “on the  |In forepart of Leo,           |In Leo, 21st degree
     Lion’s breast.”|  8th degree of the sign.     |  of the sign,
                    |                              |  close to Regulus.
                    |                              |
    MARS possibly   |Not near Leo.                 |In Leo.
     intended to be |                              |
     in Leo.        |                              |

Early commentators understand Good Friday, not March 25.


_VII. THEORETICAL AND SPECULATIVE ASTRONOMY._

    “Thou shalt learn the burning nature of the pure
    clear sun, thou shalt hear the wandering nature
    of the round-eyed moon, and thou shalt learn of
    the surrounding heaven, whence it arose, and how
    Necessity guiding it compelled it to hold fast the
    bounds of the stars.”
                                    _Parmenides._


1. THE SPHERES.

Dante’s astronomical phenomena, though they are just the same that are
familiar (or ought to be familiar) to us, have led us into some strange
by-ways, because they are so intimately connected with his works of
imagination. His astronomical theories, by which these phenomena were
explained, will also take us into paths which are now seldom trodden
by astronomers or others, because mediæval astronomy was mingled with
magic, with metaphysics, and with religion, in a way which seems very
strange to us.

The second treatise of the _Convivio_ has for its text the Ode which
is quoted in _Paradiso_ viii. 37, “Voi che intendendo il terzo ciel
movete.”[565] When speaking of the literal meaning of this Ode, Dante
takes the occasion to discourse on the system of astronomy which he
had learned, and describes how all the apparent movements of the
heavens are explained by postulating the existence of spheres and
epicycles, entering with special detail into the system of Venus, the
third heaven; and later on, when expounding the allegorical meaning of
the Ode, he draws an elaborate comparison between the spheres and the
different branches of science and philosophy, in which he incidentally
gives his readers a good deal of information about the heavens.

------------------------------------------------------------------------
[565]
    “Oh ye whose intellectual ministry
    Moves the third heaven.”
                         (_Carey_).
------------------------------------------------------------------------

From this interesting treatise, therefore, as well as from many
scattered passages in all his works, we learn what Dante thought
were the real movements of the heavenly bodies, their dimensions,
their nature, and the forces which move them; and it forms a valuable
commentary on the _Paradiso_, in reading which he supposes us to
understand the elements of the Ptolemaic system, and the ideas of the
philosophers and the Fathers of the Church concerning the organization
of the Universe.

Of these ultimate truths concerning the heavens, Dante says, very
little can be known, but the little which is within the reach of human
reason, gives more delight (as Aristotle says) than the abundance
and the certainty of other things easier to be understood.[566] This
thought finds an echo in the _Paradiso_, where the poet reminds us of
the beautiful order to be found throughout the universe, and invites us
to contemplate the skill of the architect as shown in the movements of
the planets.[567]

------------------------------------------------------------------------
[566] _Conv._ II. iii. 8-14.

[567] _Par._ x. 1-12.
------------------------------------------------------------------------

Dante knew that great men in ancient days had speculated on the
possibility that it was Earth, and not the skies, that moved in the
diurnal period, but the balance of authority was against them, and they
had been confuted by the Master of those who KNOW,[568] that glorious
philosopher to whom Nature most fully revealed her secrets,[569]
Aristotle. In Treatise III. of the _Convivio_ he gives a clear and
concise account of the theory of Philolaus, and of what he understood
to be the theory of Plato.[570] In the former he seems to have been
struck with the deduction that, if Fire were at the centre of the
Universe, the real motion of fire on Earth, which to us appears always
to ascend, would in reality be a descent towards its own place at the
centre.

------------------------------------------------------------------------
[568] _Inf._ iv. 131.

[569] _Conv._ III. v. 54-56.

[570] _Conv._ III. v. 29-52. See Part I. of this book _Pythagoras and
his Followers_, and _Plato_, for a description of their astronomical
systems.
------------------------------------------------------------------------

Both these hypotheses he had evidently learned from Aristotle’s _De
Cælo_,[571] and when thus presented they seem entirely fanciful; so
although Dante had reverence for both Pythagoras and Plato it is not
surprising that he rejected the systems of both. He adds that it is
not his intention to recount here the arguments by which Aristotle
confutes them and establishes the truth: it is enough for his readers
to know, on so great an authority, that the earth is fixed, and does
not revolve, and is at the centre of the World.

Dante has to confess reluctantly that Aristotle made two mistakes in
his astronomy: he said that there were only eight spheres, those of the
seven planets, and that of the stars, “e che di fuori da esso non fosse
altro alcuno;”[572] also he placed the heaven of the sun immediately
above that of the moon, that is to say second in order, counting from
Earth outward. Aristotle’s loyal admirer hastens to add that these
serious mistakes “questa sua sentenza così erronea”[573] are explicable
and excusable because, as Aristotle himself shows in the _Metaphysics_,
when he treated of astrology he was merely following the opinions of
others. That is to say, he took his facts from others, and they cannot
all be depended upon, but his philosophical deductions are his own, and
are never in error. In the above question of the possible movements
of Earth, we saw (pp. 101-2) that Aristotle’s arguments were almost
entirely drawn from metaphysics.

------------------------------------------------------------------------
[571] See Part I. “Aristotle.”

[572] “And that outside the latter there was no other.” _Conv._ II.
iii. 24, 25.

[573] “This entirely mistaken opinion of his.” _Ibid._ 28.
------------------------------------------------------------------------

There have been many opinions regarding the number and the positions
of the spheres, Dante says, but the truth about them has at length
been found. The scheme which he expounds is that of Ptolemy, modified
by the Arabs and adapted to the doctrines of the Church by Christian
writers. In the _Vita Nuova_ he almost seems to imply that the nine
moving spheres form an article of faith. “Secondo Tolommeo e secondo la
Cristiana verità, nove siano li cieli che si muovono.”[574]

------------------------------------------------------------------------
[574] “According to Ptolemy and according to Christian Truth, nine is
the number of the moving heavens.” _V. N._ xxx. 16-18.
------------------------------------------------------------------------

Quoting from Albertus Magnus, or Averroës, he apparently credits
Ptolemy with the discovery of precession, for he says that it was
Ptolemy who added a ninth sphere to the eight of Aristotle, because
he perceived that otherwise the outer sphere would have a double
movement, and so he felt obliged to assume a sphere beyond the
star sphere which should have only the one simple motion of the diurnal
east to west revolution. The period of this revolution (the sidereal
day) Dante gives as 23 hours and ¹⁴/₁₅ths of an hour, “grossamente
assegnando,”[575] _i.e._ 23 hours 56 minutes, which is the correct
value ignoring the 4 seconds. We know that it was not Ptolemy in fact
who thought it necessary to add a ninth sphere; he was not sufficiently
interested in spheres, since to him they were only mathematical
abstractions: but the Arabs of Baghdad noted that he had added another
_movement_, the discovery of Hipparchus; and they, accepting the
spheres as material instruments of celestial motions, felt obliged to
assume the existence of the Primum Mobile or 9th sphere.

That Dante should believe the spheres to exist as actual entities was
inevitable, for his principal authorities, Greek, Arab, and Christian,
all taught this. And there is abundant evidence that he did think
of them thus. He calls them bodies:—“omnia corpora,”[576] “questi
corpi grandi,”[577] “cerchi corporai,”[578] “il maggior corpo,”[579]
etc. They are transparent, one sphere not obstructing the light from
another;[580] and composed of æther, “questo etera tondo.”[581] They
have a certain thickness, and would be visible if near enough, for
Dante speaks of the inner margin of the Primum Mobile, and says that it
was too far above him for him to have seen it yet, when he was in the
Star Sphere.[582]

------------------------------------------------------------------------
[575] “Roughly speaking.” _Conv._ II. iii. 36-48.

[576] “All bodies.” _Ep._ x. 445.

[577] “These vast bodies.” _Par._ viii. 99.

[578] “Material circles” (here compared with the Angels, who are purely
spiritual). _Par._ xxviii. 64.

[579] “The greatest body.” _Par._ xxx. 39.

[580] _Purg._ iii. 29, 30.

[581] “This rounded ether.” _Par._ xxii. 132.

[582] _Par._ xxiii. 112-117.
------------------------------------------------------------------------

He gives the order of the eight heavens as in Ptolemy, and adds the
ninth, which is only perceived by the diurnal movement of which it
is the cause; and it is called by many the Crystalline, that is, the
diaphanous or completely transparent Heaven.[583] The order of these
spheres has been discovered by observation and reasoning, with the use
of the principles of Perspective, Arithmetic, and Geometry. Dante gives
as an instance the experience of Aristotle, who with his own eyes saw
the moon pass below Mars, and so hide it for some time; and he mentions
also how in eclipses it is evident that the moon is below the sun
(_i.e._ nearer to us).[584]

To these nine spheres of the astronomers, the Catholic Church, “which
cannot lie,” adds a tenth, the Empyrean Heaven, which means the heaven
of flame or light, and is the abode of the blessed spirits and of God
Himself.[585] And here Dante is able to give himself the pleasure of
adding that Aristotle seems to have been of this opinion also; “Ed anco
Aristotile pare ciò sentire, a chi bene lo intende, nel primo _Di Cielo
e Mondo_.”[586] He is no doubt alluding to what Aristotle says about
the existence beyond the finite universe.[587] The whole passage is
thus translated in the “Temple” Dante:[588] “Nor is there any change
of any of those things which are ranged above the outmost rotation,
but they are unchangeable and passionless, enjoying the superlative
existence, and passing in absolute self-sufficiency their eternal life.”

------------------------------------------------------------------------
[586] “And Aristotle also, to one who rightly understands him, seems to
mean the same thing, in his first book of _The Heaven and the Earth_.”
_Conv._ II. iv. 32-34.

[583] _Conv._ II. iv. 1-13.

[584] _Conv._ II. iii. 52-65.

[585] _Conv._ II. iv. 13-16, 30-32. See also _Ep._ x. 448-452.

[587] See p. 97.

[588] _The Convivio of Dante_, “Temple” Edition, note on II. iv.
------------------------------------------------------------------------

The ninth sphere rotates on two poles, which are absolutely fixed,
“fermi e fissi e non mutabile, secondo alcuno rispetto,”[589] the eight
within it have each two poles which are only relatively fixed (for they
move with the movement of the Primum Mobile), and every sphere has an
equator, every point on which is equally distant from the two poles of
rotation, as anyone may see who will turn round an apple, or any other
spherical thing. Any point on the equator moves more quickly than any
other point on the sphere, and each part moves more quickly the nearer
it is to the equator, more slowly as it is far from it and nearer to
the pole, since all the circling is done in the same time, and some
parts have a greater, and some a less distance to go, according to
their distance from the equator. Dante adds that the nearer any part of
a heaven is to its equator, the nobler it is compared with its poles,
for it has more movement, and more actuality, more life, and more form,
and it touches more of the heaven just above, and in consequence is
more noble.[590]

------------------------------------------------------------------------
[589] “Firm and fixed and not moveable, from any point of view.”
_Conv._ II. iv. 50, 51.

[590] _Conv._ II. iv. 68-75.
------------------------------------------------------------------------

Besides these ten heavens there are others which, strictly speaking,
should be included in the number: these are the little spheres which
are called “epicycles” by astronomers, and they also have equators and
poles of rotation, and are fixed on the large spheres, or heavens.
Dante does not enter into any particulars about these, but only
mentions (as belonging specially to the subject in hand) that the
brilliant star of Venus is carried “on the back” of an epicycle, which
is itself fixed on the back of the third Heaven.[591] The apparent
movement of Venus is therefore compounded of no less than four
movements: that of her epicycle, of her whole heaven (the “deferent”
Dante does not name, probably as introducing too technical a word),
of the west to east motion of the star sphere (precession), and the
diurnal. The epicycle of Venus is also called in this treatise, as
we have already seen, “quello suo cerchio che la fa parere serotina
e mattutina, secondo i due diversi tempi,”[592] and the “terzo
epiciclo”[593] is referred to in _Par._ viii. 3.

------------------------------------------------------------------------
[591] _Conv._ II. iv. 78-104.

[592] “That circle of hers which makes her appear as evening and
morning star, according to the two different periods.” _Conv._ II. ii.
3-5.

[593] “Third epicycle.”
------------------------------------------------------------------------

A little further on in the same treatise, Dante tells us the periods
in which all these nine spheres revolve. It is an interesting passage,
and illustrates the poet’s vivid way of bringing home to his own mind
and those of his readers the effects of the different celestial
motions.[594] The ninth sphere, which is the Crystalline or Primum
Mobile, causes by its daily revolution the daily revolution of all the
other spheres, which are within it; it is, as Beatrice says, “costui,
che tutto quanto rape l’altro universo seco.”[595] Therefore if we
imagine it possible for the motion of this Crystalline Heaven to cease,
what will be the effect on the motions of the other heavens? Obviously
their diurnal movement from east to west will cease, and we shall only
see them revolving, each in its own period, from west to east. There
will be no alternation of day and night, or rather, there will be one
long day of six months, and one long night of the same length, in
any given place all over the earth. In the same way the moon will be
invisible for half the month; and all the planets will be invisible
to us for half their periods; and as Dante believed only the known
hemisphere of Earth to be inhabited, he could say that during one half
of each period no one would see the planet at all. He enumerates the
half period in each case, as follows:—

------------------------------------------------------------------------
[594] _Conv._ II. xv. 132-155.

[595] “That one which sweeps the whole of the rest of the universe
along with it.” _Par._ xxviii. 70, 71.
------------------------------------------------------------------------

                  _Half Period     Whole Period given by Alfraganus_
  “_Planets._”   (_approximate_)        (_El. Ast. ch. xvii._)
                 _given by Dante.    Years  Months  Days_

    Saturn       14½ years           29       5      8
    Jupiter       6      ”           11      10     14½ about.
    Mars         about a year         1      10     22 nearly.
    Sun          182 days, 14 hrs.   ...           365¼ nearly.
                 {about the same
    Venus        { as the sun.       ...                  ”
    Mercury        ”     ”           ...    ...           ”
    Moon         14½ days            ...       (nearly) 27, 7¾ hrs.
                                 (Paris edition, 29 days, 12¾ hrs.)

If we compare these with the zodiacal periods given by Alfraganus,
we see that Dante has taken those of Saturn, Jupiter, and Mars at the
nearest whole number of years and halved them, but with the sun he
seems to have used that more exact value with which we have already
seen that he was acquainted. For to divide the 365¼ days of Alfraganus
by 2 would have given him exactly 182 days 15 hours; but dividing 365
days 5 hours, and neglecting minutes gives 182 days 14 hours. The
large oscillations of Venus and Mercury would make their periods of
visibility very irregular, but the mean period would be, as Dante says,
about the same as that of the sun. He has made a slip with the moon,
for of course it is her sidereal period of 27 days 7¾ hours which he
should have taken, giving a half period of less than 14 days, whereas
he has evidently taken the mean synodic period of 29 days 12¾ hours,
and ignored the hours. All the printed editions of Alfraganus give the
sidereal period in this passage, except the Paris edition of 1546; but
that gives the synodic,[596] so it doubtless appeared on some mediæval
MSS. Dante must have had the misfortune to possess or consult one of
these.

------------------------------------------------------------------------
[596] Toynbee, “Dante’s Obligations to Alfraganus in _Vita Nuova_ and
_Convivio_,” in _Romania_ xxiv. 95.
------------------------------------------------------------------------

As for the stars, one third of their sphere would not yet have been
seen. This is not difficult to understand if we remember what the
movement of the star sphere was supposed to be, and how long it was
since man had first begun to look upon it, according to Dante’s
chronology. The movement which makes the equinoctial point shift its
place among the stars was thought to be a movement of revolution of
the whole star sphere, and its rate to be one degree in a century;
the age of the world, we learn from _Par._ xxvi. 118-123, was over
sixty centuries when Dante wrote. For Adam said that he had spent 930
years on Earth and 4302 in the Limbo, so that Dante evidently counted
5232 years from the Creation to the Crucifixion, that is (5232-33 =)
5199 to the beginning of our era at the birth of Christ, which is the
date given by Orosius; adding 1300 years to this, we find that the age
of the world in Dante’s day was more than 6000 years. Therefore the
star sphere had revolved, since the beginning of the world, through
more than 60 degrees.

The first inhabitants of this earth saw half the starry sky or 180°,
and since then it had revolved through 60°, which together is equal
to 240°; therefore there would still remain 120°, or one third of a
revolution, to be made to complete the whole 360°, and bring every
part of the star sphere into view. Just before this passage Dante
had expressed the same idea in another way. This movement proper to
the star sphere, he says, will never have an end, for the end of
a revolution is to return to the same point; and this heaven will
never do so, for since the beginning of the world it has turned
through a little more than the sixth part of its whole revolution
(60° = ⅛ of 360°), and we are already in the last age of the world, and
indeed are awaiting the consummation of the celestial motion.[597]

------------------------------------------------------------------------
[597] _Conv._ II. xv. 108-118.
------------------------------------------------------------------------

If the premises be granted, the conclusions are correct. As regards
sun, moon, and planets, they are correct even from the point of view of
modern knowledge. For if the diurnal motion (that is Earth’s rotation)
were to cease, while her other motions, and those of the rest of the
solar system remained as at present, her motion round the sun would
cause it to rise and set once in a year, and the appearance of moon and
planets also would be as described. The vastly distant stars would have
no appreciable motion, save that caused by precession, for if the earth
revolved round the sun without turning on her axis, the same stars
would always remain on the meridian at any given place. Precession,
however, would not have the result which Dante supposed. He considered
it to be a rotation of the star sphere, but we know that it is merely
a nodding. Hence at any given place a star at the pole would describe,
in the course of centuries, a small circle in the sky, and those at the
equator would move in short lines first north and then south, while
stars between would move in ellipses which become narrower as they
approach the equator. All round the horizon, therefore, there would be
slight very slow changes, bringing a few fresh stars into view, and
causing others to disappear. The whole amount of the sky actually seen
would vary but little, even if the world should last much longer than
Dante expected.

Dante evidently took his value of precession from Alfraganus, for he
was one of the few Arab astronomers who accepted Ptolemy’s erroneous
figure.

In the _Paradiso_, as the poet mounts with Beatrice from sphere to
sphere he mentions the number of each one in its order. The moon is “la
prima stella,”[598] Mercury “il secondo regno,”[599] Venus “il terzo
ciel,”[600] the spirits met in the sun are “la quarta famiglia,”[601]
Mars is “questa quinta soglia,”[602] and “più levato”[603] than
the last heaven, Jupiter is the “stella sesta,”[604] Saturn “il
settimo splendore.”[605] The starry heaven is alluded to as “la spera
ottava.”[606] The Primum Mobile is “il ciel velocissimo,”[607] “il
maggior corpo.”[608] The Empyrean, “il ciel ch’ è pura luce,”[609] is
called “l’ultima spera,”[610] but this has no limits and no movement,
and therefore no poles:—

------------------------------------------------------------------------
[598] “The first star.” _Par._ ii. 30.

[599] “The second realm.” _Par._ v. 93.

[600] “The third heaven.” _Par._ viii. 37.

[601] “The fourth family.” _Par._ x. 49.

[602] “The fifth threshold.” _Par._ xviii. 28.

[603] “More lofty.” _Par._ xiv. 85.

[604] “Sixth star.” _Par._ xviii. 68, 69.

[605] “The seventh splendour.” _Par._ xxi. 13.

[606] “The eighth sphere.” _Par._ ii. 64.

[607] “The swiftest heaven.” _Par._ xxvii. 99.

[608] “The greatest body.” _Par._ xxx. 39. Compare _V. N._ xlii. 47.
“Oltre la spera che più larga gira,” (“beyond the sphere which has the
largest circle).”

[609] “The heaven of pure light.” _Par._ xxx. 39.

[610] “The last sphere.” _Par._ xxii. 62.

            “ ... In quella sola
    E ogni parte là dove sempr’ era;
    Perchè non è in loco, e non s’impola.”[611]

[611]
              “ ... Within that one alone
    Is every part where it has always been;
    For it is not in space, nor turns on poles.”
               _Par._ xxii. 65-67. (_Longfellow._)
------------------------------------------------------------------------

In _Conv._ II. iv. 35-39 it is thus described:—

    “Questo è il sovrano edificio del mondo, nel quale
    tutto il mondo s’inchiude; e di fuori dal quale
    nulla è; ed esso non è in luogo, ma formato fu
    solo nella Prima Mente, la quale li Greci dicono
    Protonoe.”[612]

------------------------------------------------------------------------
[612] “This is the sovereign edifice of the world, in which all the
world is enclosed, and beyond which is naught; and it exists not in
space, but received form only in the Primal Mind, which the Greeks call
Protonoe.” See also _Ep._ x. 442-447.
------------------------------------------------------------------------

We must remember, however, that the spheres are sometimes counted in
the other direction, from the outermost to the innermost or lowest, and
therefore this “ultima spera”[613] is elsewhere spoken of as “il primo
cielo,”[614] “il primo giro,”[615] “cœlum primum.”[616]

------------------------------------------------------------------------
[613] “Last sphere.”

[614] “The first heaven.” _Purg._ xxx. 1.

[615] “The first circle.” _Par._ iv. 34.

[616] “First heaven.” _Qu._ iv. 7.
------------------------------------------------------------------------


2. THE SPHERES AND THE FOUR ELEMENTS.

The pure region of the spheres, “il paese sincero,” is immortal as the
spirits themselves;[617] but below the lowest celestial sphere (“la
celestial c’ha men salita” _Par._ iv. 39) all is mortal and transitory,
as the Greeks and the Latin poets had said. This is expressed in the
Letter to Can Grande, when Dante contrasts the spheres (cœlum) and the
elements, and says: “illud incorruptibile, illa vero corruptibilia
sunt.”[618] It is also implied in Virgil’s address to Beatrice:

------------------------------------------------------------------------
[617] _Par._ vii. 130-132 compared with 67, 68. See also _Par._ i. 64
and 76.

[618] _Ep._ x. 435-437.
------------------------------------------------------------------------

    “O donna di virtù, sola per cui
     L’umana specie eccede ogni contento
     Da quel ciel che ha minor’ li cerchi sui.”[619]

------------------------------------------------------------------------
[619]
    “O Lady of Virtue, thou alone through whom
     The human race exceedeth all contained
     Within the heaven that has the lesser circles.”
     _Inf._ ii. 76-78. (_Longfellow_).
------------------------------------------------------------------------

It is only through the spiritual teaching which Beatrice symbolizes
that the human race can rise above all that is comprised within the
heaven of the smallest sphere. And it is taught by Beatrice herself
when, in the heaven of Mercury, she discourses on the mysteries of the
creation and redemption. The angels, the souls of men, and the spheres,
were created directly by God, she says, and are therefore immortal,
but the elements, water, fire, air, earth, and all things that are
formed out of them, also the souls or living principles of all animals
and plants, were created through intermediate instruments and are
mortal. These intermediate instruments are the heavenly bodies. Pure
or inchoate matter was created at the beginning by God, and a power
infused into the stars to give it form.[620]

------------------------------------------------------------------------
[620] _Par._ vii. 124-143. Compare with Plato’s account of the creation
of living beings (Part I., _Plato_).
------------------------------------------------------------------------

Dante follows the classics and agrees with his contemporaries in
arranging the four elements in four spheres, which are below the
celestial spheres. The sphere of Fire is immediately within that of the
moon, below this comes Air, then Water, and lastly the solid sphere of
Earth. The contrast between Fire which constantly tends to rise towards
the moon, and Earth which sinks towards the centre of the universe, is
a favourite thought with him;[621] and lightning striking the earth
is described as fleeing its proper place.[622] Aristotle seems to
have regarded the four elements as flowing into one another, so that
these lowly spheres beneath the moon were not sharply divided, but his
mediæval disciples, following the Greek idea to its logical conclusion,
conceived them with boundaries as definite as those of the celestial
spheres. “Exhalations” could pass from one to another, but each
particle of every element tended always to revert to its own place,
which was distinct from the others.

------------------------------------------------------------------------
[621] _Par._ i. 115, 117; _De Mon._ I. xv. 38-41; and III. vii. 30, 31,
etc.

[622] _Par._ i. 92, 130-134.
------------------------------------------------------------------------

And here they encountered a serious difficulty. If the sphere of water
is naturally higher than that of earth, how comes it that in one
quarter of the globe land rises above the ocean? It was recognised as
necessary that this should happen in some part of the world, in order
for an opportunity to be given for the elements to combine and to form
all those substances and all those living creatures, including man, for
which this earth was prepared; it was also agreed that the celestial
spheres were the agency by which the Creator had first chosen to “let
the dry land appear,” and by which it was maintained above the ocean;
but the exact nature of this force and the way in which it acted was a
question sometimes discussed. Albertus Magnus was of opinion that the
rays of the sun and the stars, which had more power in the temperate
and tropic zones than in the arctic, had here dried up the ocean, and
he quotes Albumassar’s statement that this proves the existence of land
on the southern side of the equator also. Ristoro, on the other hand,
believed that the waters had been drawn up and rolled back from the
habitable earth, and he attributes the elevating force to the stars of
the north, bringing in his favourite theory that in this hemisphere
they are far more numerous, and the constellations, from their upright
position, are far more powerful than in the south.

He compares this lifting force of the stars to the attractive power
of a magnet over iron, and argues that it must be the waters which
are drawn away from the earth, not the earth which is lifted above
the water, because the starry influence in its downward course would
meet first the sphere of water, and moreover it is lighter and easier
to move than Earth. He also thinks that the presence of springs
on mountain tops is to be explained by the fact that the ocean is
preserved at a higher level, hence water percolating through the porous
land, as through a sponge, is forced up to its utmost height.

It does not seem as if Dante had paid much attention to this problem
when he was writing the _Convivio_, for although he calls the habitable
part of the earth “the uncovered land,” “la terra discoperta” (_Conv._
III. v. 73), he speaks of Earth and ocean as if they formed a globe
together, “Questa terra ... col mare è centro del cielo,”[623] in the
manner of Alfraganus, “Inter sapientes convenit, terram unà cum aqua
globosam esse.”[624] But if we may believe that Dante is the author
of the _Quæstio de Aqua et Terra_—a belief shared by many experts—he
became greatly interested in the problem later on. According to the
introduction and the final colophon, he attended a discussion on the
subject and joined in it himself, when in Mantua, and afterwards in
Verona less than two years before his death he wrote and read in public
a Latin treatise in which his arguments and conclusions are set forth.

------------------------------------------------------------------------
[623] “This earth, together with the sea, is the centre of heaven.”
(_Conv._ III. v. 63-65.)

[624] “It is agreed among learned men that earth and water together
form a globe.” (_El. Ast._ iii.).
------------------------------------------------------------------------

He seems to have had in mind Ristoro’s book, and while refuting some
of the conclusions agrees with others. As a thirteenth century scholar
he admits, as a matter of course, that the centre of the earth is the
centre of the Universe and the goal towards which all heavy things
tend; that earth as the heaviest element ought to be everywhere nearest
this centre, while water ought to occupy the nobler place above it,
that is, nearer to the most noble sphere of all which envelops all the
others (the Empyrean). He also reasons, in true Dantesque and true
mediæval fashion that there must be some place in the universe where
all the elements may meet and mingle so that all potential forms of
matter may be realized; otherwise the Mover of heaven, in whom all
these forms (Plato’s Ideas) actually exist, would fail to give complete
expression to his goodness, which is impossible.[625]

------------------------------------------------------------------------
[625] _Qu._ xviii. 28-54. This may be compared with _Par._ xxix. 13-18.
------------------------------------------------------------------------

The author of the _Quæstio_ denies, however, that this was accomplished
by the removal of part of the sphere of water from the underlying
earth. The ocean cannot have been drawn away and heaped up, he says,
for water would always flow down again, being fluid and naturally
seeking its own level; nor can the sphere of water be eccentric to that
of Earth so that the latter emerges from it in one part. The reason for
this is interesting since it implies a curious and apparently novel
theory of gravity. Aristotle’s theory was that all heavy things tend
by a natural law towards the centre of the universe, and therefore
necessarily range themselves in spheres round it; the writer might
therefore have made short work of Water’s eccentric sphere by stating
briefly that it could not exist; instead of this, however, he suggests
a new law of gravity, apparently invented on the spur of the moment,
according to which everything which has weight tends towards the centre
of its own circumference. If then earth and water had two separate
centres, they would fall naturally in different directions, or as he
puts it “to different _downs_.” Yet we know that the law of gravity
is the same for both, and therefore their spheres must be concentric.
The centre of the universe must be also the centre of the sea.[626] It
had apparently been urged (perhaps in the discussion at Mantua) that
since water follows the moon in the tides, its sphere may also imitate
hers in being eccentric, but although Dante takes for granted that a
connection between moon and tides is proved (and indeed it had been
noted by the Greeks),[627] he replies that imitation in one particular
need not imply imitation in all. Again, if the sphere of earth emerged
from the sphere of water in the way proposed, the outline of the
emergent earth must be circular, instead of which it is that of a
half-moon, or nearly so, its width from east to west being much greater
than its length from north to south.

------------------------------------------------------------------------
[626] _Qu._ xv. 10, 11.

[627] See p. 134.
------------------------------------------------------------------------

Dante has been blamed for assigning this shape to the emergent earth,
but the comparison of Earth’s habitable quadrant with the illuminated
quadrant of the moon is perfectly just, as we saw with Ristoro,[628]
from whom Dante is perhaps quoting here. The qualifying “vel
quasi”[629] is added because the truly habitable regions did not extend
over the whole quadrant, but stopped short at the arctic circle.

------------------------------------------------------------------------
[628] See p. 247.

[629] “Or nearly.” _Qu._ xix. 61-63.
------------------------------------------------------------------------

The existence of springs on mountain tops is explained by the fact
that water rises thither not in the form of water but of vapour.
Another upholder of Ristoro’s theory that Water was rolled away from
Earth seems to have brought forward as evidence that sailors can see
distant land from the mast which is invisible from the deck, and that
therefore it evidently lies below the ocean; but this is confuted by
the true and well known explanation that it is the convex shape of
the sea which hides the distant land. Our author adds to his other
arguments, in the curiously casual way so characteristic of his age,
the ordinary observation which would be the first to occur to us, and
quite sufficient in itself, viz. that instead of seeing a great wall of
ocean rising above our sea-coasts, we invariably see the coast rising
above the sea.

His own idea is that though the sphere of Water in general rises above
Earth, in one part of the northern hemisphere Earth has been drawn up
above the ocean. Earth must be subject to an uplifting influence, as
well as to the downward drag of gravity, just as man is susceptible to
the influence of reason as well as to the sway of his lower passions.
This uplifting influence is not inherent in Earth herself, an upward
impulse would be contrary to her own nature; nor can it be in water, or
air, or fire, since all these are homogeneous bodies, and their virtue
is evenly distributed, so that they could not cause a local and partial
effect. It must be therefore in one of the heavens, and it remains for
us to enquire which.

It cannot be in the heaven of the moon, for in the moon herself resides
whatever influence comes from her sphere;[630] and she goes as far
south of the equator as she does north: therefore she would raise land
beyond the equator as well as on this side, but this is not so.

------------------------------------------------------------------------
[630] Compare with _Conv._ II. vii. 88-100, where the poet says that
the influence from each sphere comes on the rays of the planet in that
sphere, also _De Mon._ III. iv. 139, 140.
------------------------------------------------------------------------

Then follows a passage of which commentators can make nothing as it
stands:—

    “Nec valet dicere quod illa declinatio non
    potuit esse propter magis appropinquare terræ
    per excentricitatem; quia si hæc virtus elevandi
    fuisset in luna, (quum agentia propinquiora
    virtuosius operentur) magis elevasset ibi quam hic.”[631]

------------------------------------------------------------------------
[631] “Nor does it avail anything to say that that declination could
not take place because of approaching nearer the earth through
eccentricity; for if this elevating virtue were in the moon, since
agents act the more powerfully the nearer they are, she would elevate
there rather than here.” _Qu._ xx. 65-71.
------------------------------------------------------------------------

Mr. Wicksteed suggests reading “elevatio” instead of “declinatio,” and
apparently deletes the “non,”[632] and Dr. Moore seems to read the same
way,[633] for both agree in interpreting as follows:—the author is
stating an argument that the elevation of land (in only one hemisphere)
might be due to the moon’s coming nearer to Earth in one part of her
orbit, owing to its eccentricity; to which he replies that if that were
the cause the elevation would be greater in the south than here in the
north, because the moon is nearer to the earth when she goes south.

------------------------------------------------------------------------
[632] Note on this passage in “Temple” Dante.

[633] _Studies in Dante_, ii. p. 339.
------------------------------------------------------------------------

This is supposed to imply a belief that the moon is always in
perigee[634] when south of the equator, whereas the fact that her
perigee revolves all round the zodiac was as well known to Ptolemy and
Alfraganus as it is to modern astronomers. The interpretation therefore
convicts the author of the _Quæstio_ of so serious and inexplicable a
blunder that these commentators find themselves obliged to consider
it as evidence either that it was not written by Dante, or that his
knowledge of astronomy was much less extensive than has been supposed.
It is suggested that there may have been a popular fallacy in his time
that the moon was like the sun in this respect—although to know that
the sun has a perigee, and that it is situated in the south, requires
some acquaintance with astronomy! However, Dr. Moore has searched
Alfraganus and other works in vain to find a suggestion of this kind.

------------------------------------------------------------------------
[634] Nearest Earth.
------------------------------------------------------------------------

[Illustration: Fig. 52. The moon’s epicycle and deferent.

(The dotted line represents the southern half of the deferent).]

Yet an explanation and a source of this statement is not far to seek,
and instead of proving ignorance it indicates that the author of the
_Quæstio_ knew his Alfraganus well. The passage is evidently slightly
corrupt, but the clue to its meaning lies in the word “eccentricity.”
In two other places of the _Quæstio_ the moon’s eccentric “orbis”
is alluded to,[635] but if we translate this as “orbit” we shall
be introducing modern ideas which meant nothing to Dante or his
contemporaries. According to Alfraganus and Ptolemy the moon’s orb
or sphere[636] was eccentric, but this was not the main cause of her
varying distance from Earth. It was the revolution of her epicycle
round its centre C, which caused her to move continually from apogee M
to perigee P; and as the whole epicycle was meanwhile revolving on the
deferent round C, and these two periods were not quite equal, the moon
was as often in the perigee of her epicycle when it was south as when
it was north. But besides this, the deferent, being eccentric to Earth,
had also a perigee and apogee; and Alfraganus says that _the perigee
of the eccentric is always in the south_. “Saturnus, Jupiter, atque
Mars eccentricorum suorum absidas summas et imas habent declinatas a
zodiaco, illas ad boream, hasce ad austrum, secundum eandem semper
deflexus mensuram: _quedadmodum res in Luna obtinet_.”[637]

------------------------------------------------------------------------
[635] _Qu._ vii. 4, 6, and xxiii. 52.

[636] “Orbis” and “sphæra” are used indifferently by Alfraganus to
indicate the celestial spheres: thus, in ch. xii. he says “_Orbes_, qui
stellarum omnes motus complectantur, numero esse octo,” and on the next
page, “unamquamque harum _sphærarum_ octo.”

[637] “The upper and lower apsides of the eccentrics of Saturn,
Jupiter, and Mars, have a certain declination from the zodiac, the
former to the north, the latter to the south, the amount always
remaining constant: _and it is just the same with the moon_.” _El.
Ast._ xviii. par. 6.
------------------------------------------------------------------------

The upper and lower apsides are defined in chapter xii. as the
positions of apogee and perigee respectively.[638]

In this quotation the word “declinatas” also supplies us with the
meaning of Dante’s “declinatio,” which need not be changed for
“elevatio.” He is using it in the astronomical sense of position north
or south, like Alfraganus and modern astronomers, and it refers here
to the “declinet” of five lines earlier. “Luna ... tantum _declinet_
per zodiacum ab æquinoctiali _versus polum antarcticum_ quantum versus
arcticum.”[639]

------------------------------------------------------------------------
[638] In the edition of Golius ch. vii. par. 5, the position of
greatest distance is called the perigee, of least the apogee, but this
mistake is corrected in the next paragraph.

[639] “The moon’s declination in the zodiac from the equator towards
the south pole is as great as towards the north.” _Qu._ xx. 61-63.
------------------------------------------------------------------------

It is only necessary to delete “quod” and “non potuit,” and the
whole passage becomes clear and, from the point of view of mediæval
astronomy, correct. The author has shown that the moon cannot be
supposed to exert any preponderating influence in the northern
hemisphere, because her declination south is equal to that in the
north. Nor is it of any use, he adds, to say that this declination
(south) results from her approaching the earth more nearly on her
eccentric orb (see diagram);[640] for (although this does imply an
unequal influence) if the elevating influence came from the moon, it
would act more powerfully in the south than here in the north, since
the nearer an agent is the more powerfully it acts.

He goes on to say that the same reasoning rules out the planetary
spheres, and here Alfraganus still supports him, for Saturn, Jupiter,
and Mars are said to have the perigees of their eccentrics in the
south, just like the moon, while those of Venus and Mercury are
continually changing.[641]

------------------------------------------------------------------------
[640] The deferent was the equator of her orb or sphere.

[641] Ristoro also defines apogee and perigee (“auge” and “opposito
d’auge”) as effects of movements on an epicycle, and says that the
deferent is “declined” from the ecliptic (“declinato della via del
sole,”) part being north and part south, but he does not say whether
its perigee is north or south. _Comp. del Mondo._ I. xii. xiv., and
III. vii.
------------------------------------------------------------------------

As for the Primum Mobile, or ninth sphere, it is uniform throughout,
and consequently quite uniform in virtue, therefore there is no reason
why it should elevate land here rather than elsewhere. Since, then,
there are no more moving bodies except the star sphere, or eighth
heaven, it must be from this that the lifting power proceeds. And it
is specially adapted to exercise such an influence since it contains
a number of stars, all of which have different “virtues.” Without
repeating Ristoro’s naïve assertions about the greater number and the
upright positions of the northern constellations, our author bids us
remark that star differs from star, constellation from constellation,
and that their influences are also diverse, so that those in the north
have different virtues from those in the south. The lifting virtue
which raises the land must reside in those stars which are between
the equator and 67° north, since those are above the habitable earth;
but we do not know the nature of the force they exercise, whether
it attracts the land as a magnet attracts iron, or forces it up by
generating underground vapours, such as have raised some mountains
(Aristotle had said in his _Meteorologica_ that volcanic hills were
formed by pent-up winds beneath them).

After so elaborate a search for a power capable of raising land only
in the north and not in the south, we naturally inquire why in the
east and not in the west? But to this we only receive the reply that
there was not enough material to go round, and that we must not ask
presumptuous questions. Let us seek to approach divine and immortal
things as nearly as is possible to human nature, but leave those which
are too high for us.

This somewhat lengthy description of the contents of the _Quæstio_ has
been given because, even if it is not Dante’s work, it illustrates
well the current ideas concerning the Cosmos, its form and forces. So
many of the ideas, however, and even the expressions find parallels in
the unquestioned writings of Dante, that the internal evidence for its
genuineness is strong.[642]

------------------------------------------------------------------------
[642] For a thorough discussion of this question see Moore’s _Studies
in Dante_ ii. pp. 303-374.
------------------------------------------------------------------------

In his poems Dante is faithful to his own descriptions of the universe
in prose, and in the visionary journey of the _Divine Comedy_ he
passes successively through all the spheres which are enumerated in
the _Convivio_ and the _Quæstio_. The central sphere of earth, the
lowest of all the elements, “il suggetto dei vostri elementi,”[643]
is completely traversed, from side to side, and on the further side
is seen the vast sphere of ocean which envelopes three-quarters of
the earth. The Mountain which the poet has placed here (his only
innovation) rises out of the water towards the heavens higher than any
other, “inverso il ciel più alto si dislaga,”[644] and in climbing
it he reaches that region in the sphere of air into which no cold
exhalations can rise from earth or sea, neither the “secco vapor”[645]
which causes wind and earthquake, nor the “esalazion dell’ aqua”[646]
from which are formed rain and hail, cloud and dew. Hot exhalations
ascend to the sphere of fire, there to become meteors or comets (see
p. 103); but the cold vapours rising as high as they can towards the
sun which draws them up (“retro il calor”[647]), are unable to ascend
beyond the Gate of Purgatory.[648] Therefore Purgatory is exempt from
all changes except those caused by that which heaven receives from
itself into itself. This was ingeniously conjectured by Venturi to be
light, since there is change of day and night in Purgatory; but from
the context it seems clear that human souls are meant. Souls come forth
from their Creator, whose special abode is the heaven of heavens,
and return thither after purification. And it was the rising of the
purified soul of Statius, ready to return to heaven, which had been the
cause of that trembling of the Mountain of which he is here speaking.

------------------------------------------------------------------------
[643] “The foundation of your elements.” _Par._ xxix. 51.

[644] “Rises highest towards heaven out of the sea.” _Purg._ iii. 15.

[645] “Dry vapour.”

[646] “Exhalations from the water.”

[647] “Behind [_i.e._ following] the heat.”

[648] _Purg._ xxviii. 97-99 and xxi. 52-53. The gate is meant by “i tre
gradi” (“the three steps”), and “ove si serra” (“where it is locked”).
See _Purg._ ix. 76, 106-108.
------------------------------------------------------------------------

After learning this, Dante is surprised to find, on the summit of the
Mountain, that his brows are caressed by a gentle breeze which comes
from the east and bends all the trees of the Forest in one direction.
Matilda tells him that it is true no atmospheric changes are felt on
this Mountain, and it was for this that it was made to rise so high, so
that man in the Garden of Eden, on the top of the Mountain, should be
untroubled by the disturbances which occur lower down: what he feels
now is no fluctuating wind. On this lofty mountain, remote from any
other land in the midst of the hemisphere of sea, he feels for the
first time the revolution of the atmosphere uninterruptedly following
the movement of the celestial spheres.

The idea that Eden was on a lofty mountain, secure from stormy weather,
and inaccessible to fallen man, was a familiar one with mediæval
writers: it was sometimes located on Adam’s Peak in Ceylon, and Bede
thought it might rise as high as the moon, but Albertus Magnus says
this was only meant figuratively. But the connection with Purgatory,
and the thought that here the movement of the heavens might be felt as
a soft breeze, is, so far as I know, all Dante’s own.

In all the _Divine Comedy_ there is no more beautiful allegory than
this. Man in the age of innocence, man to-day when purified from sin,
is already partly in heaven, though he still walks the earth. And like
many another allegory of Dante’s, it follows naturally from the science
of his day. Aristotle had said that the upper air “flows in a circle,
because it is drawn along with the circulation of the Whole,” and
Aquinas:—

    “Thus the air which exceeds the greatest altitude
    of the mountains flows round, but the air which is
    contained within the altitude of the mountains is
    impeded from this flow by the immoveable parts of
    Earth.”

_Purg._ xxviii. 103-108 is almost a poetical paraphrase of this:—

            “ ... In circuito tutto quanto
      L’aer si volge con la prima volta,
      Se non gli è rotto il cerchio d’alcun canto:
    In questa altezza, che tutta è disciolta
      Nell’ aer vivo, tal moto percote
      E fa sonar la selva, perch ’è folto.”[649]

------------------------------------------------------------------------
[649]
            “ ... The universal atmosphere
      Turns in a circuit with the primal motion,
      Unless the circle is broken on some side:
    Upon this height, that all is disengaged
      In living ether, doth this motion strike,
      And make the forest sound, for it is dense.”
                             (_Longfellow_).
------------------------------------------------------------------------

The whole body of the air, everywhere in the world, is turning with the
First Revolution (the Primum Mobile), wherever it is not interrupted by
any obstruction (of hills etc.); and as at this height the Mountain is
altogether free and open to the pure air, this motion strikes the thick
forest and makes it murmur.[650]

------------------------------------------------------------------------
[650] Scartazzini takes the passage as referring to Eden only, and
interprets that all the air _here_ is moving evenly and noiselessly
unless it meets with any obstacle _such as this forest_, when a
murmuring sound results.
------------------------------------------------------------------------

From this region of pure air, Dante rises with Beatrice through the
sphere of Fire, into which already in a dream he had been rapt, on the
first night in Purgatory, by the Eagle with golden feathers, when the
burning heat of the dream-fire roused him from his sleep.[651] Now he
feels no heat, but is amazed at the vast extent of light, greater than
any river or lake ever seen on earth, and at the same moment he begins
to hear the music of the eternal spheres,[652] for he is approaching
the heaven of the moon.

In each one he hears it until the seventh is reached, but here, in pity
for his mortal senses, which are not yet strong enough to bear so much
divine beauty, not only does Beatrice forbear to smile, but the sweet
symphonies of heaven are silent.[653]

------------------------------------------------------------------------
[651] _Purg._ ix. 30-33.

[652] _Par._ i. 76-81.

[653] _Par._ xxi. 58-63.
------------------------------------------------------------------------

Did Dante then, in spite of Aristotle, believe in the music of the
spheres? Perhaps the fact that only the _Commedia_, of all his works,
makes mention of it indicates that he only thought of it as a poetical
fiction, an allegory? Yet it was fully believed in by many in his day,
although opinions varied greatly as to what note each planet sang. The
favourite idea among Greek and Latin writers seems to have been that
the notes made up a musical scale, the lowest sphere sounding forth the
lowest note, and the star sphere its octave; but others thought that
only the seven planets took part in the harmony, corresponding with the
seven strings of the lyre: the moon being at the shortest distance from
Earth, was the shortest string and gave the highest note, Saturn was
the longest and gave the deepest.

Our own Milton, when he prays, “Ring out, ye crystal spheres,” bids the
Primum Mobile join in, as well as the star sphere:

    “And with your nine-fold harmony
    Make up full concert to the angelic symphony.”[654]

And Shakespear lets every separate star swell the chorus:

    “There’s not the smallest orb which thou beholdest
    But in his motion like an angel sings,
    Still quiring to the young-eyed cherubins.”[655]

In the same spirit, but more literally perhaps than these, are we to
understand the music of Dante’s spheres, which accompanies the singing
of the angels:—

        “Il cantar di quei che notan sempre
    Dietro alle note degli eterni giri.”[656]

------------------------------------------------------------------------
[654] _Hymn on the Nativity._

[655] _Merchant of Venice._

[656]
        “The song of those who sing for ever
    After the music of the eternal spheres.”
                  _Purg._ xxx. 92, 93. (_Longfellow_).
------------------------------------------------------------------------


3. DIMENSIONS AND PHYSICAL NATURE OF THE UNIVERSE.

We have seen that Dante believed the circling of the nine moving
spheres and their epicycles to be the immediate cause of the movements
which he saw in stars and planets. If we ask what were his ideas with
regard to their sizes and distances the question is easily answered.

It is a curious fact that although our ideas about the size of anything
we see depend upon the distance at which it appears to be, and no
one can say how far away the sun looks, most of us nevertheless have
a quite definite idea as to how large it looks, about the size of a
dinner-plate, a cart-wheel, &c. Cleomedes, in the days of Augustus,
quotes Lucretius and the Epicureans as believing that the sun is no
larger than it looks, _that is a foot in diameter_; and he rightly
remarks, amongst other arguments to the contrary, that if it were
only that size it would be invisible unless nearer than the tops of
the mountains, yet we see islands and hills projected against it when
rising, which shows that its distance is greater. Dante twice quotes
the same fallacy, as an instance of the folly of trusting to the
impression of our senses, when not corrected by reason, and he tells us
what he believes the true size of the sun to be.

In _Conv._ IV.[657] he says:—

    “Thus we know that to most people the sun appears
    to be a foot wide in diameter; and this is so
    utterly false that according to the investigation
    and discovery made by human reason with her
    attendant arts, the diameter of the sun’s body is
    five times that of the earth’s, and a half besides.
    For whereas the earth has a diameter of six
    thousand five hundred miles, the diameter of the
    sun, which when measured by sense-impressions seems
    to be a foot in extent, is thirty-five thousand,
    seven hundred and fifty miles.”
                        (See also _Ep._ x. 42-46).

When speaking of the planet Venus he says she is “far off from
us, being distant even when she is nearest to us one hundred and
sixty-seven times the distance of the distance of the centre of
the earth from us, which is three thousand two hundred and fifty
miles.”[658]

------------------------------------------------------------------------
[657] _Conv._ IV. viii. 51-64.

[658] _Conv._ II. vii. 104-108.
------------------------------------------------------------------------

Mercury is spoken of in the _Paradiso_ as a small star, “Questa
picciola stella,”[659] and in _Conv._ II.[660] Dante says:—“Mercury is
the smallest star in the sky; for the length of its diameter is not
more than 232 miles, according to Alfraganus, who says that it is one
twenty-eighth of the diameter of the earth,[661] which is six thousand
five hundred miles.”

------------------------------------------------------------------------
[659] “This small star.” _Par._ vi. 112.

[660] _Conv._ II. xiv. 92-98.

[661] The Frankfort printed edition and some Latin MSS of Alfraganus
agree with this: the edition of Golius gives ¹/₁₈.
------------------------------------------------------------------------

It is only in the last passage that our poet quotes his authority,
but in the others also the diameter or the semi-diameter of the earth
is used as the unit of measure, and it is the same as that given by
Alfraganus; so are the sizes of Mercury and the Sun, and the least
distance of Venus is the value given by Alfraganus for the greatest
distance of Mercury, which he asserted to be equal. It seems quite
clear, therefore, that the figures given in the tables on pp. 189-90
represent Dante’s belief as to the dimensions of the Universe. These
passages also are another proof that Dante had not studied Ptolemy’s
own work, for Ptolemy had said that the distances of Venus and Mercury
could not be accurately known.[662]

------------------------------------------------------------------------
[662] _Almagest_, Bk. IX.
------------------------------------------------------------------------

We do not expect exact measures of distance in Dante’s descriptions of
his soaring flight through the spheres, but he so constantly speaks of
the marvellous speed with which he passes from star to star that we
are not required to ignore the stupendous distances between. The one
indication he does give us of the space which separates him from earth
is full of poetry and symbolic meaning: I refer to Folco’s words in the
heaven of Venus:—

    “Questo cielo, in cui l’ombra s’appunta
    Che il vostro mondo face” ...[663]

------------------------------------------------------------------------
[663]
    “This heaven, where ends the shadowy cone
    Cast by your world.”
                   _Par._ ix. 118, 119. (_Longfellow_).
------------------------------------------------------------------------

This is the last of the three heavens in which Dante has met spirits
whose lives did not reach the perfection of the saints in higher
heavens, but were marred by broken vows, earthly ambition, earthly
love; and here he is reminded that he has not yet soared high enough
to be beyond reach of the cone of shadow thrown by the earth. This is
another allegory resting on what was to the poet an astronomical fact.
For Earth’s shadow was said by Ptolemy and Alfraganus to extend to 268
times the distance of her semi-diameter, and the distance of Venus from
Earth varied, according to Alfraganus, between 167 and 1120 times this
unit, while the next planet, the sun, at his least distance was 1120
units distant (the same as Venus’ greatest). Therefore the spheres of
Venus and the two nearer planets Mercury and the Moon, were all within
reach of Earth’s shadow, but the sun and the rest were far beyond
it.[664] Venus and Mercury themselves never could be actually touched
by the shadow like the moon, however, because they keep too near the
sun for Earth to interpose herself between them and the source of light.

(Though the length of the shadow thrown by Earth is nearly accurate,
see pp. 191-92, the planets are a great deal further than Alfraganus
supposed; for the least distance of Venus is nearly 6000 times Earth’s
semi-diameter, and the least distance of Mercury 12,000).

------------------------------------------------------------------------
[664] Rabbi Abraham ben Chija, in his _Sphæra Mundi_, written about
1100 A.D., says that Earth’s shadow extends as far as the distance of
Mercury, not of Venus (Delambre, _Histoire de l’astronomie ancienne_,
and Dreyer, _Planetary Systems_); but this does not agree with the
figures given by Alfraganus.
------------------------------------------------------------------------

Except for this we have only the passage in the _Paradiso_ already
referred to, where Dante, standing among the stars of Gemini, found
the sphere above him too distant to be seen, but turning his gaze
downwards was able to survey all the planets and the earth at the
centre of the World. He knew very well that at a distance from Earth
20,000 times her own semi-diameter it would be impossible to see her as
a disc,[665] far less to distinguish oceans and continents, hills and
river-mouths. It would in fact be like looking at an object one foot in
diameter at a distance of two miles. But as we have before observed,
his power of vision here was more than human: at every step in this
marvellous journey it had grown clearer and stronger, and in the fourth
heaven he had been able to look on spirits which shone in the sun more
brilliantly than the sun itself, although on earth no eye can look upon
the sun.[666]

In the Empyrean, distinctions of space, and impediments to vision
vanished altogether.[667]

------------------------------------------------------------------------
[665] Her diameter would look no larger than the diameter of Saturn,
as we see it when nearest to him; but like Saturn she would be visible
as a bright point, because shining by reflected sunlight. Ancient and
mediæval astronomers never realized this, however, but thought of Earth
as a dark body, receiving light but giving none.

[666] _Conv._ II. xiv. 126, 127; _Par._ x. 40-42, 48.

[667] _Par._ xxii. 67; xxxi. 19-24; xxx. 118-123.
------------------------------------------------------------------------

With regard to the physical nature of the heavenly bodies, Dante and
his contemporaries had no means whatever of investigation, and could
only profess ignorance or accept one or other of the guesses of their
predecessors. Some of the Greek philosophers, as we saw, guessed
that the planets were worlds somewhat like the earth, others thought
they were composed of fire or of air. But the general belief in the
thirteenth century was that planets and spheres alike were composed
of a kind of celestial matter, called by Aristotle and the Greeks
“æther,” by the Arabs “al-acir,” an immortal substance which had neither
heaviness nor lightness, and was altogether distinct from any of the
four elements existing below the sphere of the moon. Beatrice speaks of
“this sphered ether,” “questo etera tondo.” _Par._ xxii. 132.

Dante’s description of this celestial substance when he first enters
the ethereal world is one of the finest instances of his faithfulness
to the teachings of astronomy as he had learned it, combined with
poetical imagination, and at the same time his power of using material
facts (as he conceived them) to present an allegory of the deepest
religious mysteries. If we merely listen to the magic of the words,
an impression is conveyed of something mysteriously beautiful and
dazzling, unlike anything known on earth; but if we look into the
meaning, we find that the globe of the moon has just those strange,
contrasting qualities, just the colour and the form which a sphere of
ether may be imagined to have. It is white and rounded like a pearl,
“polished” as Plato said of the universal orb, it is thick and shining,
soft as cloud but hard as diamond; and it offers no more resistance to
Dante as he enters into it than does water to a ray of light.[668]

Then follows a discussion concerning the substance not only of the
moon but of all the heavenly bodies. On hearing that he has reached
the boundaries of the immortal world, and has entered “la prima
stella,”[669] Dante eagerly enquires of Beatrice what are those dark
markings in the body of this planet which are seen from Earth and have
given rise to the fable of Cain. She smiles a little, and bids him tell
her first what is his own opinion. He advances the theory which he had
taught in the _Convivio_, viz. that the parts of the moon which look
dark to us are less dense than the rest, and therefore the rays of the
sun when striking them are not stopped and reflected back to us; hence
the brightness is less than in other parts of her surface.

    “L’ombra ch’ è in essa, ... non è altro che rarità
    del suo corpo, alla quale non possono terminare
    i raggi del sole e ripercuotersi così come nell’
    altre parti.”[670]

------------------------------------------------------------------------
[668] _Par._ ii. 25-45.

[669] “The first star.”

[670] “The shadow which is in her is nothing but rare parts of her
substance, which cannot stop the rays of the sun and reflect them back
like the other parts.” _Conv._ II. xiv. 72-76.
------------------------------------------------------------------------

This explanation seems to have been first suggested by Averroës, the
Arab philosopher and astronomer of Cordova, who was known in the Middle
Ages as “The Commentator,” from his famous commentary of Aristotle.
The suggestion occurs in his _De Substantia Orbis_, and as it follows
a quotation from Aristotle (to the effect that the moon is more nearly
related to Earth in her nature than to the stars), it was believed by
many to be originally due to Aristotle himself.

The strange circumstance that the moon alone, among all the heavenly
bodies, appeared to have dark shadows on her bright face, had roused
much curiosity already among the Greeks; and Plutarch, in his dialogue
“On the Face in the Moon,” mentions the different explanations
suggested in his day. Some thought that the polished surface of the
moon reflected, like a mirror, parts of the earth; the Stoics said that
air was enclosed within her globe of fire and obscured it in certain
places, but this view was rejected with contumely by Plutarch.

    “It is a slap in the face to the moon when they
    fill her with smuts and blacks, addressing her in
    one breath as Artemis and Athena, and in the very
    same describing a caked compound of murky air and
    charcoal fire, with no kindling or light of its
    own, a nondescript body smoking and charred like
    those thunderbolts which the poets address as
    lightless and sooty!”[671]

------------------------------------------------------------------------
[671] Plutarch, _On the Face in the Moon_, translation by Prickard.
------------------------------------------------------------------------

The third hypothesis, which was favoured by most of the speakers in the
dialogue, was that the moon was not a star at all, but a kind of more
beautiful Earth; and it was even suggested that men might dwell on her
who thought their world the only place fit for human beings, looking
down with contemptuous pity on our Earth, as a sort of sediment and
slime of the Universe, appearing through damps and mists and clouds, a
place “unlighted, low, motionless,” entirely incapable of supporting
moving breathing warm-blooded animals!

This was not a view which could possibly be held by mediæval
Christians, and in a treatise on Aristotle’s _De Cœlo_, attributed to
Albert of Saxony, we find others put forward. The author disproves
the old theory of a mirror-like moon reflecting parts of Earth, and
also another that the moon draws up cold vapours which are seen like
clouds on her surface, and upon which she is nourished—for how should
an eternal heavenly body need nourishment?—and finally he expounds the
theory of “The Commentator,” with which he agrees. The markings are
rare parts of the moon’s substance, which cannot shine so brightly as
the denser parts, and this varied surface he compares with alabaster,
in which “the dense and not translucent part is very white, while that
which is translucent like glass is obscure and tends to blackness.
And if,” he adds, “it is asked why the moon is thus dissimilar in her
parts, the reply is that this is her nature.”[672]

------------------------------------------------------------------------
[672] See Paget Toynbee, _Le Teorie Dantesche sulle Macchie della
Luna_, in _Giornale Storico della Letteratura Italiana_, vol. xxvi. pp.
156-161.
------------------------------------------------------------------------

This theory was perhaps the most popular one with mediæval scholars,
though there was some difference of opinion as to whether the dense or
the rare parts of the moon were those that showed dark. Ristoro perhaps
alludes to it, in the passage where he speaks of the moon’s markings,
but in a very confused way, and the contrast of “polished” and “rugged”
surface is what he chiefly lays stress upon.

After upholding this theory in the _Convivio_, Dante rejects it in the
_Paradiso_: perhaps because it was more or less bound up with the idea
that the moon was partly of an earthy nature, and this was inconsistent
with the other theory of Aristotle, so popular among classical writers,
that all within and above the sphere of the moon was eternal and
heavenly. He is evidently very anxious to convince us of the falsity
of his old belief, for he is not content with a simple assertion, but
lets Beatrice reason like a learned doctor, using arguments which would
appeal to his readers, drawn now from experiments which might be used
in a school, and now from the accepted astrological beliefs of the day.

First she reminds him that the numerous stars scattered over the
surface of the eighth sphere differ in brightness, like the different
parts of the moon’s surface, but they differ in the quality (colour?)
of their light, as well as the quantity, and we know that there are
essential differences between them, because their “virtues” are
different. It cannot be, therefore, that they differ simply in density
or rarity of their substance.

Then she shows that in no circumstances is the theory of varying
density in different parts of the moon capable of explaining the
observed variety of brightness. For if the parts which look dark are
less dense than others, either they must be so right through the
planet, or there must be an alternation of dense and rare matter in
those parts, like fat and lean in a material body, one behind the other
like pages in a book. (The double metaphor is characteristic of Dante.)
Now if the first be true, the sunlight would shine through the moon
is those parts, during an eclipse;[673] and if the second, the sun’s
rays must penetrate to the lower-lying denser part, and be reflected
thence just as from the dense parts of the moon’s surface. A possible
objection that in that case the reflecting surface would be further
away, and therefore appear fainter, may be disproved by an experiment.
Take two mirrors and place them at an equal distance from you; place
a third between them but further away, face the three mirrors, and
place a light behind you so that it may be reflected from them all: the
distant one will appear smaller, but no less bright than the two near
ones. This reasoning is perfectly sound.

Then follows the explanation for which all this is a preparation. It
involves an exposition of ultimate causes which we need not enter into
here: for the present we need only say that difference of brightness
is not caused by differences of much or little of the same substance.
There are intrinsic differences between star and star, and between
different parts of the moon,[674] but all are manifestations of divine
intelligence; just as the different members and faculties of a human
body are manifestations of a human soul.

------------------------------------------------------------------------
[673] Albert of Saxony notes this objection, but says the rarity is not
sufficiently great to make these parts transparent.

[674] This is in agreement with modern belief. Some parts of the moon’s
surface reflect sunlight less well than others, and therefore look
dark, just as a peaty soil looks darker than limestone.
------------------------------------------------------------------------

The diversity of the celestial matter is also touched upon in the
_Convivio_, where it is said that the epicycle of Venus is “not of
the same essence as that which carries it [the deferent or large
sphere], although it is more nearly of one nature with it than with
the rest.”[675] Differences of colour are indicated in the glowing
masses of the planets, which are entered by Dante and Beatrice.
As with the moon, they do not merely alight upon the surface, but
penetrate the planetary ether. “Quel ch’ era _dentro_ al sol,”[676]
“Nel profondo Marte,”[677] “La temprata stella sesta, che _dentro
a sè_ m’avea ricolto.”[678] Mercury is called a pearl—“la presente
margarita”[679]—while Mars is “questo fuoco,”[680] and the astronomer
poet says he knew the planet by its burning smile, for it seemed to him
even more ruddy than its wont.

------------------------------------------------------------------------
[675] _Conv._ II. iv. 94-96.

[676] “That which was _within_ the sun [_sc._ the spirits].” _Par._ x.
41.

[677] “In the depths of Mars.” _Par._ xiv. 100, 101.

[678] “The temperate sixth star, which _within itself_ had received
me.” _Par._ xviii. 68, 69.

[679] “The present pearl.” _Par._ vi. 127.

[680] “This fire.” _Par._ xvi. 38.

    “Ben m’ accors’ io ch’ io era più levato,
     Per l’affocato riso della stella,
     Che mi parea più roggio che l’usato.”[681]

[681]
    “Well was I ’ware that I was more uplifted
     By the enkindled smiling of the star
     That seemed to me more ruddy than its wont.”
                      _Par._ xiv. 85-87. (_Longfellow_).
------------------------------------------------------------------------

And when, without being conscious of any movement, he found that the
red light shining on Beatrice had turned to purest white, like a blush
fading from a fair face, he knew that the sixth star (Jupiter) had
received him within itself.

    “E quale è il trasmutare in picciol varco
       Di tempo, in bianca donna, quando il volto
       Suo si discarchi di vergogna il carco,
     Tal fu negli occhi miei, quando fui volto,
       Per lo candor della temprata stella
       Sesta, che dentro a sè m’avea ricolto.”[682]

------------------------------------------------------------------------
[682]
    “And such as is the change, in little lapse
       Of time, in a pale woman, when her face
       Is from the load of bashfulness unladen,
     Such was it in mine eyes, when I had turned,
       Caused by the whiteness of the temperate star,
       The sixth, which to itself had gathered me.”
                    _Par._ xviii. 64-69. (_Longfellow_).
------------------------------------------------------------------------

This contrast between the colours of Jupiter and Mars is referred to
more than once. In _Par._ xxvii., the flaming spirit of St. Peter,
flushed with righteous indignation, becomes brilliant as the planet
Jupiter, and red as Mars:—

      “E tal nella sembianza sua divenne,
    Qual diverrebbe Giove, s’egli e Marte
    Fossero augelli, e cambiassersi penne.”[683]

------------------------------------------------------------------------
[683]
              “He in semblance such became
    As Jove might be, if he and Mars were birds,
    And interchanged their plumes.”
                        _Par._ xxvii. 13-15. (_Carey_).
------------------------------------------------------------------------

And when Dante looks down upon the seven planets he sees

        “il temperar di Giove
    Tra il padre e il figlio.”[684]

------------------------------------------------------------------------
[684] “The temperate light of Jove, between his father and his son.”
_Par._ xxii. 145-146.
------------------------------------------------------------------------

To understand which we must turn to the oft-quoted fourteenth chapter
of the second treatise in the _Convivio_. Here we find that Jupiter
“moves between two heavens” which “are antagonistic to its excellent
temperateness, that is to say the heavens of Mars and that of
Saturn,”[685] and Dante quotes Ptolemy as saying that Jupiter is a star
of temperate constitution, between the cold of Saturn and the heat of
Mars.

It seems that these ideas of cold and heat, as applied to the planets,
were taken literally, not merely as poetical descriptions of colour,
nor of astrological significance; for Dante says explicitly in the same
chapter of the _Convivio_ that Mars is hot like fire, that this is the
cause of his colour,[686] and that he dries up and burns things.[687]

------------------------------------------------------------------------
[685] _Conv._ II. xiv. 196-198.

[686] _Cf._ Ristoro, _Comp. del Mondo_, III. iii.

[687] _Conv._ II. xiv. 161-165.
------------------------------------------------------------------------

Similarly he appears to have believed that Saturn and the moon were
literally of a cold nature. “Quel pianeta che conforta il gelo,”[688]
in _Canzone_ xv. is doubtless Saturn; and the chill of the hour before
dawn is described as due not only to loss of heat by the earth but
sometimes also to the influence of the cold moon or of Saturn.[689]

Besides her shadowy markings, the moon had another peculiarity which
distinguished her from all other heavenly bodies, for she was the only
planet then known to vary in apparent size and shape “according to the
way in which the sun looks upon her.”[690] She was therefore a very
dark body, though it was believed that she had some light of her own,
and Dante argues in favour of this that she does not become totally
invisible during an eclipse.[691] This was a very natural conclusion:
it would not readily occur to anyone that the reddish light of the
eclipsed moon is sunlight refracted (_i.e._ bent out of its direct
course) in passing through the earth’s atmosphere.

------------------------------------------------------------------------
[688] “The planet that strengthens the cold.” _Canz._ xv. 7.

[689] _Purg._ xix. 1-3.

[690] _Conv._ II. xiv. 78, 79.

[691] _De Mon._ III. iv. 140-142.
------------------------------------------------------------------------

The sun, although the astrologers made him not very much larger than
the brightest fixed stars and the largest planets, was much brighter
and hotter than any, and it was universally agreed that all obtained
their light from him. Even if, like the Moon, they had some light of
their own, and did not only reflect like mirrors, this inherent light
had originally come from the sun and was but absorbed sunlight.[692]
We meet constantly with this idea in Dante’s works. In one of his Odes
the sun is said to “donar luce alle stelle;”[693] in the _Convivio_ he
says, “Il sole ... di sensibile luce sè prima, e poi tutti i corpi
celestiali ed elementali allumina.”[694] The Morning Star is described
as deriving her beauty from the sun;[695] and after the sun has set he
shines forth again in the light of all the stars.[696]

So also says Brunetto Latini, “Sans faille li solaus est fondemenz de
toutès lumieres et de toute chalor.”

------------------------------------------------------------------------
[692] See quotations from Albertus Magnus and Roger Bacon in Moore’s
_Studies_, iii. p. 45, _note_.

[693] “Bestow light on the stars.” _Canz._ xix. 117.

[694] “The sun illumines first himself and then all celestial and
elemental bodies with visible light.” _Conv._ III. xii. 54-56.

[695] _Par._ xxxii. 107, 108.

[696] _Par._ xx. 1-6; compare xxiii. 28-30.
------------------------------------------------------------------------


4. INFLUENCE OF THE SPHERES ON HUMAN AFFAIRS.

If we are to believe a fifteenth century biographer, we have so far
omitted to mention Dante’s greatest claim to be considered a proficient
in astronomy. “He foretold,” says Filelfo, “many of the calamities
of Florence, the wars of Italy, and other political changes, all of
which would have been impossible without an accurate knowledge of the
movements of the celestial bodies.”

Filelfo was a poet, and his authority for this surprising statement
can be no other than that on which, Dr. Moore says, he mainly depends,
and which seldom or never fails him, “his own most airy and lively
imagination unembarrassed by any references to documents.”[697] The
prophecies of the _Divina Commedia_ are obviously written after the
events, and in no single instance are they supposed to have any
connection with the art of the astrologers. On the contrary, it is
remarkable how very little we find in Dante’s writings about the
fate-predicting and character-reading which passed as the chief part of
astronomy with the large majority of his contemporaries, and played a
considerable part even in the scientific writings of his fellow authors.

------------------------------------------------------------------------
[697] Moore, _Dante and his early Biographers_, p. 95.
------------------------------------------------------------------------

Not that he disbelieved in the art: it would have been almost a miracle
if he had. The astrologers in the fourth Bolgia were punished with
other soothsayers not because they deceived credulous clients, but
because they had desired to look too deeply into the future,[698] which
was impiety. For this reason the learned Michael Scot, the honoured
of Popes, was there, as well as poor Asdente, and Guido Bonatti, and
Aruns who from his solitary cave had watched the stars, and prophesied
the victories of Cæsar over Pompey.[699] This orthodox sentiment that
“judicial astronomy,” was apt to be a snare, and lead to practices
condemned by the Church, may have been one reason for Dante’s avoidance
of it; but we cannot read his works without feeling that it was the
beauty of the skies, and the keen desire to understand the structure of
the universe which inspired him to study astronomy, and that he had no
superstitious fear of the heavenly bodies, no greedy wish to make use
of his knowledge to pry into the future. There is no evidence that he
was acquainted with the details of astrology. The few allusions made
in his works to special effects of certain stars or planets are only
to those most familiarly known, and parallel instances might be found
to many of them in modern poems. With this difference, however, that
to-day they are figures of speech: with Dante they represented facts.
Venus was to him in serious truth “la stella d’amor,”[700] “lo bel
pianeta che ad amar conforta,”[701] and exercised a real power over
Folco[702] and Cunizza,[703] and his own heart.[704] He even tells
us, in serious prose, that it is the planet and not the whole sphere,
which is the source of this influence, and that it is borne to us upon
her rays.[705] So also the moon has a special influence, which is
communicated by her rays.[706]

------------------------------------------------------------------------
[698] _Inf._ xx. 38.

[699] _Inf._ xx. 115-118, 46-51.

[700] “The star of love.” _Canz._ xv. 4.

[701] “The fair planet which incites to love.” _Purg._ i. 19.

[702] _Par._ ix. 94-96.

[703] _Par._ ix. 32, 33.

[704] _Conv._ II. _Canz._ 1-6.

[705] _Conv._ II. vii. 88-100.

[706] _De Mon._ III. iv. 139, 140.
------------------------------------------------------------------------

To the strong star of Mars the noble warlike nature of Can Grande was
partly due;[707] Jupiter is a temperate star, not only in the purity
of his colour, but his influence is felt where justice is worked on
earth.[708] Saturn’s influence is modified when he shines in Leo,[709]
the sun has special powers in Aries,[710] and to his presence in
Gemini at the time of Dante’s birth the poet attributes his literary
gift.[711] In _Inf._ xxvi. 23, he again suggests that his mental powers
may be due to the influence of a good star, and Brunetto Latini bids
him follow his star.[712]

Dante also quotes Albumassar, and Seneca, and the events of his own
day, to show that those fiery vapours, meteorites, portend the death
of kings and the downfall of states, adding that this is because they
are effects of the sovereignty of Mars.[713] This passage explains why
the warrior Malaspina is called a vapour drawn by Mars from Valdimagra,
which in the tempest of battle at Piceno shall suddenly split the
clouds and deal death to the combatants.[714]

------------------------------------------------------------------------
[707] _Par._ xvii. 76-78.

[708] _Par._ xviii. 115-117.

[709] _Par._ xxi. 13-15.

[710] _Par._ i. 40-42; _Canz._ xv. 41.

[711] _Par._ xxii. 112-117. The Ottimo, commenting this passage, says
that Gemini “is the house of Mercury, who signifies, according to the
astrologers, literature, science, and learning. And in this direction
it disposes those who are born when it is in the ascendant, and more
powerfully if the sun is in it.”

[712] _Inf._ xv. 55.

[713] _Conv._ II. xiv. 170-180.

[714] _Inf._ xxiv. 145-150.
------------------------------------------------------------------------

The results of the right disposition of sphere with sphere are spoken
of in _Canz._ xix. 77-79; all the nine were in perfect accord when
Beatrice, herself a nine or miracle of perfection, was to be born;[715]
and every star rained its light and its virtue into her beautiful
eyes.[716] There is also a charming sonnet, in which the poet tells us
how all the seven planets influence his lady.

------------------------------------------------------------------------
[715] _V. N._ xxx. 22-24.

[716] _Ball._ vi. 11, 12.

    “Da quella luce che il suo corso gira
       Sempre al volere dell’ empiree sarte,
       E stando regge tra Saturno e Marte,
       Secondo che l’astrologo ne spira;
     Quella che in me col suo piacere aspira,
       D’essa ritragge signorevol arte:
       E quei che dal ciel quarto non si parte
       Le dà l’effetto della mia desira.
     Ancor quel bel pianeta di Mercuro
       Di sua virtute sua loquela tinge,
       E ’l primo ciel di sè già non l’è duro.
     Colei, che ’l terzo ciel di sè costringe
       Il cor le fa d’ogni eloquenza puro;
       Così di tutti e sette si dipinge.”[717]

[717]
    “From that bright star which moveth on its way
       For ever at the Empyrean’s will,
       And between Mars and Saturn ruleth still,
       E’en as the expert astrologer doth say,
     She who inspires me with her beauty’s ray
       Doth subtle art of sovereignty distil;
       And he whose glory doth the fourth heaven fill
       Gives her the power my longing soul to sway.
     And that fair planet known as Mercury
       Colours her speech with all its virtue rare,
       And the first heaven its boon does not deny.
     She who the third heaven ruleth as her share
       Makes her heart full of utterance pure and free;
       So all the seven to perfect her agree.”
                           _Sonnet_ xxviii. (_Plumptre_).
------------------------------------------------------------------------

In more serious vein is the discourse in _Par._ ii. on the different
virtues of the different stars;[718] and this should be compared
with passages in the _Quæstio_ and the _Convivio_. “Sciendum quod
licet cœlum stellatum habeat unitatem in substantia, habet tamen
multiplicitatem in virtute,”[719] sounds like an echo of the words of
Beatrice:

------------------------------------------------------------------------
[718] _Par._ ii. 64-72, 130 to end.

[719] “It should be borne in mind that although the starry heaven has
unity in substance it nevertheless has multiplicity in virtue.” _Qu._
xxi. 12-14.

    “Così l’intelligenza sua bontate
       Multiplicata per le stelle spiega,
       Girando sè sopra sua unitate.”[720]

[720]
                  “ ... E’en so
    The intellectual efficacy unfolds
    Its goodness multiplied throughout the stars,
    On its own unity revolving still.”
                          _Par._ ii. 136-138. (_Carey_).
------------------------------------------------------------------------

And when comparing Nobility with the star-spangled sky, our author says:

    “Tante sono le sue stelle che nel cielo si
    stendono, che certo non è da maravigliare, se molti
    e diversi frutti fanno nella umana Nobiltà, _tante
    sono le nature e le potenze di quelle, in una
    sotto una semplice sustanza comprese e adunate_,
    nelle quali siccome in diversi rami fruttifica
    diversamente.”[721]

------------------------------------------------------------------------
[721]
    “So many are the stars which spread themselves over
    her sky, that surely we cannot wonder if they make
    many and diverse fruits grow on human nobility, _so
    many are their natures and potencies, concentrated
    and united in one simple substance_; and on them
    as on diverse branches she bears fruit in diverse
    ways.”
          _Conv._ IV. xix. 45-52. (_Jackson_).

     See also _Conv._ IV. xxi. 62-66.
------------------------------------------------------------------------

The author goes on to say in the _Quæstio_ that the many and diverse
stars which we see in the eighth heaven were placed there in order that
it might pour down diverse virtues, and that he who perceives this
not, let him know that he is outside the pale of philosophy.[722] In
another place he tells us that the nearer a star is to the mid-circle
of the star sphere, the greater is its virtue:[723] he no doubt
means, not the celestial equator, but the zodiac (or more exactly the
ecliptic), since this was the mid-circle of the star sphere, parallel
to which its slow revolution of 36,000 years was made. This would
agree with the view of the astrologers, who paid more attention to the
constellations of the zodiac than to any others.

------------------------------------------------------------------------
[722] _Qu._ xxi. 17-19.

[723] _Conv._ II. iv. 75-77.
------------------------------------------------------------------------

But we may search all Dante’s works in vain for any reference to the
“houses” or “aspects” of the planets, or for any information about the
masculine and feminine, mobile and stable, signs. All such things,
which seemed to most writers of his day quite as important as the
periods of the planets or the positions of the signs, he entirely
ignores. Among the circumlocutions by which he describes the signs,
such as “the fair nest of Leda,” or “the sign that follows Taurus,”
we never find “the house of Saturn,” or “the sign in which Mars is
mildest.” Leo is called Mars’ own Lion, probably because the “leo
audax et ferox” of bestiaries agreed with the fiery colour and nature
of Mars:[724] astrologically, his signs were Scorpio and Aries. It is
quite astonishing that among all the characteristics of the planets
and spheres mentioned in _Convivio_ II. chapters xiv. and xv., only
two relate to astrology, namely, the temperate disposition of Jupiter
between the hot Mars and cold Saturn, and the power of Mars to draw up
the hot vapours which become meteors and portend the deaths of kings.
All the rest—the markings and phases of the moon, the small size and
proximity to the sun of Mercury, the beauty of Venus and her appearance
alternately as morning and evening star, the brilliance of the sun and
his capability of giving light to all the stars, the position of the
sphere of Mars midway between those of the other planets, the purity
of Jupiter’s colour, the slow movement and distance of Saturn—all
these are purely astronomical, to use the modern distinction. So also
are the characters of the star sphere—the thousand and twenty-two
visible stars, and the indistinguishable stars of the Galaxy, the pole
we see and the other which remains hidden, the conspicuously swift
diurnal movement and the almost imperceptible secular revolution of
36,000 years. Of the Primum Mobile it is remarked that it controls the
movement of all the rest, and of the Empyrean that it is full of peace.

------------------------------------------------------------------------
[724] But see Tozer’s _English Commentary on Dante’s Divina Commedia_,
note on _Par._ xvi. 37. “In mediæval astrology Mars was one of the
Lords of the Lion.”
------------------------------------------------------------------------

The symbolism of the spheres assigned in Paradise to the different
saints is partly drawn from astrological ideas, for in Venus Dante
meets the lovers, in Mars the warriors, in Jupiter the just rulers. But
those who were not eternally faithful to their vows are in the moon
because she has the lowest sphere,[725] the contemplative saints are
in the highest planet, the theologians who enlightened the faithful
are in the sun, and the ambitious are in the little planet which ever
keeps closest to the sun. The heaven of “many and diverse stars” shows
the poet a host of saints, and the Primum Mobile, which controls the
movement of the other spheres, reveals to him the Angels who direct
them.

It seems, then, that Dante was not interested in technical astrology,
and had never made a study of it; and I think we may adduce this
additional evidence that he had not learned astronomy in a university,
or under Cecco d’Ascoli. It is only necessary to look at the list of
books prescribed at Bologna[726] to feel sure that Dante had not taken
a regular course there. The list, it is true, belongs to a somewhat
later time, but there is no reason to suppose that astrology became of
more importance in the late fourteenth century than at its beginning.

------------------------------------------------------------------------
[725] _Par._ iii. 55-57.

[726] See p. 202.
------------------------------------------------------------------------

Nevertheless, however little Dante may have cared for the details of
astrology, we shall never understand all that the skies meant to him
unless we realize that a general belief in their influence on man was
deeply rooted in his mind. For him it was a tremendous fact, and one
which pervades his writings, that stars and spheres are the instruments
of God’s providence, and are ordained by the First Mover to mould the
destinies of Earth.[727] It is their movements which manifest His
Will;[728] they are the hammers,[729] earth the metal, they are the
seals,[730] and earth the wax.

------------------------------------------------------------------------
[727] _De Mon._ II. ii. 15-18, 25, 26, 36-38; III. ii. 30-32; xvi.
91-101; _Ep._ v. 133-135; _Par._ ii. 121, viii. 97-99.

[728] _Ep._ v. 124, 125.

[729] _Par._ ii. 127, 128.

[730] _Par._ ii. 130-132; xiii. 73-75; viii. 127, 128; i. 41, 42.
Ristoro of Arezzo uses the same expression, _Comp. del Mondo_, Bk. VII.
part I. chapter 2.
------------------------------------------------------------------------

Three times the stars are invoked to bring justice and righteousness
on earth.[731] Through the spheres the elements were evolved out of
the first chaotic matter, and everything on earth took form; all life
and motion is generated by them.[732] Man’s soul is a direct creation
by God, but the moving heavens play an important part in the formation
of his material body, his mental faculties, and his disposition.[733]
Were it not for the action of the spheres, children would be precisely
like their parents, their whole nature being governed by the law of
heredity alone: it is the different influences of the skies that give
them different natures.[734] This, says Beatrice, is perhaps what Plato
meant when he said that souls came from different stars and returned
thither: if his meaning was that the influences of the stars is so
great that to them is due the praise or blame which we distribute to
men, there is some truth in the saying.[735]

------------------------------------------------------------------------
[731] _Purg._ vi. 100; xx. 13, 14; xxxiii. 40-45.

[732] _Par._ vii. 133-141; xiii. 65, 66; _Conv._ III. xv. 159-161; II.
xv. 152-154; IV. xxiii. 50-52.

[733] _Conv._ II. xiv. 28-30; IV. ii. 58-61; _Par._ xxvi. 128, 129.

[734] _Par._ viii. 127-135.

[735] _Par._ iv. 49-60. See also _Ecl._ ii. 16, 17; and _Conv._ IV.
xxi. 17-19, 25-27.
------------------------------------------------------------------------

Some truth only—“alcun vero”; for the stars are not independent
powers, for good or evil, which men are unable to resist. This view is
expressly combated in _Purg._ xvi. 58-84. Dante has asked the spirit
of the courtly Venetian Marco Lombardo why the world is so full of
wickedness now, for some say it is the effect of the heavens, and
others seek an earthly cause. Marco groans at the blindness of men, who
accuse heaven for the results of their own misdeeds: it is true that
the heavens influence our lower natures, our instincts, and desires;
but the soul is free, and can control them. This is in accordance
with the teaching of St. Augustine and Aquinas. In one passage of the
_De Monarchia_, Dante goes even further than this, and asserts that
the influences of the spheres are only good, and that evil results
from imperfections in the material on which these perfect instruments
work.[736]

------------------------------------------------------------------------
[736] _De Mon._ II. ii. 21-23; _Cf. Par._ xiii. 64-78.
------------------------------------------------------------------------

Conceptions such as these give us a new idea of mediæval astrology.
They may be mistaken, but at least they are grand, and not unworthy of
a philosopher and a Christian.


5. THE MOTIVE POWER.

Dante’s ideas regarding the laws and origin of motion in the universe
were derived from Aristotelian metaphysics and Church doctrines. He
believed that there were three kinds of motion proper to three kinds
of bodies: _i.e._ heavy bodies tended towards the centre of the
universe, which is also the centre of the earth; light bodies tended
upwards to the region of fire just below the moon; and bodies of
ethereal substance—the stars, planets, and spheres—moved eternally in
circles round the centre. Thus Beatrice, when speaking of the instinct
implanted in all created things, which bears them through the great
ocean of being each to his destined haven, says:—

    “Questi ne porta il foco inver la luna,
         .    .    .    .    .
     Questi la terra in sè stringe ed aduna.”[737]

------------------------------------------------------------------------
[737] “This carries fire towards the moon, this compresses and binds
Earth together.” _Par._ i. 115, 117. See also _De Mon._ III. vii. 30,
31, and I. xv. 38-41; _Conv._ III. iii. 10-13; _Qu._ xviii. 11, 12, and
many others.
------------------------------------------------------------------------

And Virgil:—

        “Il foco movesi in altura,
    Per la sua forma, ch’ è nata a salire
    Là dove più in sua materia dura.”[738]

------------------------------------------------------------------------
[738]
          “The fire doth upward move
    By its own form, which to ascend is born,
    Where longest in its matter it endures.”
    _Purg._ xviii. 28-30. (_Longfellow_).
------------------------------------------------------------------------

That is to say the form of a flame fits it to rise to that place
where, being in its own element, it may last longer than on Earth.
Conversely, the centre of the earth is described as the bottom
of the whole universe, and the point towards which all weights
are attracted.[739] These opposite forces Dante calls gravity and
levity.[740]

------------------------------------------------------------------------
[739] _Inf._ xxxii. 8, and 74; xxxiv. 110, 111. See also _Par._ xxxiii.
22, 23; _Inf._ ix. 28, 29; _Qu._ iii. 6-9, etc.

[740] _De Mon._ I. xv. 46-48; _Qu._ xii. 39-42.
------------------------------------------------------------------------

The most interesting illustration of this force of gravity is the
description, in the last canto of the Inferno, of passing the centre
of the earth, “il punto al qual si traggon d’ogni parte i pesi.”[741]
Virgil turned here “con fatica e con angoscia,”[742] and bid Dante hold
him fast, “ansando com’ uom lasso.”[743] It was natural to suppose that
the force of gravity would increase as one neared the centre, though
the fact is that it decreases. In deep mines it is less than at the
surface of earth; and if we could go to much greater depths we should
find that we could stand in any position, and walk in any direction
with almost equal ease, till at the exact centre the sense of weight
and of “up” and “down” would vanish altogether. This is because it
is the whole mass of the earth which attracts, and when we penetrate
beneath the surface the part above is no longer dragging us down, and
its effect is annulled. But at the surface gravity acts as if the
force were all concentrated at the centre, and falling bodies increase
their speed as they approach the surface: before the days of Newton,
therefore, it was thought that the whole of the attracting force was
actually situated at the centre of the earth. Brunetto Latini speaks
of gravity increasing as this point is approached, and Dante, like
Aristotle, calls it the goal of gravity.[744]

------------------------------------------------------------------------
[741] “The point towards which weights are drawn from every direction.”
_Inf._ xxxiv. 110-111.

[742] “Laboriously and painfully.” _Inf._ xxxiv. 78.

[743] “Panting like a tired man.” _Inf._ xxxiv. 83.

[744] _Qu._ xvi. 54, 55.
------------------------------------------------------------------------

Between the physical and the spiritual universe as conceived by
Dante, there is a very close correspondence. Souls burdened with the
weight of sin fall towards the centre of the universe, sinking deeper
the heavier is their guilt, and at the bottom of the whole universe
is the personification of all evil. Repentant souls, as they are
freed from their sins, rise higher and higher, and the ascent becomes
always easier, until at last they soar heavenward as naturally and
spontaneously as flames of fire. In Paradise the motion of the pure
spirits is inconceivably rapid, and their mystic dances expressive of
joy are always in circles.

Motion in circles was the only appropriate kind for the heavenly
bodies,[745] but the actual force which originated and preserved their
motions was intelligence and will. When Dante sang, “Voi che intendendo
il terzo ciel movete,”[746] he was not addressing beings created merely
by his poet’s imagination. His own commentary on the words shows
us that they were as real to him as the planets themselves. He can
know nothing of them through the senses, yet is as certain of their
existence as one with closed eyes is of light.[747] These beings move
the spheres not through any material contact, but solely by the power
of thought: they are immaterial immortal intelligences, commonly called
Angels, and Dante identifies them with the Forms of Aristotle, the
Ideas of Plato, and the gods and goddesses of the Pagans, “avvegnachè
non così filosoficamente intendessero quelle come Plato.”[748] As the
hammer beats out forms in metal, and thus expresses what is in the
mind of the smith, and as he works from the artist’s design, so the
movements and “virtues” of the sacred spheres mould earthly events, but
these movements and virtues are the expression of controlling angels,
and they are carrying out the Will of the First Mover. And as the joy
of a happy mortal shines out in the eyes, so the joy of the angels
shines out in stars and planets.[749]

------------------------------------------------------------------------
[745] This is nowhere stated, but everywhere taken for granted, and
in _Conv._ II. xiv. 211 the circle is said to be the most perfect of
figures.

[746] “Oh ye whose intellectual ministry moves the third heaven.”
_Conv._ II. canzone; and _Par._ viii. 37.

[747] _Conv._ II. v. 119-126.

[748] “Although they did not think of them as philosophically as
Plato.” _Conv._ II. v. 5-37, 94, 95; vi. 154-159.

[749] _Par._ ii. 127-129, 142-144.
------------------------------------------------------------------------

There were nine Orders in the angelic hierarchies, according to the
teaching of the Church, the chief authority on this subject being
a book _De Celestia Hierarchia_, supposed to have been written by
Dionysius the Areopagite, a disciple of St. Paul, who had learned from
the apostle what he had seen when rapt to the third heaven. Aquinas
assigns to one of these nine orders the guidance of stars and planets,
and to others the rule over earthly affairs. But since the latter
follow the celestial motions, there was no need to separate the two
functions, and Dante laid down in the _Convivio_ that a few Angels from
each Order preside over the movements of each sphere. With Aristotle,
he agreed that there is one Intelligence for each movement, so that for
Venus (for instance) there are three movers to direct respectively the
circling of the Epicycle, the Deferent, and the movement of Precession
which every planet shares with the stars; but whether there is a fourth
mover to guide the diurnal motion of Venus or if all the inner spheres
are swept along by the motion of the Primum Mobile, he would not
presume to decide.[750]

When he wrote the _Paradiso_, he no longer thought that a few Angels
were set apart for this ministry: he implies that all the angels in
each order united in the act of moving a whole heaven and perhaps he
means to include the beatified human spirits as well.[751] He also
slightly changes the correspondence between the angelic orders and
their respective spheres.[752]

Swiftness of motion in a sphere corresponds with fervour of adoration
in the Movers: hence the highest and swiftest of the moving heavens,
which is the Primum Mobile, is moved by the highest Order, the
Seraphim: and the lowest and slowest, which is that of the moon, by the
lowest order, the Angels.[753]

------------------------------------------------------------------------
[750] _Conv._ II. v. and vi.

[751] _Par._ viii. 34-37.

[752] _Cf. Par._ xxviii. 98 to end, with _Conv._ II. vi. 43-55,
106-109.

[753] _Par._ xxviii. 34-39, 64-75.
------------------------------------------------------------------------

All these movements are a proof of the existence of a First Mover,
Himself unmoved, as Aquinas had said, following Aristotle, and the
first words of Dante’s confession of faith in Paradise are an echo of
this:—

            “Io credo in uno Iddio,
    Solo ed eterno, che tutto il ciel muove,
    Non moto, con amore e con disio.”[754]

------------------------------------------------------------------------
[754]
                  ”In one God I believe,
    Sole and eterne, who moveth all the heavens,
    With love and with desire, Himself unmoved.”
                    _Par._ xxiv. 130-132. (_Longfellow_).
------------------------------------------------------------------------

Here, as often elsewhere, Dante identifies the heavens with their
Movers, and speaks as if the spheres themselves were moved by love and
longing. In the tenth heaven, or Empyrean, this longing was completely
fulfilled, hence this heaven was for ever at rest.[755]

------------------------------------------------------------------------
[755] _Conv._ II. iv. 13-30; _Ep._ x. 442-452, and 472-488; _Par._ i.
121-123.
------------------------------------------------------------------------




_VIII. MEDIÆVAL AND MODERN VIEWS OF THE UNIVERSE._


MEDIÆVAL AND MODERN VIEWS OF THE UNIVERSE.

Let us now gather into one picture the details of mediæval astronomy
which Dante has taught us, and try to see the universe as it presented
itself to men’s minds in his days.

Motionless, at the centre of all things, is the earth, a massive globe
20,400 miles in circumference.[756] Only the northern part of one
hemisphere is inhabited; the rest is covered by ocean. It is surrounded
by air, into which rise the exhalations from land and sea which cause
winds, rain, etc. Above the height to which these rise, and above the
tops of the highest mountains, the air sweeps uninterruptedly round the
earth from east to west, sharing the movement of the skies. Above this
again is the region of pure fire: all fire on Earth’s surface tends to
rise into it, and hot dry vapours ascending here burst into flame, and
are seen from Earth as shooting stars and comets.

------------------------------------------------------------------------
[756] Probably equal to 26,500 English statute miles.
------------------------------------------------------------------------

Bounding the sphere of fire is the lowest of the celestial spheres,
that of the moon; and here we pass abruptly from the world of the
four elements, transitory, changing, to the celestial world, eternal,
changeless. Sphere rises above sphere, carrying moon and sun and
planets, until we reach the vast orb in which are set all the stars.

All these bodies are composed of a mysterious imponderable substance
called æther; all are perfectly spherical, and all their movements are
circular. The diurnal rotation which we see is caused by an outermost
sphere which contains no star: it communicates its own motion to all
the spheres within it. The zodiacal motions of sun, moon, and planets,
and the precession of the equinoxes, are caused by the proper motion of
each sphere, rotating from west to east. The oscillating movements of
the five planets and the varying speed of the moon are caused by small
rotating spheres called epicycles, on which planets and moon are fixed,
the epicycles in their turn being attached to the large spheres.

The distance from the earth to the nearest heavenly body, which is the
moon, is 64⅛ times the radius of the earth; the distance of the fixed
stars, more than 20,000 times the radius of Earth.

Mercury, the smallest of the heavenly bodies, is only 232 miles in
diameter,[757] the moon and Venus are both rather more than a quarter
the size of the earth, Mars is a little larger than Earth; next in
order of size come the stars, from the faintest visible increasing up
to those of the second magnitude; Saturn and Jupiter are much larger
than Earth, and the fifteen brightest (first-magnitude) stars larger
still; the sun is the largest body in the whole universe, having a
diameter 5½ times Earth’s diameter. It is immensely bright and hot, is
the source of light to the whole universe, and on Earth is the chief
giver of light, heat, and life, and the chief measure of time.

------------------------------------------------------------------------
[757] 300 English statute miles.
------------------------------------------------------------------------

The moon and stars are also useful in this way to Earth, and upon her
are poured all the influences of the celestial spheres, the sun, moon,
and planets: these are the instruments by which every event on Earth is
brought to pass.

It is their nature to move in circles, as it is Earth’s nature to
remain motionless at the centre of the universe; but all their motions
are controlled by the wills of immortal angels, which are subject to
the Will of the First Mover.

The sensible universe is eternal, but it is finite and measurable, and
of definite form,[758] being bounded by a sphere. Beyond this in every
direction is infinity.

------------------------------------------------------------------------
[758] _Conv._ IV. ix. 23-25.
------------------------------------------------------------------------

Such was the mediæval conception of the Universe, as we gather from
learned mediæval books, and as we find it vividly pictured in Dante’s
glowing verse. How do we conceive it now?

The heavens are the same to our eyes as to Dante’s. The blue dome of
the sky still arches over our heads, and in it we may see the stars
shine out after the sun has set; we may see Venus making all the orient
smile at early dawn, and the light of the moon not yet risen paling the
stars of Scorpio. We may also see with our bodily eyes what was only
visible to the keen eyes of Dante’s mind, the rising sun travelling
to our left, and the southern stars circling round the southern pole,
while the stars of the north sink below the ocean floor.[759]

------------------------------------------------------------------------
[759] Compare with Dante’s accurate descriptions a poem by Kipling in
“A School History of England”:—

    “South and far south below the line
     Our Admiral leads us on.
     Above, _undreamed-of planets_ shine.” (!)
------------------------------------------------------------------------

But to one who knows anything of modern astronomy the ideas suggested
are widely different. Most striking is the absence of that sharp
contrast between Earth and heaven which our forefathers felt. Earth
is not to us small, dark, and inert, made of the basest material and
sunk, like the dregs of the Universe, to its lowest depths. Earth is
a heavenly body, as the Pythagoreans rightly guessed, a beautiful big
planet, shining brightly by reflected sunlight and moving swiftly, like
her sister-planets. To Venus she is the brightest star in the sky; to
the moon she shows a far larger disc than the moon shows to us, and
markings more beautiful and wonderful, brilliant caps of snow at either
pole, oceans coloured blue-green, and continents varying in tint,
whenever the dazzling white clouds part to reveal her surface.

Earth is the largest planet among her neighbours, Mercury, Venus, and
Mars; just as Jupiter is largest among the giant planets—Saturn and the
more recently discovered Uranus and Neptune. In the gap between these
two groups modern astronomers have discovered hundreds of tiny planets,
to which Earth is a monster, for many are only a few miles in diameter.
The meteorites which shoot across our view, “startling quiet eyes,” we
still regard as a kind of conflagration in our upper atmosphere, but
instead of vapours rising from Earth’s surface we recognise them as
visitants from inter-planetary space, caught by Earth’s great mass as
they pass too near, and flaming up with the heat caused by their sudden
rush through the air. They exist in shoals of thousands and millions,
some small as pebbles, some like great rocks, but all belonging to
our system and pursuing definite paths like planets. The same must be
said of comets, which have just as little to do with a hypothetical
fire-sphere round Earth, but travel in regular periods, some long,
some short; several small ones are seen every year, and occasionally a
great splendour like Halley’s draws near to us in its orbit, yet even
these seem to consist of very small quantities of matter. Other members
of our celestial family are the moons of Mars, Jupiter, and the rest,
of which more are still being discovered. The Earth-Moon system is,
however, unique in that our satellite is much nearer our own size than
the proportionately tiny companions of other planets and the pair must
look like a beautiful “double” moving through the stars and continually
revolving round one another.

[Illustration: Fig. 53. Comparative sizes of the Sun and his
satellites. _p. 490_]

All these bodies are made, not of a mysterious ether, but of something
just as wonderful, beautiful, and incomprehensible—the same stuff as
Earth. Most probably all developed in long-past ages out of a nebula,
or mass of gas which for some unknown reason was intensely hot. Small
bodies, like the Moon and Mars, cooled off the most quickly, and have
lost or are losing their air and their water; larger bodies, like
Jupiter, have still some heat, and are probably in a more or less fluid
condition. On the sun an inconceivable heat still rages; everything is
in a gaseous state, and this globe which men used to think eternally
changeless is the scene of the fiercest turmoil; currents are always
ascending and descending, clouds of fire are flung up thousands of
miles high, and patches which look black compared with the surrounding
surface and indicate a mysterious commotion are constantly forming,
developing, and disappearing. The sun is enormously larger than Dante
thought, larger than all the planets put together, large enough for
our moon’s whole orbit to fit comfortably inside. It is hot enough
and brilliant enough to light all the planets: this, which was only
a guess of mediæval astronomers, we know as a fact to-day, and the
planets which are suitably placed show it to us, when seen in the
telescope; Venus, for instance, changing her phase “according as the
sun looks upon her,” exactly like the moon. And Earth must show similar
phases as seen from Mars.

For Aristarchus was right: the sun is the centre of the planetary
movements, including those of the planet Earth.

We saw how Ptolemy’s system hinted at this, in the significant
connection between each planet’s movement and the movement of the
sun; but a strong argument against it was that if Earth were really
moving round the sun we ought to see a yearly displacement in the
positions of all the stars. Modern instruments have at last made it
possible to perceive this displacement. About a hundred stars, our
nearest neighbours, describe a very minute orbit in the sky, which in
every case is an exact reflection of the sun’s apparent orbit round
the earth. Unless, therefore, we are going to provide all these stars,
as well as the planets, with epicycles, which must all revolve in the
same period, in the same direction, and in parallel planes, we must
conclude that the movement is really Earth’s yearly movement round the
sun. These miniature star-orbits also show us the stupendous distances
which lie between Earth and the nearest stars, while by far the greater
number are too remote to show any displacement at all.

Aristarchus and those other ancient astronomers were also right who
thought that Earth was turning on her axis, and thus producing by her
own motion the alternation of day and night, and the apparent circling
of the stars. When we look now at stars hastening across the sky,
they no longer present themselves to our thought as fixed on a sphere
with a radius of 20,000 Earth-radii, which is revolving round us at a
tremendous speed; we feel that we are looking into space at glowing
globes which are at various and almost inconceivable distances from
us; also that all those we see, all those that Hipparchus numbered,
are but an insignificant fraction of all those now known to exist.
All have their own real motions, as well as the apparent motions
produced by Earth, but these are in different directions, towards what
goal we cannot at present tell. Compared with them, Earth is indeed
insignificant, in size and also in brightness, for while she shines
with reflected light they glow as the sun does and are his peers.

Nevertheless, with them too we have a feeling of kinship, for analysis
of their light shows that they too are made of earth-stuffs: they are
not eternal nor changeless, for very many vary constantly in their
light, and they are at different stages of development, some appearing
very young, while others are beginning to burn dim and low, and some
can only be inferred to exist, for they seem to be wholly dark.

More wonderful perhaps than anything else, we find that the force
which binds the whole of our sun’s family together is nothing strange
and unknown, but the same familiar force of gravity, which the Greeks
knew so well but thought only applicable to Earth. Its rule includes
the seemingly unruly comets and meteors, and it extends as far as our
search can reach, to the uttermost star.

This sense of unity throughout the world, which is always growing
stronger, is comforting. And we allow ourselves to wonder whether
intelligent life has not developed elsewhere, as well as on this globe
that we inhabit. Perhaps each planet that attends our sun is fitted at
some period to be the abode of life: surely among the millions of stars
many must have attendant planets, and on some of them even now are
living, thinking, beings.

Dante’s world was easier to think about than ours. Encompassed by an
infinity which gave the imagination free scope, the material universe
within was neatly rounded off, as it were, complete, finished. Only
in the central spot was any development taking place, and thither
were directed all effects of the circling spheres. Our universe is
vague, vast, mysterious, without known limits or centre, offering
problem after problem to the thinker. Dante’s marvellous moon-substance
is simple compared with the baffling nature of our æther; Dante’s
Angel-Movers are intelligible compared with the amazing mystery of
universal gravitation.

Yet when we lift our eyes from earth to heaven, we share the feeling
of our mediæval forefathers, of the ancient Greeks, of the earliest
men whenever and wherever they became men. The unerring courses of
the stars speak to us, “the unperturbed to the perturbed,” of perfect
harmony, untouched by chance or arbitary conflicting wills. Now,
however, we do not believe this is because heaven is essentially
different from earth: it is because we see there only the grand
outlines, only the working of great laws, of a system which includes
our own earth. Could we but lose sight of the details here, and view
the history of man as we view the stars, the harmony would be as grand.


HYMN TO ZEUS.

    Most glorious of the Immortals, many-named, Almighty for ever,
    Zeus, Ruler of Nature, that governest all things with law,
    Hail! for lawful it is that all mortals should address thee.
    For we are thy offspring, taking the image only of thy voice,
          as many mortal things as live and move upon the earth.
    Therefore will I hymn thee, and sing thy might for ever.
    For thee doth all this universe that circles round the earth
          obey, moving whithersoever thou leadest, and is gladly swayed
          by thee.
    Such a minister hast thou in thine invincible hands—the
          two-edged, blazing, imperishable thunderbolt.
    For under its stroke all nature shuddereth, and by it thou
          guidest aright the universal Reason, that roams through
          all things, mingling itself with the greater and lesser
          lights, till it has grown so great, and become supreme
          king of all.
    Nor is aught done on the earth without thee, O God, nor in
          the divine sphere of the heavens, nor in the sea,
    Save the works that evil men do in their folly.
    Yea, but thou knowest even to find a place for superfluous
          things, and to order that which is disorderly, and things
          not dear to men are dear to thee.
    Thou dost harmonize into one all good and evil things, that
          there should be one everlasting Reason of them all.
    And this the evil among mortal men avoid and heed not
          wretched, ever desiring to possess the good; yet they
          nor see nor hear the Universal Law of God, which,
          obeying with all their heart, their life would be well.
    But they rush graceless each to his own aim,
    Some cherishing lust for fame, the nurse of evil strife,
    Some bent on monstrous gain,
    Some turned to folly and the sweet works of the flesh,
    Hastening indeed to bring the very contrary of these things to pass.
    But thou, O Zeus, the all-giver, dweller in the darkness of cloud,
          lord of thunder, save thou men from their unhappy folly,
    Which do thou, O Father, scatter from their souls, and give them to
          discover the wisdom, in whose assurance thou governest all
          things with justice;
    So that, being honoured, they may pay thee honour,
    Hymning thy works continually, as it beseems a mortal man,
    Since there can be no greater glory for men or gods than this,
    Duly to praise for ever the Universal Law.
                                       CLEANTHES (3rd century B.C.).
                                    _Translation by T. W. Rolleston._




INDEX.

(Pages 1 to 206 are in Part I.: 207 onwards, in Part II.)

     Abrachis (Hipparchus), 193
     Abul Hazan, 184
     Abul Wefa, 183, 194
     “Acerba,” 227, 243
     Achernar, 12, 155, 156, 295
     Achilles, Shield of, 53
     Adam, 349, 438
     Albategnius, 183, 193, 202, 239, 275
     Albertus Magnus, 204, 232, 237, 239, 241, 292,
                      306, 324, 342, 432, 443, 454
       ”  and meteors, 319
     Albert of Saxony, 464, _n._465
     Al Betrugi (Alpetragius), 184
     Albumassar, 239, 245, 443, 473
     Alchabicius, 202
     Alchemy, 212-13, 215
     Aldebaran, 155, 156
     Alexander the Great, 79, 80, 112, 145
     Alexandria, 113, 118, 122, 134, 135, 156, 157, 172
        ”  Astronomers of, 122, 124, 137, 153, 163, 171, 175, 288
        ”  Museum and observatory of, 113, 114, 116, 117, 122, 135
        ”  School of, 112 _et seq._, 163
     Alfarcatein, 187, 234
     Alfonso X., 195, 203, 242
     Alfraganus, 183, 233-37, 243
        ”     editions of, 235, 437, _n._458
        ”     geography of, 337
        ”     writings of, 184 _et seq._, 193-4
        ”     and climates, 324, 397
        ”      ”   colure, 403
        ”      ”   Dante, 253, 254, 273, 275, 286, 288-90, 299, 313,
                          315, 328, 335, 347, 403, _n._403, 436-37,
                          444, 448-51, 458-9
        ”     and eclipses, 338
        ”      ”   meteors, 320
        ”      ”   moon, 349, 448-49
        ”      ”   precession, 288, 439
        ”      ”   Regulus, 406
        ”      ”   Ristoro, 245-47
     Algazel, 245
     Almagest, 114, _n._115, 123, 136, 154, 159,
               163, 182, 184, 193, 209, 218, 232, 238
        ”     translations of, 201-2
     Al Mamun, 182, 185, 186, 192
     ‘Almanach Dantis Aligherii,’ 421-23
     Al Mansur, 181
     Alpha Draconis, 127
     ” Centauri, 155, 191
     ” Phœnicis, 156
     Amerigo Vespucci, 294
     Anaxagoras, 60, 61, 76, 98, 239, 305
     Anaximander, 26, 56, 66, 75, 76, 91, 99
     Anaximenes, 60, 98
     Andrea Corsali, 294
     Angelitti, Prof., 281, 410, 415, 417, 423
     Angels, 249, 284, 302, 311, 388, 414-15, 441, 477, 482-84, 489, 494
     Angelo de Gubernatis, _n._399
     Anomaly, of planets, 140, 143
     Antæus, 371
     Antares, 30
     Antichthon, 71, 75, 101, 236
     Antipodes, 66, 176, 324
     Antonelli, _n._295
     Apogee, 119;
       of moon, 148, 449, 450;
       of sun, 146, 193
     Apollonius, 118, 141
     Aquarius, 33, _n._36, 145, 149, 156, 277, 290, 385
     Aquila, 12
     Aquinas, St. Thomas, 201, 204 _et seq._, 211, 237, 238,
                          241, 306, 339, 454, 479, 483, 484
     Arabs (_see also Mahomedan_)
       ”  astronomers, 218;
          year, 39;
          zodiac, 30
       ”  and astrology, 213;
          astronomy, 181 _et seq._
     Aratus, 25 _Note_, 31, 32, 34, 35, _n._35, 58, 168
     Archimedes, 107
     Arcturus, 36, 52, 155, 190, 191
     Arculf, 176
     Argo, _n._36
     Aries (_see also Ram_), 40, _n._43, 265, 279, 281, 290,
                       325, 356, 368, 373, 374, 387, 398, _n._399
       ”  first point of, 129, 185, 277, 357, 403, 404
       ”  and astrology, 249
       ”   ”  Jupiter, 418
       ”   ”  Mars, 476
       ”   ”  Sun, 277, 278, 281, 323, 325, 333, 367, 368, 383, 396,
                   398, 402-5, 418, 419, 422, 473
     Aristarchus, 107 _et seq._, 111, 120, 121, 153, 191, 492
     Aristophanes, 162
     Aristotle, 58, 66, 95 _et seq._
       ”   cosmogony of, 101-02, 103 _et seq._, 123, 160, 201, 204
       ”   influence on science, 80, 136, 182, 184, 193
       ”   translations of, 214, 237
       ”   and Arabs, 184
       ”    ”  Averroës, 463
       ”    ”  Calippus, 95, 107
       ”    ”  the Galaxy, 237, 305, 306
       ”    ”  Dante, 235-38, 241, 254-55, 261, 301, _n._321, 342,
                              431, 442, 451, 454, 464-65, 480-84
       ”    ”  gravity, 445
       ”    ”  Latin authors, 170
       ”    ”  Mars, 310, 433
       ”    ”  meteors, 319, 321
       ”    ”  music of the spheres, 455
       ”    ”  Plato, 85
       ”    ”  southern hemisphere, 353
       ”    ”  spheres 431, 432, 434, 461
     Aruns, 472
     Aryabhata, 110-11
     Arym, 247, 329
     Arzachel, 184, 195
     Asdente, 212, 472
     Assisi, St. Francis of, 271
     Astrolabe, 114, 115, 122, 144, 192, 202, 203, 341
       ”   invention of, 115, 133
     Astrologers, 213, 231, 369, 419, 469, 476
       ”   of Brescia, 211;
       13th century, 216
     Astrology (_see also Star Influence_, and _Astronomy, Judicial_),
                         6, 45, 47, 157, 161, 172, 211 _et seq._, 218,
                         243, 245, 249, 308, 471, 476, 478-9
       ”   Arab, 183, 200, 213
       ”   books on, 202-3
       ”   Egyptian, 113, 157
       ”   Jewish, 213
       ”   professors of, 200
       ”   and planets, 211
     Astronomy, Alexandrian, 112 _et seq._, 218, 231, 288, 335
       ”   Arab, 181 _et seq._, 190, 204, 232, 239, 243, 245, 461-3
       ”   Babylonian, 40 _et seq._, 209, 421 (_see also Babylonians_)
       ”   Chinese, 29 _et seq._, 115
       ”   Egyptian, 209 (_see also Egyptians_)
       ”   Greek, 209, 236, 314, 445, 461 (_see also Greeks_)
       ”   Indian (_see Hindu, and India_)
       ”   judicial, 124, 213, 233, 261 (_see also Astrology_)
       ”   Moorish, _n._200, 203
       ”   Persian, 195
       ”   primitive of, 25 _et seq._
       ”   in Spain, 183, 194
       ”   taught by Church, 176
       ”   personified, 217
       ”   and Dante, 1
     Atlas, 98;
       Mt. Atlas, 53
     Augustine, St., 175, 238, 239, 479
     Augustus, Emperor, 171, 175, 319, 359
     Auriga (Charioteer), 144
     Averroës, 184, 204, 232, 239, 246, 342, 432, 462
     Avicenna, 202, 239, 247, 305

     Babylon, 69, 80, 156, 181
     Babylonia, 18, 36, 81
     Babylonians, 36-38;
         astronomers, 110, 125, 127, 144, 161
       ” and astronomy, 43-4
       ”  ”  calendar, 40 _et seq._
       ”  ”  cosmogony, 45, 46, 47, 48, 55, 57
       ”  ”  day division, 27
       ”  ”  eclipse records, 80, 81, 144
       ”  ”  gnomon, 26
       ”  ”  occultations of planets, 105
     Bacon, Roger, 202, 249, 275, 292, 342, 343
     Baghdad, 141-3, 181 _et seq._, 245, 432
       ”   astronomers, 194-5
       ”   observatory, 142 (_see also Arab Astronomers_)
     Bartolommeo della Scala, 226, 227
     Bear: Great, 12, 25, 36, 52, 56, 157, 187, 297-8, 334;
       Little, 25, 56, 187, 297-98, 334
                     (_see also Ursa Major and Minor_)
     Beatrice, 1, 253, 237, 284, 376, 390, 392, 394, 401, 441, 455, 473
       ”  age of, 253, 288, 413-4
       ”  death of, 224, 253, 254, 314, 316, 414
       ”  Dante’s first meeting with, 253, 272, 273
       ”  guiding Dante, 262, 330, 367, 373, 392, 393, 400, 401
       ”  and Moon, 462, 475
       ”   ”  Sun, 271, 392
     Beazley, _n._342, _n._384
     Bede, 178, 250, 454
     Belacqua, 376
     Benet Naax, 187, 234
     Benevento, 242
     Benvenuto da Imola, 383, 418
     Betelgeux, 155
     Boccaccio, 224, 225, 228, 231, 274, 413, 414, 418, 422
     Boëthius, 1, 177, 284, 296
     Boffito, Prof., 423
     Bologna, 199 _et seq._, 227, 277 (_see also Universities_)
     Boötes, 52, 284, 298
     Borneo, natives of, and gnomon, 26
     British Astronomical Association, Journal of, _n._29, _n._34
       ”   Museum, 36, 40
     Brown, Robert, 24 _Note_, 32, _n._34, 35, 156
     Brunetto Latini, 218, 225-6, 241-2, 248-9, 274-5, 292, _n._349,
                      369, 414, 470, 473, 481
     Bull, _see Taurus_

     Cacciaguida, 3, 313
     Calendar, 29, 36, 47;
           Ancient, 33, 34
       ”   Arab, 39, 184
       ”   Babylonian, 40, 41, 127
       ”   Berber, Persian, Syrian, 184
       ”   Chinese, 39
       ”   Ecclesiastical, 176, 203
       ”   Egyptian, 39, 184
       ”   Greek, 161, 162, _n._172
       ”   Hindu and Parsee, 127
       ”   Julian, and Roman, 171, 176, 184, 274 _et seq._
       ”   luni-solar, 176
       ”   Mahomedan, 39
     Calippus, 93, 107, 145, 162;
       cycle, 172
     Callisthenes, 80
     Campaldino, 224
     Cancer, 145, 174, 185, 269, 277, 280-2, 325, 394, 397
     Can Grande della Scala, 416, 426, 441, 473
     Canopus, 12, 67, 134, 155, 295
     Canton, 27
     Capella (star), 155
       ”   Martianus, 170, 177
     Capricornus, 33, 43, 144, 185, 277, 282, 325, 342, 360, 374
     Carnac, 29
     Casella, 374, 414, 426
     Cassiodorus, 177
     Cassiopeia, 12
     Castor and Pollux, 43, 290, 333
     Catalano, Friar, 227
     Cato, 373-4
     Cecco d’ Ascoli, 200, 216, 226, _n._227, 241-4, 249, 478
     Celestial Movements, 9-20, 25, 28, 29, 38, 47, 56, 62, 65, 86,
                          102-3, 105, 136 _et seq._, 159, 174,
                          209, 248, 261-4, 299, 357, 367, 409, 429,
                          430, 432, 438, 457, 483, 487
       ”  direct, 16, 147
       ”  and Alfraganus, 185 _et seq._
       ”   ”  astrology, 211
       ”   ”  Brunetto Latini, 243
       ”   ”  tables of, 22, 23
       ”   ”  daily, 13
       ”   ”  retrograde, 16, 18, 44, 116, 147
     Centaur, _n._36, 294;
       Alpha Centauri, 155
     Central Fire, 75, 85, 101, 102, 109, 159
     Cetus, _n._36
     Chalcidius, 238
     Chaldea, 172
     Charioteer, _see Auriga_
     Charlemagne, 178, 182
     Charles of Hungary, 256
     Charles of Valois, 318
     Chinese, and comets, 45;
       gnomon, 20, 114;
       year, 38;
       zodiac, 29, 31
     China, 291, 343
     Christian Era, Introduction of, 177
     Church, Catholic, 210, 216, 219, 335, 346-8, 410,
                       419, 431, 432, 480, 483;
       and spheres, 433
     Cicero, 1, 109, 167-8, 171, 217, 237-9
     Cleanthes, 496
     Cleomedes, 135, 457
     Clepsydra, 27, 115, 122, 133, 141
     Climates, 158, 186, 187, 247-8, 324, 347, 397
     Clocks, pendulum, 16;
       water, 27, 115 (_see also Clepsydra_)
     Colure, 185, 403
     Comets, 45, 66, 103, 174, 175, 176, 262,
             318 _et seq._, 487, 490, 491
     “Composizione del Mondo,” 244 _et seq._, 292
     Conjunction, 24, 142, 191
     “Consolations of Philosophy,” 1
     Constantine, 262
     Constantinople, 201
     Constellations, 454;
          ancient, 33, 34, 80
       ”  Arab, 30, 188, 234
       ”  Egyptian, 34;
          Hebrew, 34;
          Hindu, 30
       ”  figures of, 115, 154-55, 168, 246, 248, 289, 443, 451
       ”  influences of, 246, 451
       ”  naming and origins of, 24 _Note_, 32, 33, 36, 47,
                                 51, 80, 161
       ”  southern, 246
       ”  and Astrology, 211
     “Convivio,” 255, 258, 357, 464, 466, 468, 476
     Copernicus, 66, 111, 136, 210
     Cordova, 183
     Corona Borealis, 299
     Corsica, 344, 383, 384
     Corvino, 293, 343
     Corvus, _n._36
     Cosmas Indicopleustes, 175
     Cosmogonies, Ancient, 45, 63, 160;
       Babylonian, 45, 53, 57;
       Egyptian, 45, 53, 83, 109;
       Hebrew, 45, 47;
       Hindu, 45;
       Homeric, 53 do. of Anaximander 58-59;
       Aristotle, 103;
       Cosmas, 175;
       Democritus, 63;
       Eudoxus, 88;
       Leucippus, 63;
       Philolaus, 70;
       Plato, 83;
       Ptolemy, 150;
       Pythagorean, 66-75;
       Thales, 55, 56
     Coulton, _n._212
     Creation, 403, 411, 419
     Crystal Spheres, 74, 159 (_see also Spheres_)
     Cunizza, 415, 426, 472
     Cycles, 45, 55
     Cyprus, 102

     Dante, birth of, 211, 273, 413, 426;
         childhood, 223;
         as Councillor, 224, 414;
         as Prior, 224;
         in exile, 224;
         in Ravenna, 224, 273;
         in Mantua, 444;
         in Rome, 224, 318;
         in Verona, 256, 444;
         death, 165, 216, 224, 273
       ” studies, 223 _et seq._;
         quoted, 25
       ” shadow of, in Purgatory, 374, 387-8
       ” wife of, 224-5
       ” and Alfraganus, 234, 254, 289, 449;
              Asdente, 212
       ”   ”  Aristotle, 96, 102, 105, 235, 241, 254, 480, 482
       ”   ”  ancient writers, 57, 62, 70, 82, 86
       ”   ”  astrology, 261;
         and astronomy, 25
       ”  ”  Brunetto Latini, 225, 226, 242
       ”  ”  Beatrice, 1, 273
       ”  ”  calendar, 274, 275
       ”  ”  Date of Vision, 357, 409 _et seq._
       ”  ”  Classical authors, 237 _et seq._
       ”  ”  Frederick II., 214
       ”  ”  Greek astronomy, 105, 262, 306
       ”  ”  philosophers, 461
       ”  ”  Homer, 209
       ”  ”  geography, 337, 339 _et seq._
       ”  ”  Jerusalem, 176
       ”  ”  Michael Scot, 215
       ”  ”  Milton, 210
       ”  ”  Moon, 265 _et seq._
       ”  ”  music of the Spheres, 455-6
       ”  ”  precession, 274 _et seq._, 439
       ”  ”  Philosophy, 255
       ”  ”  Ptolemy, 135, 154, 209, 232, 256, 458-9, 468
       ”  ”  Roman Empire, 167, 178
       ”  ”  science, 1, 219, 258
       ”  ”  the Acerba, 244
       ”  ”  stars, 283 _et seq._
       ”  ”  southern stars, 293-5
       ”  ”  universities, 226 _et seq._
     “Dante e gli Astronomi Italiani,” _n._235, _n._315
     Day, Arab, 253;
       definitions of, 14, 22, 25, 26;
       divisions of, 52, 161;
       length of, 186;
       sidereal, 12,
         definition of, 22;
       solar, 12;
       Church, 348
     Decimal Notation, introduced, 182
     Declination, definition of, 126
     “De Cœlo” (“On the Heavens”), of Aristotle, 96, _n._96, 105,
                                     170, _n._232, 236, 431, 464
       translations of, 214
     “De Cœlo” of Albertus Magnus, _n._232, 342
     Deferent, definition of, 138; 145, _n._149, 193
     Degrees, invention of, 44
     Delambre, _n._35, _n._126, 149, 156, _n._460
     Della Lana, Jacopo, 418
     Della Valle, _n._398
     Del Virgilio, 227
     Democritus, 64 _et seq._, 98, 239, 305
     Denebola, 155
     “De Substantia Orbis,” 184
     Dicuil, 178
     Dilgan, 40, 42, 127
     Dionysius Exiguus, 177
        ”    the Academician, 239
        ”     ”  Areopagite, 483
     Direct Motion, 16
     Divine Comedy, 237-8, 353, 402, 409
     Dominicans, 204, 241
     Domitian, 171
     Dream of Scipio, 109, 169, 237
     Dreyer, _n._460
     Dupuis, 34

     Earth, 393, 395, 398-401, 490, 491
       ”   centre of, 353, 372, 424, 481
       ”      ”   of universe, 66, 75, 83, 84, 85, 88, 91, 96, 98, 99,
                               100, 109, 112, 120, 137, 160, 169, 185,
                               203, 205, 209, 219, 431, 444, 461, 489
       ”   Counter-, _see_ Antichthon
       ”   dimensions of, 71, 102, 117, 118, 134, 157, 160, 169,
                          182, 185, 186, 190, 216, 458, 487, 490
       ”   distance from sun, 108, 189
       ”   form of, 56, 59, 63, 66, 67-8, 71, 72, 83, 91,
                    96, 98, 100, 160, 175, 185, 186
       ”   habitable part, 205, 247, 248, 335, 342, 353, 369, 372,
                           391, 397, 398, 436, 444, 446, 451, 487
       ”   in equilibrium, 100
       ”   measurement of, 103, 117, 134
       ”   motion of, 17, 66, 70, 71, 85, 88, 99, 101, 142, 186;
       ”   movement of, 431, 438
       ”   resting on air, 63;
           on water, 56, 98
       ”   revolution round sun, 13, 66, 107, 109, 110, 120,
                                 146, 159, 210, 256, 492
       ”   rotation on axis, 13, 72, 75, 85, 88, 101, 108,
                             110, 136, 159, 210, 492
       ”   shadow of, 67, 96, 191, 346, 459, 460
       ”   spherical form of (_see also_ form of earth), 102, 209, 219,
                                                               237, 487
     Earthly Paradise, _see_ Eden
     Easter, 176, 177, 203, 275, 405, 418, 420, 422, 424
       ”   year, 415
     Ebn Jounis, 183
     Eccentrics, 118, 119, 121, 141 _et seq._, 193, 210, 235
     Eclipses, 18, 55, 57, 67, _n._76, 117, 168, 174, 175,
               192, 203, 262, 255 _et seq._, 266, 465
       ”   annular, 44
       ”   Babylonian records, 80, 96, 113, 144
       ”   lunar, 44, 45, 55, 67, 125, 185, 338, 340, 341, 469
       ”   solar, 245, 338
     Ecliptic, 18, 55, 117, 126, 129, 130, 145, 147, 185, 279,
               312, 325, 330, 331, 333, 397, 403, 404, 476
     Ecphantus, 75, 102
     Eden, 205, 295, 296, 334, 349, 353, 394, 401, 453, 454
       ”   Richard, 299
    ‘Egyptian System,’ 109, 120
        ”   year, 38, 45
     Egyptians (_also_ Egypt), 27, 28, 36, 45, 67
        ”   astronomers, 55, 56, 105, 124, 125, 144
        ”   astrology, 113, 120, 156
        ”   astronomy, 34, 45, 46, 51, 80, 113, 184
        ”   cosmogony, 45, 53, 55
        ”   and Eudoxus, 66, 88, 100, 151
        ”    ”  Pythagoras, 67
        ”    ”  eclipses, 45
    ‘Elementa Astronomica,’ 184, 234,  253, 273, 313, 320, 347
        ”   translations of, 234
     Elements, The Four, 62, 83, 103, 236, 441 _et seq._, 461, 478
        ”          ”    creation of, 441
        ”          ”    and Aristotle, 236, 442
     Ellipse, _n._94
     Elongation, Greatest, E. and W., 142;
       definition of, 15
     Empedocles, 60, 62, 98, 369
     Empyrean, 204, _n._232, 253, 296, 313, 353, 393, 401,
               433, 440, 444, 462, 447, 484
     Epicycles, def. of, 138 _et seq._, 121, _n._149, 187, 193, 194,
             210, 235, 256, 314, 429, 435, 449, 457, 466, 483, 488, 492
        ”   of Venus, 142, 435
     Epping and Strassmeier, _n._36
     Equator (celestial), 10 _et seq._, 18, 35, _n._35, 65, 115,
                         126, 130, 185, 323, 330, 334, 368, 383, 392,
                         397, 403, 404, 439, 448, 476
        ”   terrestrial, 238, 246, 247, 322, 324, 329, 336, 337, 342
     Equinox, 30, 124, 126, 274, 278, 282, 326, 330, 334, 340, 347,
              348, 349, 354, 356, 368, 372, 383, 387, 392, 402-7,
              410, 418, 420-3
       ”   date of, 26, 176, 177, 185
       ”   definition of, 12
       ”   observation of, 39, 94, 116, 124, 125
       ”   position of, _n._44, 185
       ”   precession of, 23, 24, 35, 125, 133, 135, 137, 161, 193, 194,
                       232, 275, 287, 356, 384, 432, 435, 439, 483, 488
       ”   and Alfraganus, 439
     Eratosthenes, 117, 134, 240
     Eridanus, (“The River”) _n._35, _n._36, 155, 156
     Eridu, 46
     Esdras, 342
     Ether, 104, 110, 137, 159, 193, 433, 461, 466, 480, 488, 491
     Ethiopia, 336;
       Ethiopians, 53
     Euclid, 118, 202
     Euctemon, 93, 161
     Eudoxus, 66 _et seq._, 34, 80, 235;
             spheres of, 90, 106, 107, 109, 112, 113,
                        118, 123, 141, 159, 161, 170
        ”    and Calippus, 93, 94;
             and Egypt, 80, 100, 159;
             and Plato, 81, 88, 159
     Eunoe, 366, 390, 392
     Evection, 147

     Farinata, 413, 417
     Fergil, 178
     Filelfo, 471
     Fire;
       Central, 431;
       sphere or region of, 58, 308, 442, 480, 487
     First Mover, 106, 159, 204, 254, 444, 478, 483, 484, 489
     Fishes (_see_ Pisces)
     Florence, 1, 158, 201, 211, 215, 216, 224, 225, 226, 242, 283,
                  318, 345, 350, 406, 411-14, 417, 421, 471
     Folco, 346, 459, 472
     Fomalhaut, 155, 156
     Forese, 367
     Forest, The, 266, 358, 367, 369, 378, 386, 406
     Francis, St., 271
     Frederick II., 202, 213 _et seq._

     Gades, 340, 345, 366, 395, 397
     Galaxy, 61, 103, 115, 154, 168, 232, 239,
             301, 303 _et seq._, 477
     Galileo, 107, 210
     Gallus, Sulpicius, 167
     Ganges, 205, 340-5, 360, 365, 388, 397, 400
     Gardner, E. G., 228
     Gemini (_see also_ Twins), 43, 44, 145, 149, 273, 280-1, 290,
             333, 366, 387, 393, 394, 397, _n._399, 404, 461, 473
     Geminus, _n._93, 134
     Genoa, 293
     Geography, 240, 344;
       Arab, 246, 247;
       Alfraganus’, 186;
       Ptolemy’s, 146, 157, 186
     Geryon, 369
     Ghibellines, 213, 227
     Giambullari, 419
     Giuliani, 280
     Gnomon, defined, 13, 26, 28, 47, 56, 114, 116, 122, 125, 161
       ”     introduced into Greece, 26
       ”     and Babylonians, 26;
          Chinese, 29, 114;
          Borneo, 26
     Goat, _see_ Capricorn
     Golius, 235
     Good Friday, 423-26
     Gravity, 100, 137, 160, 169, 191, 237, 445, 447, 482, 493
     Greek Astronomers and Astronomy, 27, 28, 36, 51 _et seq._, 112,
              159, 168, 171, 172, 176, 178, 200, 204, 433, 446, 463, 495
     Gruppe, _n._76
     Guelfs, 413
     Guido Bonatti, 213, 472
     Guido Cavalcanti, 416, 426
     Guido of Montefeltro, 213

     Hades, 54
     Hammurabi, 40
     Haroun al Raschid, 182
     He, and Ho, Chinese astronomers, 30
     Heath, _n._75-76
     Heaven, eighth, 366, 402, 475
        ”    fourth, 284
        ”    ninth, 233
        ”    seventh, 284, 455
        ”    third, 429, 483
        ”    of fire, 58 (_see also_ fire)
        ”    of Jupiter, 393
        ”    of Mars, 303, 313, 393
        ”    of Mercury, 332, 441
        ”    of the Moon, 392, 431, 447, 455, 484
        ”    of Saturn, 301, 393, 407
        ”    of Stars, 288, 304, 393
        ”    of the Sun, 240, 256, 272, 373, 381, 431
        ”    of Venus, 256, 393, 429, 435, 459, 483
     Heavens (_see also_ Star sphere), 58, 59, 67, 91, 209, 253,
                    254, 256, 262, 300, 393, 429, 431, 435, 484, 447
     ” influence of, 266
     ” revolution of, 9, 18, 20, 51, 57, 62, 63, 70, 74, 75, 82, 85,
                     88, 98, 102, 104, 108, 124, 136, 137, 185
                    (_see also_ Celestial motions)
     Hebrew cosmogony, 46, 57;
       year, 39
     Heinrich of Mainz, 343, 384
     Heliacal rising, 39, 40, 44, 45, 52, 191
     Hell, 205, 353, 358, 367 to 371, 390, 423
     Hemisphere, Southern, 286, 322, 329, 330, 334, 336,
                           339,  353, 407, 443, 447
     Henry VII., Emperor, 271
     Heracleides, 74, 75, 102, 109
     Hercules, Pillars of, 34, 54, 103, 205, 340, 344, 345
     Herodotus, 55
     Hesiod, 51, 52, 161
     Hesperus, 52
     Hicetas, 74, 75
     Hindu arithmetic, 182;
       astronomy, 181;
       calendar, 127;
       constellations, 30;
       cosmogony, 45;
       zodiac, 30
     Hindus and eclipses, 45
     Hipparchus, 50, 122 _et seq._, 138, 143, 153, 189,
                191, 193, 233, 240, 275, 287, 288, 432, 493
          ”     Star Catalogue of, 123, 144, _n._188
          ”     and Ptolemy, 133-5, 137, 143, 158
     Homer, 34, 51, 52, 72
     Horoscope, 173, 174, 201, 203, 216, 226
     Hose, Dr., 27
     Hours, Church, 347, 348;
           “Equal,” 27, 347, 356;
           “Temporary,” 27, 347, 356
     Hyades, 43, 44
     Hypatia, 163

     Imbriani, _n._227, _n._414
     India (_see also_ Hindu), 103, 111, 181, 339, 343
     Inferno, 283, 307, 367 _et seq._, 409-10
     ” and Brunetto Latini, 226
     ”  ”  Michael Scot, 214
     Instruments, astronomical, 13, 113, 133, 135, 182, 203, 218
     Intelligences, 249, 483
     Isaiah, 34, 175
     Isidore, 178, 243, 250

     Japanese, 38
     Jerusalem, 157, 333, 339, 340, 345, 360, 373,
                374, 388, 395, 397, 400, 401;
       centre of earth, 176, 341, 343, 344, 353, 369;
       latitude of, 387, 406
     Jews, 25, 213, 216;
       astrologer, 202;
       astronomers, 203, 421
     Job, 34
     Johannes Hispalensis, _n._235
     Jowett, _n._82
     Jubilee year (1300 A.D.), 415
     Julius Cæsar, 170, 175, 274
     Jupiter, 16, 120, 141, 145, 150, 169, 189,
                  310, 311, 407, 418, 451, 491
     ” colour, 17, 311, 467, 473, 477;
       dimensions, 488, 490
     ” period, 23, 69, 91, 109, 142, 436, 437
     ” and astrology, 174, 243, 468, 473, 476, 477
     Justinian, 300

     Kepler, _n._94
     King, L. W., _n._37
     Knobel, _n._30
     Kugler, _n._35

     Leo, 31, 43, 144, 155, 174, 290, 313, _n._399, 406,
                  407, 410, 411, 418, 420, 422, 423, 473, 476
     Lethe, 390
     Leucippus, 62, 63
     Libra, 31, 185, 265, 278, 325, 365, 378, 380, 388
       ”    and moon, 367, 379, 383, 384, 402, 406, 418
       ”    and sun, 278, 323, 382
     Lignières, De, Canons of, 202
     “Libros de Saber,” 195
     Lion, _see_ Leo
     Lionardo Bruni, 223, 225, 236, 413
     Livy, 238
     Lockyer, Sir Norman, 29, 155
     Lodestone (_see also_ magnet), 211, 291
     Longfellow, _n._393
     Longitude, 338, 339
     Lucifer, 371, 372
     Lubin, _n._236, _n._315
     Lucan, 238, 239, 324, _n._330
     Lucia (imaginary city), 323-27
       ”   the lady, 380

     Macrobius, 109
     Magnet (_see also_ lodestone), 211, 291, 292, 443, 451
     Mahaffy, _n._113
     Mahomedans, 39, 209, 216
     Malacoda, 370, _n._370, 410-12, 426
     Malaspina, 278, 279, 473
     Manfred, 242, 318, 376
     Manilius, 168
     Maps, 205, 343, 344, 384;
        climate maps, 247, 248;
        Greek maps, 247
     Marco Lombardo, 479
     Marco Polo, 293, 342
     Mars, 3, 16, 17, 23, 69, 90, 93, 109, 112, 118, 120, 138,
           150, 169, 173, 189, 248, 310, 321, 411, 418, 420,
           451, 467, 468, 476, 488, 490
       ”   colour of, 17;
           dimensions, 488
       ”   period, 436
       ”   occultation of, 105, 310, 433
       ”   sphere of, 477
       ”   and astrology, 174, 243, 473, 477
     Mathematics, 79, 81, 105, 107, 121, 135, 151, 184, 203
     Matilda, 453
     Maunder, E. W., 24 Note, 35, 127
     Mediterranean, 395, 398
     Mercury, 15, 16, 23, 69, 70, 91, 93, 109, 121, 142
              _et seq._, 144, 169, 189, 245, 249, 309
              _et seq._, 407, 418, 451, 467, 490
        ”    diameter, 236;
             dimensions, 458, 477, 488;
             period, 436
        ”    and astrology, 173
     Meridian, 22, 26, 280, 338, 346, 349, 361, 365, 368,
               371,387, 390, 394-7, _n._398, 439
     Meroe, 118
     Meteors, 61, 174, 239, 318, 319, 473, 476, 493;
         meteorites, 490
     Meteorology, 236
     Meton, 93, 145, 161, 162, 172, 177, 419
     Michael Scot, 213 _et seq._, 237, 306, 472
     Milky Way, _see_ Galaxy
     Milton, 66, 210, 420, 456
     Mimnermus, 53
     Montaperti, 242, 413
     Month, Babylonian, 41;
            Egyptian, 144;
            Roman, 253;
            Syrian, 253
       ”    defined, 22, 30
       ”   anomalistic, 23;
           intercalary, 38, 170;
           sidereal, 22, 30
       ”   names of, 171
       ”   synodic, 15, 20, 30, 52, 162, 163
       ”   and moon, 266, 350, 436
     Moon, 308, 402, 406, 407, 418, 419, 456, 469, 491
       ”   apogee of, 449
       ”   distance, 105, 108, 148 _et seq._, 150, 152, 160,
                     189 _et seq._, 488
       ”   dimensions of, 56, 114, 152 _et seq._, 160,
                          188 _et seq._
       ”   ecclesiastical, 419-422
       ”   eclipses, 55
       ”   epicycle, 449
       ”   god, 37
       ”   influence of, 237, 266, 450, 473, 489
       ”   inhabited, 71
       ”   mansions of, 30
       ”   markings on, 61, 231, 248, 266, 269, 392, 393,
                        462 _et seq._, 469, 476
       ”   movements of, 13, 14, 18, 29, 100, 105, 114, 117,
                         146 _et seq._, 219, 257, 264, 265,
                         339, 350, 383, 402 _et seq._
       ”   orbit, 256
       ”   perigee of, 448, 449
       ”   nodes of, 147
       ”   periods:—sidereal, 264, 436, 437;
                     synodic, 437
       ”   phases of, 14, _n._76, 191, 264, 266, 469, 476;
             full, 14, 264, 266, 367, 386, 371, 406, 410, 411, 419, 423;
             gibbous, 264, 266;
             half, 108, 446;
             new, 14, 29, 40, 52, 264
       ”   positions of, 402
       ”   rising, 14, 263, 266, 350
       ”      ”    in Purgatory, 363, 378-80, 389
       ”   setting, 14, 263, 265, 350, 367, 369
       ”      ”    in Purgatory, 380
       ”   sphere of, 169, 308, 449, 465, 477, 484, 487
       ”   substance, 55, 71, 114, 463 _et seq._, 494
       ”   waning, 262, 266, 380
       ”   worship of, 25
       ”   and astrology, 173, 174, 249, 268, 407,
                          419, 450, 472 _et seq._
       ”    ”  Dante, 261 _et seq._
       ”    ”  Mars, 310, 433
       ”    ”  month, 13, 14, 15, 28, 30, 38, 41, 52, 171
       ”    ”  sun, balancing, 265;
                    contrasted, 268
       ”    ”  tides, 189 _et seq._, 237, 445
       ”    ”  time, 266, 349, 367, 369, 370, 406, 419, 488
       ”    ”  zodiac, 265
     Moore, Dr. E., 236, _n._236, _n._237, 308, _n._326, _n._330,
                    334, _n._340, _n._380, 384, _n._411, _n._415,
                    419, 448, _n._452, _n._469, 471, _n._471
     Moors, 201, 203, 214
     Morning Star, 312, 314, 373, 410, 420, 421, 422, 470, 477
     Morocco, 340, 361
     Motion, Law of, 93, 100, 121, 159, 480
     Movers, _see_ First Mover, and Spheres
     Mulmul, 41
     Music of the Spheres, 67, 104

     Nabonassar, 144
     Naples, 240
     Nasir-ed-din, 195
     Nestorians, 181, 182, 209
     Nero, 171
     Newton, 100, 481
     Nineveh, 34, 44
     Night personified, 278
     Nino, 378, 416, 426
     Nile, 344
     Nones, 219, 348

     Observatories, Alexandria, 113, 116, 135;
       Baghdad, 182;
       Greenwich, 153;
       Pekin, 114;
       Persian, 195;
       The Cape, 153;
       of Eudoxus, 88;
       of Hipparchus, 122
     “Observatory, The,” _n._24, 34
     “On the Heavens,“ _see_ De Cælo
     Occultations, 105, 145
     Omons, 218
     Opposition, defined, 174, 119, 141
     Orion, 12, 36, 52, 155
     Orosius, 240, 341, 343, 384, 438
     Ottimo, 273, 418, _n._473
     Ovid, 168, 238, 239, 297, 305

     Padua, 227
     Paradise (_see also_ Eden), Earthly, 285, 295, 344, 345, 353,
              366, 373, 385, 390, _n._391, _n._399, 401, 482
     Paradise Lost, 210
     Parallax, 153, 191
     Paris, 158, 201, 204;
         University, 154, 228, 241, 242
     Parmenides, _n._76, 428
     Parsis, 127
     Pekin, 114, 116
     Pericles, _n._61
     Perigee, 23, 119, 148, 150, 448-51
     Persia, 209
     Petrarch, _n._332
     Phaëton, 303, 333
     “Phainomena,” of Aratus, 32, 35
     Philolaus, 70, 85, 431
     Philosophy, 255, 281, 314, 315, 346
     Phœnicians, 25, 56
     Phosphor, 68, 80
     Piccarda, 300
     Pietro d’ Abano, 342
     Pinches, T. C., 48
     Pisces (_see also_ Fishes), 32, 129, 138, 290, 295, 307, 309, 359,
            360, 368, 370, 373, _n._380, 383, 385, _n._399,
            403, 406, 407, 410, 411, 418, 420, 423, 494-95
     Planets, defined, 16, 45, 52, 58, 60, 63, 65, 68, 70, 79, 219, 254,
                       257, 269, 279, 289, 307 _et seq._, 312,
                       _n._399, 419, 461, 466, 468, 488, 494-95
        ”     aspects of, 200, 476
        ”     astrology and, 173-4, 211, 219, 243, 249, 405
        ”     distances of, 150, 189, 194
        ”     houses of, 174, 476, _n._473
        ”     influences of, 254, 472, 473, 474
        ”     movements of, 15, 16, 29, 44, 58, 68, 69, 70, 79, 80,
                            88-90, 104, 118, 123, 138, 159, 248, 312,
                            330, 331
        ”     names of, 80, 83
        ”     nature of, 461
        ”     periods of, 23, 29, 69, 83, 89, 91, 100, 109,
                          141, 219, 313, 436
        ”     positions of, 402 _et seq._, 419
        ”     shadows cast by, _n._280
        ”     varying velocity of, 94, _n._94
        ”     and the sciences, 312
     Plato, 80 _et seq._, 85, 91, 98, 101, 104, 159, 217, 238,
                            239, 313, 431, 444, 462, 479, 482, 483
     Pleiades, 28, 29, 35, 40, 52, 155
        ”     and Australian legend, 28
        ”      ”  Tahitan natives, 28
     Pliny, 50, 123, 170, 342
     Plunkett, Miss, 34
     Plutarch, 85, 107, 137, 463
     Pole, celestial, 12, 18, 51, 65, 105, 157, 185, 186, 187, 286,
                       287, 289, 297, 302, 323, 335, 434, 439, 477;
           north, 373;
           south, 286, 292, 293, 335, 373, 378, 489
       ”   terrestrial, 247, 322;
           north, 323, 370;
           south, 323
     Pole star, 9, 67, 127, 291, 323
     Popes, 276, 316;
       Boniface VIII., 415, 416;
       Gregory IX., 213;
       Honorarius II., 214;
       Urban IV., 318, 413
     Poseidonius, 134, 157, 170, 240
     Precession of Equinoxes, _see_ Equinox
     Prickard, _n._463
     Primum Mobile, 194, 204, 210, 299, _n._232, 291, 308, 313, 381,
                    400, 401, 432-434, 436, 440, 451, 455, 456, 477, 484
     Proclus, 170
     Proctor, R. A., _n.24_, 34, 35
     Procyon, 155, 187
     Ptolemy, 5, 24 _n.24 n._34, 134 _et seq._, 154,
              156, 160, 163, 170, 178, 182, 186, 202, 209, 210, 218,
              242, 245, 261, 275, 288, 290, 291, 305, 333, 350
        ”     Almagest,  113, 115, 123, 182, 184, 201
        ”   dimensions of earth, 182;
            of heavenly bodies, 191
        ”   geography of, 157, 205, 337, 341
        ”   quoted, 134
        ”   system of, 381, 431, 432, 491
        ”      ”    ”  epicycles, 256, 315
        ”   works by, 156, 157, 182
        ”    and  Apollonius, 118
        ”     ”   Aristarchus, 107
        ”     ”   Arabs, 147, 152, 183, 188, 192-4
        ”     ”   colure, 403
        ”     ”   Dante, 232, 235, 239, 459, 468
        ”     ”   eclipses, 338;
                    and ecliptic, 185
        ”     ”   Hipparchus, 126, 133, 143, 146
        ”     ”   moon, 146, 448, 449
        ”     ”   precession, 187, 193, 432
        ”     ”   Regulus, 406
        ”     ”   stars, 292, 294, 339
        ”     ”   Venus, 315
     Ptolemy Philadelphus, 144
        ”    Ptolemies, Royal, 113
     Purgatory, 105, 205, 295, 345, 360, 367, 370, 372, 373,
                390, 401, 407, 453, 454
         ”     gate of, 362, 380, 385, 453
         ”     latitude of, 286, 353, 387
         ”     Mountain of, 105, 262, 286, 295, 311, 312, 332-5, 353,
                            360 _et seq._, 373, 375, 378, 381, 382,
                            385, 386, 388, 390, 452, 453, 455
     Pyramids, 45, 81, 127
     Pythagoras, 66 _et seq._, 236, 238, 302, 431
     Pythagoreans, 62, 66 _et seq._, 75, _n._76, 79, 85, 88,
                   91, 96, 100, 101, 102, 104, 110, 111, 304, 490

     Quadrivium, 177
     ‘Quæstio de Aqua et Terra,’ 256, 258, 340, 444, 452

     Ram (_see_ Aries), 279
     Ravenna, _n._227, 273
     Regulus, 43, 144, 155, 187, 290, 406, 411, 420
     Retrograde Motion, 16
     Rhodes, 67, 122, 134, 158
     Rigel, 155
     Ristoro, 217, 241 _et seq._, 257, 268, 274, 292, 288, 300,
              328, 329, 444, _n._451, 464, _n._478
        ”   and comet, 318;
            constellations, 443, 451;
            eclipses, 317;
            ecliptic, 331;
            habitable earth, 446;
            meteors, 319
     Rizzacasa d’Orsogna, Prof., 400
     Rome, 111, 157, 241, 316, 319, 323, 345, 383, 385, 396, 415
       ”   Church of, influence on astronomy, 175, 178
       ”   Empire of, 262;
             influence on astronomy, 138, 167, 172, 178
     Rome, and calendar, 172, 175
     Rubruquis, Friar, 342

     Sacrobosco, 202, 249
     Sagittarius, 279, 281, 290, 380, 383, 385
     St. Bernard, 312, 354, 401
     St. John, 282, 317
     St. Louis, King, 342
     St. Paul, 32, 483
     St. Peter, 396, 468
     Salimbene, 212
     Saracens, 214
     Sardinia, 344, 364, 383, 384
     Saturn, 16, 23, 69, 91, 105, 109, 120, 141, 169, 189, 279, 281,
             311, 364, 389, 393, _n._398, 406, 407, 410, 411, 417,
             420, 422, 423, 450, 456, 468, 469, 490
        ”   dimensions, 488;
            movements, 311;
            period, 436
     Scales, _see_ Libra
     Scartazzini, 379, _n._455
     Schiaparelli, _n._35, _n._39, _n._236
     Schwary, 34
     Scipio, 168-69, 393;
       Dream of, 168, 237
     Scorpio, 30, 31, 43, 365, 378, 379, 380, 383, 384, 385,
              387, 405, 476, 489
     Seleucus, 110
     Seneca, 66, 169, 174, 237, 239, 342, 473;
       and meteors, 319
     Shakespear, 456
     Sheol, 46
     Sigieri, 228
     Simplicius, 90, 170
     Sirius, 39, 52, 67, 115, 155, 187
     Socrates, 82, 83, 239
     Solstice, definition of, 11, 26, 29, 107, 117, 127, 185, 277, 394
     Sordello, 378, 382
     Sosigines, 171
     Southern Cross, 12, 156, 294
     Spain, 339-42, 388
     Spheres, 9, 57, 58, 62, 65, 68, 83, 84, 104, 137, 169, 184, 187,
              204, 219, 249, 254, 257, 262, 302, 358, 392, 393,
              _n._399, 429 _et seq._, 444, 452, 457,
              473, 478, 418
        ”   crystalline, 433
        ”   eighth sphere, 466
        ”   elevating power of, 443
        ”   homocentric, 112
        ”   influence of, 239, 249, 254, 478, 479, 485, 488, 494
        ”   movement of, 395, 400, 453
        ”   movers of, 106, 159, 204, 254, 400, 482, 483, 484, 496
        ”   music of, 67, 68, 104, 169, 302, 392, 455, 456
        ”   ninth, 432-3
        ”   sky as a, 51
        ”   substance of, 95, 104, 193, 433, 461
        ”   ‘unrolling,’ 95, 102, 106
        ”   of air, 442, 452
        ”   of Eudoxus, 88, 89, 94, 106, 107, 112
        ”   of fire, 103, 159, 308, 392, 442, 453, 455, 490
        ”   of moon, 103, 308, 477
        ”   of sun, 88, 93, 253
        ”   of stars, 13, 67, 70, 72, 89, 94, 95, 96, 109, 129, 137,
                      152, 160, 187, 253, 313, 356, 433, 437, 438,
                      456, 476, 477
        ”   of water, 442, 443
        ”   and Arabs, 194
        ”    ”  Roger Bacon, 118, 202
        ”    ”  time, 401
     Spica, 124-6, 130, 155
     Stars, 219, 283 _et seq._, 489, 402, 493-94
       ”   brightness of, 123, 154, 187
       ”   catalogues, 123, 133, 144, 154, 187, 288;
             Abu Hazan’s, 184;
             Hipparchus’, 188;
             Ptolemy’s, 187
       ”   Dante’s ‘quindici stelle,’ 155
       ”   dimensions of, 190, 488
       ”   globes, 115
       ”   distance of, 17, 108, 153, _n._190, 488, 492-93
       ”   influence of, 211, 254, 256, 443, 450, 473, 475,
                         478, 479, 488
       ”   magnitudes of, 154, 187, 188, 234, 289, 299, 488;
             first-magnitude, 154, 187
       ”   movements of, 9, 51, 52, 83, 84, 86, 97, 136, 187, 284, 286,
                         287, 289, 301, 354, 424, 495, 496
       ”   new, 123
       ”   number of, 123, 187, 288, 477, 495
       ”   Pole, 291, 299
       ”   positions of, 42, 123, 126, 193
       ”   shooting, 103, 185, 262, 301, 319, 487, 490
       ”   southern, 283, 293, 373, 378, 489
       ”   substance of, 103, 104, 136
       ”   worship of, 37, 38, 51
       ”   and human souls, 86
       ”    ”  Milky Way, 103
       ”    ”  time, 257, 285, 289, 367, 488
     Stationary points, 16, 44, 121
     Statius, 385-7, 453
     Stilbon, 80
     Stoics, 112, 134, 463
     Stobæus, 107
     Stonehenge, 29
     Strabo, 170, 240
     Styx, 54
     Sumerians, 36, 38;
       year, 38
     Sun, boat of, 45, 46
      ”   brightness of, 270, 282, 462, 477, 488, 469
      ”   centre of universe, 101, 110
      ”   dimensions of, 56, 110, 146, 153, 188, 457-8, 469, 488, 491
      ”   distance of, 108, 146, 153, 189, 193, 457-8
      ”   door of, 46
      ”   god, 37, 48, 54
      ”   heaven of, _see_ Heavens
      ”   Lake of, 54
      ”   movements of, 10, 13, 39, 53, 55, 62, 115, 116, 120, 145, 146,
                        185, 187, 247, 256, 272-4, 276, 322 _et seq._,
                        338, 346, 349, 390-2, 402, 403
      ”   perigee of, 448
      ”   period of, 436
      ”   positions of, during Vision, 402 _et seq._
      ”   rise, 10, 13, 14, 25, 28, 54, 267, 270, 271, 273, 339, 346,
                348, 356, _n._356, 406
      ”   rise in Forest, 354, 358, 367, 369
      ”    ”   in Purgatory, 271, 360, 362, 363, 364, 366,
                             374, 385, 389, 406
      ”   set, 10, 13, 14, 48, 253, 262, 271, 273, 279, 280, 282, 294,
               339, _n._336, 350, 356, 383, 385
      ”    ”  in Purgatory, 271, 361, 363 to 366, 378, 382, 388
      ”   source of all light, 470, 477, 488
      ”   worship of, 25, 37, 45
      ”   and astrology, 173, 473, 477
      ”    ”  comets, 103
      ”    ”  Dante, 267, 270 _et seq._
      ”    ”  stars, 254, 470, 477
      ”    ”  time, 219, 254, 257, 349, 367, 372, 488
     Sundial, 27, 115, 158, 182, 192, 219
     Syene, 117, 156
     Sylvester II., 203
     Synodic revolution, 22, 30
     ‘Syntaxis’ (_see_ Almagest), _n._125,
                136, 157, 182, 193, 209

     Tabit ben Korrah, 194
     Tables:—
       ”   Alfonsine, 195, 202, 203, 242, 275, 341;
           astronomical, 203, 242, 245;
           Greek, 117;
           Hakemite, 183;
           Toledo, 184, _n._202, 421
       ”   of constellations, 31, 154;
           Days of the Vision, and positions of sun, etc., 425;
           Ptolemy’s first-magnitude stars, 155;
           planetary distances and dimensions, 189;
           positions of sun and moon, 190;
           planetary periods, 91, 436;
           planets in zodiac, 325;
           revolutions of sun, moon, and planets, 22, 23;
           time references in the Divine Comedy, 358-66
     Tartarus, 54
     Taurus, _n._35, 43, _n._43, 144, 148, 149,
             365, 387, 399, 403, 410, 422
     “Tesoretto,” 226, 242
     “Tetrabiblios,” 156, 233, 234
     Thales, 50, 55 _et seq._, 60, 61, _n._76, 98, 238, 239, 297
     Theon of Alexandria, 163
     Theon of Smyrna, 135, 144
     Tides, 134, 257, 445
     Tierce, 220, 347, 348, 372
     Timæus, 82, 101, 238
     Time, measurement of, 25, 47, 84, 86, 161, 162, 170, 186
     Thule, 157
     Timocharis, 124, 125, 144
     Toledo, 202, 213
       ”     tables of, 184, _n._202, 421
     Toynbee, Paget, _n._225, _n._236, _n._241, _n._417,
                     _n._437, _n._464
     Tozer, H. F., _n._476
     Trepidation, 194, _n._232-3
     “Trèsor, Li Louvres dou,” 218, 226, 243
     Trigonometry, spherical, 113, 123, 153, 183;
       invention of, 133
     Trivium and Quadrivium, 177, 261, 312
     Twins, _see also_ Gemini, 279, 400
     Tycho Brahè, 120

     Ulysses, 51, 52, 292, 335, 340, 370, 395
     Universe (_see_ Cosmogonies), 97;
       dimensions, 390, 459;
       of Dante, 257, 258, 353 _et seq._, 489
     Universities, Bologna, 199, 216, 226, 227, 241, 478;
       mediæval, 199 _et seq._;
       Naples 240;
       Padua, 227;
       Paris, 199, 213, 228, 241;
       Oxford, 199, 213;
       Rome, 241
     Ur, 37
     Urban IV., 201
     Ursa, Major, (_see also_ Bear, and Wain), 234,
                  295 _et seq._, 322, 368
       ”   Minor, 234, 297, _n._299

     Varaha Mihira, _n._111
     Vega, 155, 187
     Venturi, 453
     Venus, 3, 15, 17, 23, 69, 80, 90, 93, 109, 112, 121, 144, 150, 169,
            279, 281, 286, 300, 307, 309, 314, 373, 389, _n._399,
            406-11, 418-25, 481-66
       ”   dimensions, 488
       ”   distance, 458 _et seq._
       ”   goddess of, 38
       ”   movements of, 314, 315, 435, 477
       ”   movers of, 483
       ”   phases of, 492
       ”   period of, 314, 315, 436
       ”   and astrology, 173, 189, 472, 477
       ”   as evening star, 52, 142
       ”   as morning star, 15, 52, 64, 68, 142
     Verona, 226, 256, 444
     Vespers, 219, 348
     Villani, 213, 223, 226, 319
     Virgil, 167, 168, 239, 271, 328, 374, 381, 441
       ”    quoted, 173, 279
       ”    works of, 238
       ”    as guide, 286, 354, 367, 371, 387, 409, 481
       ”    and sun, 271, 333, 381, 392
     Virgin, Virgo, 12, 32, 124, 141, 144, 290, 384, 418
     Vision, date of Dante’s, 357, 407 _et seq._;
             duration of 354-7, 401
     ‘Vita Nuova,’ 253, 257, 411, 432

     Wain, The (_see also_ Bear), 293, 295, 359, 368, 373
     Wellhausen, _n._39
     Wicksteed, P. H., _n._277, 306, 447
     World-soul, 98, 159

     Xenophanes, 98

     Yaou, Emperor, 29;
       Canon of, 38
     Year, 253;
          definition of, 23
       ”   Arab, 39;
           Babylonian, 40, 128, 161;
           Chinese, 38;
           Egyptian, 39, 45;
           Hebrew, 39;
           Greek, 161, 162, _n._172;
           Mahomedan, 39;
           Persian, 313;
           Roman, 170;
           Sumerian, 38
       ”   civil, 22;
           luni-solar, 38, 39, 93;
           lunar, 39;
           sidereal, 22, 128;
           solar, 22, 56, 128, 163;
           tropical, 22, 129, 161, 162, 171, 193, 274, 275
       ”   leap, 171, 276
       ”   length of, 187, 274
       ”   and Hipparchus, 128, 135

     Ziggurat, 37
     Zodiac, 10, 13, 14, 15, 16, 18, 23, 28, 30, 31, 43, _n._43,
             69, 119, 143, 185, 265, 272, 278, 280, 289, 300, 309, 311,
             333, 349, 382, 384, 402, 405, 448, 470, 488
        ”   age of, 34
        ”   Chinese and Hindu, 29, 30
        ”   constellations of, 31, 42, 43, 47, 129, 219, 248,
                               290, 356, 368, 402, 476
        ”   lunar, 30
        ”   signs of, 129, 174, 185, 186, 245, 329,
                      356, 368, 379, 383, 402
        ”   sun in, 276, 282
        ”   and months, 276, 281, 282
     Zodiacal revolutions, 23
     Zoroaster, 218