Produced by D. R. Thompson





ON THE METHOD OF ZADIG

ESSAY #1 FROM "SCIENCE AND HEBREW TRADITION"

By Thomas Henry Huxley




RETROSPECTIVE PROPHECY AS A FUNCTION OF SCIENCE

"Une marque plus sure que toutes celles de Zadig." [1]--Cuvier.


It is an usual and a commendable practice to preface the discussion of
the views of a philosophic thinker by some account of the man and of the
circumstances which shaped his life and coloured his way of looking at
things; but, though Zadig is cited in one of the most important chapters
of Cuvier's greatest work, little is known about him, and that little
might perhaps be better authenticated than it is.

It is said that he lived at Babylon in the time of King Moabdar; but
the name of Moabdar does not appear in the list of Babylonian sovereigns
brought to light by the patience and the industry of the decipherers of
cuneiform inscriptions in these later years; nor indeed am I aware
that there is any other authority for his existence than that of
the biographer of Zadig, one Arouet de Voltaire, among whose more
conspicuous merits strict historical accuracy is perhaps hardly to be
reckoned.

Happily Zadig is in the position of a great many other philosophers.
What he was like when he was in the flesh, indeed whether he existed at
all, are matters of no great consequence. What we care about in a light
is that it shows the way, not whether it is lamp or candle, tallow or
wax. Our only real interest in Zadig lies in the conceptions of which he
is the putative father; and his biographer has stated these with so much
clearness and vivacious illustration, that we need hardly feel a pang,
even if critical research should prove King Moabdar and all the rest of
the story to be unhistorical, and reduce Zadig himself to the shadowy
condition of a solar myth.

Voltaire tells us that, disenchanted with life by sundry domestic
misadventures, Zadig withdrew from the turmoil of Babylon to a secluded
retreat on the banks of the Euphrates, where he beguiled his solitude
by the study of nature. The manifold wonders of the world of life had
a particular attraction for the lonely student; incessant and patient
observation of the plants and animals about him sharpened his naturally
good powers of observation and of reasoning; until, at length, he
acquired a sagacity which enabled him to perceive endless minute
differences among objects which, to the untutored eye, appeared
absolutely alike.

It might have been expected that this enlargement of the powers of the
mind and of its store of natural knowledge could tend to nothing but
the increase of a man's own welfare and the good of his fellow-men. But
Zadig was fated to experience the vanity of such expectations.


  "One day, walking near a little wood, he saw, hastening that
  way, one of the Queen's chief eunuchs, followed by a troop of
  officials, who appeared to be in the greatest anxiety, running
  hither and thither like men distraught, in search of some
  lost treasure.

  "'Young man,' cried the eunuch, 'have you seen the Queen's dog?'
  Zadig answered modestly, 'A bitch, I think, not a dog.'
  'Quite right,' replied the eunuch; and Zadig continued, 'A very
  small spaniel who has lately had puppies; she limps with the
  left foreleg, and has very long ears.' 'Ah! you have seen her
  then,' said the breathless eunuch. 'No,' answered Zadig, 'I have
  not seen her; and I really was not aware that the Queen
  possessed a spaniel.'

  "By an odd coincidence, at the very same time, the handsomest
  horse in the King's stables broke away from his groom in the
  Babylonian plain. The grand huntsman and all his staff were
  seeking the horse with as much anxiety as the eunuch and his
  people the spaniel; and the grand huntsman asked Zadig if he had
  not seen the King's horse go that way.

  "'A first-rate galloper, small-hoofed, five feet high;
  tail three feet and a half long; cheek pieces of the bit of
  twenty-three carat gold; shoes silver?' said Zadig.

  "'Which way did he go? Where is he?' cried the grand huntsman.

  "'I have not seen anything of the horse, and I never heard of
  him before,' replied Zadig.

  "The grand huntsman and the chief eunuch made sure that Zadig
  had stolen both the King's horse and the Queen's spaniel, so
  they haled him before the High Court of Desterham, which at once
  condemned him to the knout, and transportation for life to
  Siberia. But the sentence was hardly pronounced when the lost
  horse and spaniel were found. So the judges were under the
  painful necessity of reconsidering their decision: but they
  fined Zadig four hundred ounces of gold for saying he had seen
  that which he had not seen.

  "The first thing was to pay the fine; afterwards Zadig was
  permitted to open his defence to the court, which he did in the
  following terms:

  "'Stars of justice, abysses of knowledge, mirrors of truth,
  whose gravity is as that of lead, whose inflexibility is as that
  of iron, who rival the diamond in clearness, and possess no
  little affinity with gold; since I am permitted to address your
  august assembly, I swear by Ormuzd that I have never seen the
  respectable lady dog of the Queen, nor beheld the sacrosanct
  horse of the King of Kings.

  "'This is what happened. I was taking a walk towards the little
  wood near which I subsequently had the honour to meet the
  venerable chief eunuch and the most illustrious grand huntsman.
  I noticed the track of an animal in the sand, and it was easy to
  see that it was that of a small dog. Long faint streaks upon the
  little elevations of sand between the footmarks convinced me
  that it was a she dog with pendent dugs, showing that she must
  have had puppies not many days since. Other scrapings of the
  sand, which always lay close to the marks of the forepaws,
  indicated that she had very long ears; and, as the imprint of
  one foot was always fainter than those of the other three, I
  judged that the lady dog of our august Queen was, if I may
  venture to say so, a little lame.

  "'With respect to the horse of the King of Kings, permit me to
  observe that, wandering through the paths which traverse the
  wood, I noticed the marks of horse-shoes. They were all
  equidistant. "Ah!" said I, "this is a famous galloper." In a
  narrow alley, only seven feet wide, the dust upon the trunks of
  the trees was a little disturbed at three feet and a half from
  the middle of the path. "This horse," said I to myself, "had a
  tail three feet and a half long, and, lashing it from one side
  to the other, he has swept away the dust." Branches of the trees
  met overhead at the height of five feet, and under them I saw
  newly fallen leaves; so I knew that the horse had brushed some
  of the branches, and was therefore five feet high. As to his
  bit, it must have been made of twenty-three carat gold, for he
  had rubbed it against a stone, which turned out to be a
  touchstone, with the properties of which I am familiar by
  experiment. Lastly, by the marks which his shoes left upon
  pebbles of another kind, I was led to think that his shoes were
  of fine silver.'

  "All the judges admired Zadig's profound and subtle discernment;
  and the fame of it reached even the King and the Queen. From the
  ante-rooms to the presence-chamber, Zadig's name was in
  everybody's mouth; and, although many of the magi were of
  opinion that he ought to be burnt as a sorcerer, the King
  commanded that the four hundred ounces of gold which he had been
  fined should be restored to him. So the officers of the court
  went in state with the four hundred ounces; only they retained
  three hundred and ninety-eight for legal expenses, and their
  servants expected fees."

  Those who are interested in learning more of the fateful history
  of Zadig must turn to the original; we are dealing with him only
  as a philosopher, and this brief excerpt suffices for the
  exemplification of the nature of his conclusions and of the
  methods by which he arrived at them.


These conclusions may be said to be of the nature of retrospective
prophecies; though it is perhaps a little hazardous to employ
phraseology which perilously suggests a contradiction in terms--the
word "prophecy" being so constantly, in ordinary use, restricted to
"foretelling." Strictly, however, the term prophecy applies as much
to outspeaking as to foretelling; and, even in the restricted sense of
"divination," it is obvious that the essence of the prophetic operation
does not lie in its backward or forward relation to the course of time,
but in the fact that it is the apprehension of that which lies out of
the sphere of immediate knowledge; the seeing of that which, to the
natural sense of the seer, is invisible.

The foreteller asserts that, at some future time, a properly situated
observer will witness certain events; the clairvoyant declares that, at
this present time, certain things are to be witnessed a thousand miles
away; the retrospective prophet (would that there were such a word as
"backteller!") affirms that, so many hours or years ago, such and such
things were to be seen. In all these cases, it is only the relation
to time which alters--the process of divination beyond the limits of
possible direct knowledge remains the same.

No doubt it was their instinctive recognition of the analogy between
Zadig's results and those obtained by authorised inspiration which
inspired the Babylonian magi with the desire to burn the philosopher.
Zadig admitted that he had never either seen or heard of the horse of
the king or of the spaniel of the queen; and yet he ventured to assert
in the most positive manner that animals answering to their description
did actually exist and ran about the plains of Babylon. If his method
was good for the divination of the course of events ten hours old, why
should it not be good for those of ten years or ten centuries past;
nay, might it not extend ten thousand years and justify the impious in
meddling with the traditions of Oannes and the fish, and all the sacred
foundations of Babylonian cosmogony?

But this was not the worst. There was another consideration which
obviously dictated to the more thoughtful of the magi the propriety of
burning Zadig out of hand. His defence was worse than his offence. It
showed that his mode of divination was fraught with danger to magianism
in general. Swollen with the pride of human reason, he had ignored the
established canons of magian lore; and, trusting to what after all was
mere carnal common sense, he professed to lead men to a deeper insight
into nature than magian wisdom, with all its lofty antagonism to
everything common, had ever reached. What, in fact, lay at the
foundation of all Zadig's argument but the coarse commonplace
assumption, upon which every act of our daily lives is based, that we
may conclude from an effect to the pre-existence of a cause competent to
produce that effect?

The tracks were exactly like those which dogs and horses leave;
therefore they were the effects of such animals as causes. The marks at
the sides of the fore-prints of the dog track were exactly such as would
be produced by long trailing ears; therefore the dog's long ears were
the causes of these marks--and so on. Nothing can be more hopelessly
vulgar, more unlike the majestic development of a system of grandly
unintelligible conclusions from sublimely inconceivable premisses such
as delights the magian heart. In fact, Zadig's method was nothing
but the method of all mankind. Retrospective prophecies, far more
astonishing for their minute accuracy than those of Zadig, are familiar
to those who have watched the daily life of nomadic people.

From freshly broken twigs, crushed leaves, disturbed pebbles, and
imprints hardly discernible by the untrained eye, such graduates in the
University of Nature will divine, not only the fact that a party has
passed that way, but its strength, its composition, the course it took,
and the number of hours or days which have elapsed since it passed.
But they are able to do this because, like Zadig, they perceive endless
minute differences where untrained eyes discern nothing; and because
the unconscious logic of common sense compels them to account for these
effects by the causes which they know to be competent to produce them.

And such mere methodised savagery was to discover the hidden things
of nature better than _a priori_ deductions from the nature of
Ormuzd--perhaps to give a history of the past, in which Oannes would be
altogether ignored! Decidedly it were better to burn this man at once.

If instinct, or an unwonted use of reason, led Moabdar's magi to this
conclusion two or three thousand years ago, all that can be said is
that subsequent history has fully justified them. For the rigorous
application of Zadig's logic to the results of accurate and
long-continued observation has founded all those sciences which
have been termed historical or palaetiological, because they are
retrospectively prophetic and strive towards the reconstruction in human
imagination of events which have vanished and ceased to be.

History, in the ordinary acceptation of the word, is based upon the
interpretation of documentary evidence; and documents would have no
evidential value unless historians were justified in their assumption
that they have come into existence by the operation of causes similar to
those of which documents are, in our present experience, the effects. If
a written history can be produced otherwise than by human agency, or if
the man who wrote a given document was actuated by other than ordinary
human motives, such documents are of no more evidential value than so
many arabesques.

Archaeology, which takes up the thread of history beyond the point at
which documentary evidence fails us, could have no existence, except
for our well grounded confidence that monuments and works of art or
artifice, have never been produced by causes different in kind from
those to which they now owe their origin. And geology, which traces back
the course of history beyond the limits of archaeology, could tell us
nothing except for the assumption that, millions of years ago, water,
heat, gravitation, friction, animal and vegetable life, caused effects
of the same kind as they now cause. Nay, even physical astronomy, in
so far as it takes us back to the uttermost point of time which
palaetiological science can reach, is founded upon the same assumption.
If the law of gravitation ever failed to be true, even to a small
extent, for that period, the calculations of the astronomer have no
application.

The power of prediction, of prospective prophecy, is that which is
commonly regarded as the great prerogative of physical science. And
truly it is a wonderful fact that one can go into a shop and buy for
a small price a book, the "Nautical Almanac," which will foretell the
exact position to be occupied by one of Jupiter's moons six months
hence; nay, more, that, if it were worth while, the Astronomer-Royal
could furnish us with as infallible a prediction applicable to 1980 or
2980.

But astronomy is not less remarkable for its power of retrospective
prophecy.

Thales, oldest of Greek philosophers, the dates of whose birth and
death are uncertain, but who flourished about 600 B.C., is said to have
foretold an eclipse of the sun which took place in his time during a
battle between the Medes and the Lydians. Sir George Airy has written a
very learned and interesting memoir [2] in which he proves that such an
eclipse was visible in Lydia on the afternoon of the 28th of May in the
year 585 B.C.

No one doubts that, on the day and at the hour mentioned by the
Astronomer-Royal, the people of Lydia saw the face of the sun totally
obscured. But, though we implicitly believe this retrospective prophecy,
it is incapable of verification. In the total absence of historical
records, it is impossible even to conceive any means of ascertaining
directly whether the eclipse of Thales happened or not. All that can be
said is, that the prospective prophecies of the astronomer are always
verified; and that, inasmuch as his retrospective prophecies are the
result of following backwards, the very same method as that which
invariably leads to verified results, when it is worked forwards, there
is as much reason for placing full confidence in the one as in the
other. Retrospective prophecy is therefore a legitimate function of
astronomical science; and if it is legitimate for one science it
is legitimate for all; the fundamental axiom on which it rests, the
constancy of the order of nature, being the common foundation of all
scientific thought. Indeed, if there can be grades in legitimacy,
certain branches of science have the advantage over astronomy, in so
far as their retrospective prophecies are not only susceptible of
verification, but are sometimes strikingly verified.

Such a science exists in that application of the principles of biology
to the interpretation of the animal and vegetable remains imbedded
in the rocks which compose the surface of the globe, which is called
Palaeontology.

At no very distant time, the question whether these so-called "fossils,"
were really the remains of animals and plants was hotly disputed. Very
learned persons maintained that they were nothing of the kind, but a
sort of concretion, or crystallisation, which had taken place within the
stone in which they are found; and which simulated the forms of animal
and vegetable life, just as frost on a window-pane imitates vegetation.
At the present day, it would probably be impossible to find any sane
advocate of this opinion; and the fact is rather surprising, that
among the people from whom the circle-squarers, perpetual-motioners,
flat-earthed men and the like, are recruited, to say nothing of
table-turners and spirit-rappers, somebody has not perceived the easy
avenue to nonsensical notoriety open to any one who will take up the
good old doctrine, that fossils are all _lusus naturae._

The position would be impregnable, inasmuch as it is quite impossible
to prove the contrary. If a man choose to maintain that a fossil
oyster shell, in spite of its correspondence, down to every minutest
particular, with that of an oyster fresh taken out of the sea, was never
tenanted by a living oyster, but is a mineral concretion, there is no
demonstrating his error. All that can be done is to show him that, by a
parity of reasoning, he is bound to admit that a heap of oyster shells
outside a fishmonger's door may also be "sports of nature," and that
a mutton bone in a dust-bin may have had the like origin. And when you
cannot prove that people are wrong, but only that they are absurd, the
best course is to let them alone.

The whole fabric of palaeontology, in fact, falls to the ground unless
we admit the validity of Zadig's great principle, that like effects
imply like causes, and that the process of reasoning from a shell, or
a tooth, or a bone, to the nature of the animal to which it belonged,
rests absolutely on the assumption that the likeness of this shell,
or tooth, or bone, to that of some animal with which we are already
acquainted, is such that we are justified in inferring a corresponding
degree of likeness in the rest of the two organisms. It is on this
very simple principle, and not upon imaginary laws of physiological
correlation, about which, in most cases, we know nothing whatever, that
the so-called restorations of the palaeontologist are based.

Abundant illustrations of this truth will occur to every one who is
familiar with palaeontology; none is more suitable than the case of the
so-called _Belemnites._ In the early days of the study of fossils,
this name was given to certain elongated stony bodies, ending at one
extremity in a conical point, and truncated at the other, which were
commonly reputed to be thunderbolts, and as such to have descended from
the sky. They are common enough in some parts of England; and, in the
condition in which they are ordinarily found, it might be difficult to
give satisfactory reasons for denying them to be merely mineral bodies.

They appear, in fact, to consist of nothing but concentric layers
of carbonate of lime, disposed in subcrystalline fibres, or prisms,
perpendicular to the layers. Among a great number of specimens of these
Belemnites, however, it was soon observed that some showed a conical
cavity at the blunt end; and, in still better preserved specimens, this
cavity appeared to be divided into chambers by delicate saucer-shaped
partitions, situated at regular intervals one above the other. Now there
is no mineral body which presents any structure comparable to this, and
the conclusion suggested itself that the Belemnites must be the effects
of causes other than those which are at work in inorganic nature. On
close examination, the saucer-shaped partitions were proved to be all
perforated at one point, and the perforations being situated exactly
in the same line, the chambers were seen to be traversed by a canal, or
_siphuncle,_ which thus connected the smallest or aphical chamber with
the largest. There is nothing like this in the vegetable world; but an
exactly corresponding structure is met with in the shells of two kinds
of existing animals, the pearly _Nautilus_ and the _Spirula,_ and
only in them. These animals belong to the same division--the
_Cephalopoda--_as the cuttle-fish, the squid, and the octopus. But they
are the only existing members of the group which possess chambered,
siphunculated shells; and it is utterly impossible to trace any
physiological connection between the very peculiar structural characters
of a cephalopod and the presence of a chambered shell. In fact, the
squid has, instead of any such shell, a horny "pen," the cuttlefish has
the so-called "cuttle-bone," and the octopus has no shell, or, at most,
a mere rudiment of one.

Nevertheless, seeing that there is nothing in nature at all like the
chambered shell of the Belemnite, except the shells of the _Nautilus_
and of the _Spirula,_ it was legitimate to prophesy that the animal
from which the fossil proceeded must have belonged to the group of the
_Cephalopoda._ _Nautilus_ and _Spirula_ are both very rare animals, but
the progress of investigation brought to light the singular fact, that,
though each has the characteristic cephalopodous organisation, it is
very different from the other. The shell of _Nautilus_ is external,
that of _Spirula_ internal; _Nautilus_ has four gills, _Spirula_ two;
_Nautilus_ has multitudinous tentacles, _Spirula_ has only ten arms
beset with horny-rimmed suckers; _Spirula,_ like the squids and
cuttle-fishes, which it closely resembles, has a bag of ink which it
squirts out to cover its retreat when alarmed; _Nautilus_ has none.

No amount of physiological reasoning could enable any one to say whether
the animal which fabricated the Belemnite was more like _Nautilus,_ or
more like _Spirula._ But the accidental discovery of Belemnites in due
connection with black elongated masses which were: certainly fossilised
ink-bags, inasmuch as the ink could be ground up and used for painting
as well as if it were recent sepia, settled the question; and it became
perfectly safe to prophesy that the creature which fabricated the
Belemnite was a two-gilled cephalopod with suckers on its arms, and with
all the other essential features of our living squids, cuttle-fishes,
and _Spirulae._ The palaeontologist was, by this time, able to speak as
confidently about the animal of the Belemnite, as Zadig was respecting
the queen's spaniel. He could give a very fair description of its
external appearance, and even enter pretty fully into the details of its
internal organisation, and yet could declare that neither he, nor any
one else, had ever seen one. And as the queen's spaniel was found, so
happily has the animal of the Belemnite; a few exceptionally
preserved specimens have been discovered, which completely verify the
retrospective prophecy of those who interpreted the facts of the case by
due application of the method of Zadig.

These Belemnites flourished in prodigious abundance in the seas of the
mesozoic, or secondary, age of the world's geological history; but no
trace of them has been found in any of the tertiary deposits, and they
appear to have died out towards the close of the mesozoic epoch. The
method of Zadig, therefore, applies in full force to the events of a
period which is immeasurably remote, which long preceded the origin
of the most conspicuous mountain masses of the present world, and the
deposition, at the bottom of the ocean, of the rocks which form the
greater part of the soil of our present continents. The Euphrates
itself, at the mouth of which Oannes landed, is a thing of yesterday
compared with a Belemnite; and even the liberal chronology of magian
cosmogony fixes the beginning of the world only at a time when other
applications of Zadig's method afford convincing evidence that, could
we have been there to see, things would have looked very much as they do
now. Truly the magi were wise in their generation; they foresaw rightly
that this pestilent application of the principles of common sense,
inaugurated by Zadig, would be their ruin.

But it may be said that the method of Zadig, which is simple reasoning
from analogy, does not account for the most striking feats of modern
palaeontology--the reconstruction of entire animals from a tooth or
perhaps a fragment of a bone; and it may be justly urged that Cuvier,
the great master of this kind of investigation, gave a very different
account of the process which yielded such remarkable results.

Cuvier is not the first man of ability who has failed to make his own
mental processes clear to himself, and he will not be the last. The
matter can be easily tested. Search the eight volumes of the "Recherches
sur les Ossemens Fossiles" from cover to cover, and nothing but the
application of the method of Zadig will be found in the arguments by
which a fragment of a skeleton is made to reveal the characters of the
animal to which it belonged.

There is one well-known case which may represent all. It is an excellent
illustration of Cuvier's sagacity, and he evidently takes some pride
in telling his story about it. A split slab of stone arrived from the
quarries of Montmartre, the two halves of which contained the greater
part of the skeleton of a small animal. On careful examinations of
the characters of the teeth and of the lower jaw, which happened to be
exposed, Cuvier assured himself that they presented such a very close
resemblance to the corresponding parts in the living opossums that he at
once assigned the fossil to that genus.

Now the opossums are unlike most mammals in that they possess two bones
attached to the fore part of the pelvis, which are commonly called
"marsupial bones." The name is a misnomer, originally conferred because
it was thought that these bones have something to do with the support of
the pouch, or marsupium, with which some, but not all, of the opossums
are provided. As a matter of fact, they have nothing to do with the
support of the pouch, and they exist as much in those opossums which
have no pouches as in those which possess them. In truth, no one knows
what the use of these bones may be, nor has any valid theory of their
physiological import yet been suggested. And if we have no knowledge of
the physiological importance of the bones themselves, it is obviously
absurd to pretend that we are able to give physiological reasons why the
presence of these bones is associated with certain peculiarities of
the teeth and of the jaws. If any one knows why four molar teeth and an
inflected angle of the jaw are very generally found along with marsupial
bones, he has not yet communicated that knowledge to the world.

If, however, Zadig was right in concluding from the likeness of the
hoof-prints which he observed to be a horse's that the creature which
made them had a tail like that of a horse, Cuvier, seeing that the teeth
and jaw of his fossil were just like those of an opossum, had the same
right to conclude that the pelvis would also be like an opossum's; and
so strong was his conviction that this retrospective prophecy, about
an animal which he had never seen before, and which had been dead and
buried for millions of years, would be verified, that he went to work
upon the slab which contained the pelvis in confident expectation of
finding and laying bare the "marsupial bones," to the satisfaction of
some persons whom he had invited to witness their disinterment. As he
says:--"Cette operation se fit en presence de quelques personnes a
qui j'en avais annonce d'avance le resultat, dans l'intention de leur
prouver par le fait la justice de nos theories zoologiques; puisque le
vrai cachet d'une theorie est sans contredit la faculte qu'elle donne de
prevoir les phenomenes."

In the "Ossemens Fossiles" Cuvier leaves his paper just as it first
appeared in the "Annales du Museum," as "a curious monument of the force
of zoological laws and of the use which may be made of them."

Zoological laws truly, but not physiological laws. If one sees a live
dog's head, it is extremely probable that a dog's tail is not far off,
though nobody can say why that sort of head and that sort of tail go
together; what physiological connection there is between the two. So, in
the case of the Montmartre fossil, Cuvier, finding a thorough opossum's
head, concluded that the pelvis also would be like an opossum's. But,
most assuredly, the most advanced physiologist of the present day could
throw no light on the question why these are associated, nor could
pretend to affirm that the existence of the one is necessarily connected
with that of the other. In fact, had it so happened that the pelvis of
the fossil had been originally exposed, while the head lay hidden, the
presence of the "marsupial bones," though very like an opossum's, would
by no means have warranted the prediction that the skull would turn out
to be that of the opossum. It might just as well have been like that of
some other marsupial; or even like that of the totally different
group of Monotremes, of which the only living representatives are the
_Echidna_ and the _Ornithorhynchus._

For all practical purposes, however, the empirical laws of co-ordination
of structures, which are embodied in the generalisations of morphology,
may be confidently trusted, if employed with due caution, to lead to a
just interpretation of fossil remains; or, in other words, we may look
for the verification of the retrospective prophecies which are based
upon them.

And if this be the case, the late advances which have been made in
palaeontological discovery open out a new field for such prophecies. For
it has been ascertained with respect to many groups of animals, that, as
we trace them back in time, their ancestors gradually cease to exhibit
those special modifications which at present characterise the type, and
more nearly embody the general plan of the group to which they belong.

Thus, in the well-known case of the horse, the toes which are suppressed
in the living horse are found to be more and more complete in the older
members of the group, until, at the bottom of the Tertiary series of
America, we find an equine animal which has four toes in front and three
behind. No remains of the horse tribe are at present known from any
Mesozoic deposit. Yet who can doubt that, whenever a sufficiently
extensive series of lacustrine and fluviatile beds of that age becomes
known, the lineage which has been traced thus far will be continued by
equine quadrupeds with an increasing number of digits, until the horse
type merges in the five-toed form towards which these gradations point?

But the argument which holds good for the horse, holds good, not only
for all mammals, but for the whole animal world. And as the study of the
pedigrees, or lines of evolution, to which, at present, we have access,
brings to light, as it assuredly will do, the laws of that process, we
shall be able to reason from the facts with which the geological record
furnishes us to those which have hitherto remained, and many of which,
perhaps, may for ever remain, hidden. The same method of reasoning which
enables us, when furnished with a fragment of an extinct animal, to
prophesy the character which the whole organism exhibited, will,
sooner or later, enable us, when we know a few of the later terms of a
genealogical series, to predict the nature of the earlier terms.

In no very distant future, the method of Zadig, applied to a greater
body of facts than the present generation is fortunate enough to handle,
will enable the biologist to reconstruct the scheme of life from its
beginning, and to speak as confidently of the character of long extinct
beings, no trace of which has been preserved, as Zadig did of the
queen's spaniel and the king's horse. Let us hope that they may
be better rewarded for their toil and their sagacity than was the
Babylonian philosopher; for perhaps, by that time, the magi also may
be reckoned among the members of a forgotten Fauna, extinguished in the
struggle for existence against their great rival, common sense.




FOOTNOTES:

[Footnote 1: "Discours sur les revolutions de la surface du globe."
_Recherches sur les Ossemens Fossiles,_ Ed. iv, t.i. p.185.]

[Footnote 2: "On the Eclipses of Agathocles, Thales, and Xerxes,"
_Philosophical Transactions,_ vol. cxliii.]





End of Project Gutenberg's On the Method of Zadig, by Thomas Henry Huxley