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  SCIENCE AND CULTURE

  AND

  OTHER ESSAYS

[Illustration]

  SCIENCE AND CULTURE

  AND

  OTHER ESSAYS

  BY

  THOMAS HENRY HUXLEY, LL.D., F.R.S.


  London
  MACMILLAN AND CO.
  AND NEW YORK
  1888

  _All rights reserved_


  _First Edition printed 1881
  Reprinted 1882, 1888._




PREFACE.


The Addresses, Lectures, and Essays gathered together in this volume
have appeared at intervals during the past seven years, and I can give
no better reason for republishing them in their present form, than
the fact that three earlier collections of a similar nature have been
received with favour, and, indeed, have not yet ceased to be in request.

I beg leave to offer my best thanks to the Editors and Publishers of
the various publications in which these pieces have appeared, for their
kindly accorded permission to reprint them.

  LONDON. _October 1881._




CONTENTS.


  I.

  SCIENCE AND CULTURE.

  An Address delivered at the Opening of Sir Josiah Mason’s
  Science College, at Birmingham, on the 1st of October
  1880                                                   Pages 1 to 23


  II.

  UNIVERSITIES: ACTUAL AND IDEAL.

  The Inaugural Address of the Lord Rector of the
  University of Aberdeen, 27th February 1874.—_Contemporary
  Review_, 1874                                               24 to 64


  III.

  TECHNICAL EDUCATION.

  An Address delivered to the Working Men’s Club and
  Institute, 1st December 1877.—_Nineteenth Century_, 1878    65 to 85


  IV.

  ELEMENTARY INSTRUCTION IN PHYSIOLOGY.

  Read at the Meeting of the Domestic Economy Congress at
  Birmingham, 1877                                            86 to 93


  V.

  JOSEPH PRIESTLEY.

  An Address delivered on the occasion of the Presentation
  of a Statue of Priestley to the Town of Birmingham, on
  the 1st of August 1874.—_Macmillan’s Magazine_, 1874       94 to 127


  VI.

  ON THE METHOD OF ZADIG.

  A Lecture delivered at the Working Men’s College, Great
  Ormond Street, 1880.—_Nineteenth Century_, 1880           128 to 148


  VII.

  ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE
  VEGETABLE KINGDOMS.

  An Evening Lecture at the Royal Institution, Friday,
  January 28, 1876.—_Macmillan’s Magazine_, 1874            149 to 179


  VIII.

  ON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART
  ATTRIBUTED TO ARISTOTLE.

  _Nature_, 6th November 1879                               180 to 198


  IX.

  ON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS
  HISTORY.

  An Address delivered at the Meeting of the British
  Association for the Advancement of Science, at Belfast,
  1874.—_Fortnightly Review_, 1874                          199 to 245


  X.

  ON SENSATION AND THE UNITY OF STRUCTURE OF THE
  SENSIFEROUS ORGANS.

  An Evening Lecture at the Royal Institution, Friday,
  March 7, 1879.—_Nineteenth Century_, 1879                 246 to 273


  XI.

  EVOLUTION IN BIOLOGY.

  The _Encyclopædia Britannica_, Ninth Edition, vol. viii.
  1878                                                      274 to 309


  XII.

  THE COMING OF AGE OF “THE ORIGIN OF SPECIES.”

  An evening Lecture at the Royal Institution, Friday, 9th
  April 1880.—_Nature_, 1880                                310 to 324


  XIII.

  THE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE.

  An Address delivered at the Meeting of the International
  Medical Congress in London, 9th August 1881               325 to 349




I.

SCIENCE AND CULTURE.


Six years ago, as some of my present hearers may remember, I had the
privilege of addressing a large assemblage of the inhabitants of this
city, who had gathered together to do honour to the memory of their
famous townsman, Joseph Priestley;[1] and, if any satisfaction attaches
to posthumous glory, we may hope that the manes of the burnt-out
philosopher were then finally appeased.

No man, however, who is endowed with a fair share of common sense, and
not more than a fair share of vanity, will identify either contemporary
or posthumous fame with the highest good; and Priestley’s life leaves
no doubt that he, at any rate, set a much higher value upon the
advancement of knowledge, and the promotion of that freedom of thought
which is at once the cause and the consequence of intellectual progress.

Hence I am disposed to think that, if Priestley could be amongst us
to-day, the occasion of our meeting would afford him even greater
pleasure than the proceedings which celebrated the centenary of his
chief discovery. The kindly heart would be moved, the high sense
of social duty would be satisfied, by the spectacle of well-earned
wealth, neither squandered in tawdry luxury and vainglorious show,
nor scattered with the careless charity which blesses neither him
that gives nor him that takes, but expended in the execution of a
well-considered plan for the aid of present and future generations of
those who are willing to help themselves.

We shall all be of one mind thus far. But it is needful to share
Priestley’s keen interest in physical science; and to have learned, as
he had learned, the value of scientific training in fields of inquiry
apparently far remote from physical science; in order to appreciate, as
he would have appreciated, the value of the noble gift which Sir Josiah
Mason has bestowed upon the inhabitants of the Midland district.

For us children of the nineteenth century, however, the establishment
of a college under the conditions of Sir Josiah Mason’s Trust, has a
significance apart from any which it could have possessed a hundred
years ago. It appears to be an indication that we are reaching the
crisis of the battle, or rather of the long series of battles, which
have been fought over education in a campaign which began long before
Priestley’s time, and will probably not be finished just yet.

In the last century, the combatants were the champions of ancient
literature, on the one side, and those of modern literature on the
other; but, some thirty years[2] ago, the contest became complicated by
the appearance of a third army, ranged round the banner of Physical
Science.

I am not aware that any one has authority to speak in the name of this
new host. For it must be admitted to be somewhat of a guerilla force,
composed largely of irregulars, each of whom fights pretty much for
his own hand. But the impressions of a full private, who has seen a
good deal of service in the ranks, respecting the present position of
affairs and the conditions of a permanent peace, may not be devoid
of interest; and I do not know that I could make a better use of the
present opportunity than by laying them before you.


From the time that the first suggestion to introduce physical science
into ordinary education was timidly whispered, until now, the advocates
of scientific education have met with opposition of two kinds. On the
one hand, they have been pooh-poohed by the men of business who pride
themselves on being the representatives of practicality; while, on the
other hand, they have been excommunicated by the classical scholars,
in their capacity of Levites in charge of the ark of culture and
monopolists of liberal education.

The practical men believed that the idol whom they worship—rule of
thumb—has been the source of the past prosperity, and will suffice
for the future welfare of the arts and manufactures. They were of
opinion that science is speculative rubbish; that theory and practice
have nothing to do with one another; and that the scientific habit of
mind is an impediment, rather than an aid, in the conduct of ordinary
affairs.

I have used the past tense in speaking of the practical men—for
although they were very formidable thirty years ago, I am not sure
that the pure species has not been extirpated. In fact, so far as mere
argument goes, they have been subjected to such a _feu d’enfer_ that it
is a miracle if any have escaped. But I have remarked that your typical
practical man has an unexpected resemblance to one of Milton’s angels.
His spiritual wounds, such as are inflicted by logical weapons, may be
as deep as a well and as wide as a church door, but beyond shedding a
few drops of ichor, celestial or otherwise, he is no whit the worse.
So, if any of these opponents be left, I will not waste time in vain
repetition of the demonstrative evidence of the practical value of
science; but knowing that a parable will sometimes penetrate where
syllogisms fail to effect an entrance, I will offer a story for their
consideration.

Once upon a time, a boy, with nothing to depend upon but his own
vigorous nature, was thrown into the thick of the struggle for
existence in the midst of a great manufacturing population. He seems
to have had a hard fight, inasmuch as, by the time he was thirty
years of age, his total disposable funds amounted to twenty pounds.
Nevertheless, middle life found him giving proof of his comprehension
of the practical problems he had been roughly called upon to solve, by
a career of remarkable prosperity.

Finally, having reached old age with its well-earned surroundings of
“honour, troops of friends,” the hero of my story bethought himself of
those who were making a like start in life, and how he could stretch
out a helping hand to them.

After long and anxious reflection this successful practical man
of business could devise nothing better than to provide them with
the means of obtaining “sound, extensive, and practical scientific
knowledge.” And he devoted a large part of his wealth and five years of
incessant work to this end.

I need not point the moral of a tale which, as the solid and spacious
fabric of the Scientific College assures us, is no fable, nor can
anything which I could say intensify the force of this practical answer
to practical objections.


We may take it for granted then, that, in the opinion of those best
qualified to judge, the diffusion of thorough scientific education is
an absolutely essential condition of industrial progress; and that the
College which has been opened to-day will confer an inestimable boon
upon those whose livelihood is to be gained by the practice of the arts
and manufactures of the district.

The only question worth discussion is, whether the conditions, under
which the work of the College is to be carried out, are such as to give
it the best possible chance of achieving permanent success.

Sir Josiah Mason, without doubt most wisely, has left very large
freedom of action to the trustees, to whom he proposes ultimately to
commit the administration of the College, so that they may be able to
adjust its arrangements in accordance with the changing conditions
of the future. But, with respect to three points, he has laid most
explicit injunctions upon both administrators and teachers.

Party politics are forbidden to enter into the minds of either, so
far as the work of the College is concerned; theology is as sternly
banished from its precincts; and finally, it is especially declared
that the College shall make no provision for “mere literary instruction
and education.”

It does not concern me at present to dwell upon the first two
injunctions any longer than may be needful to express my full
conviction of their wisdom. But the third prohibition brings us face to
face with those other opponents of scientific education, who are by no
means in the moribund condition of the practical man, but alive, alert,
and formidable.

It is not impossible that we shall hear this express exclusion
of “literary instruction and education” from a College which,
nevertheless, professes to give a high and efficient education, sharply
criticised. Certainly the time was that the Levites of culture would
have sounded their trumpets against its walls as against an educational
Jericho.

How often have we not been told that the study of physical science
is incompetent to confer culture; that it touches none of the higher
problems of life; and, what is worse, that the continual devotion to
scientific studies tends to generate a narrow and bigoted belief in
the applicability of scientific methods to the search after truth of
all kinds. How frequently one has reason to observe that no reply to
a troublesome argument tells so well as calling its author a “mere
scientific specialist.” And, as I am afraid it is not permissible to
speak of this form of opposition to scientific education in the past
tense; may we not expect to be told that this, not only omission, but
prohibition, of “mere literary instruction and education” is a patent
example of scientific narrow-mindedness?

I am not acquainted with Sir Josiah Mason’s reasons for the action
which he has taken; but if, as I apprehend is the case, he refers to
the ordinary classical course of our schools and universities by the
name of “mere literary instruction and education,” I venture to offer
sundry reasons of my own in support of that action.

For I hold very strongly by two convictions—The first is, that neither
the discipline nor the subject-matter of classical education is of
such direct value to the student of physical science as to justify
the expenditure of valuable time upon either; and the second is, that
for the purpose of attaining real culture, an exclusively scientific
education is at least as effectual as an exclusively literary education.

I need hardly point out to you that these opinions, especially the
latter, are diametrically opposed to those of the great majority of
educated Englishmen, influenced as they are by school and university
traditions. In their belief, culture is obtainable only by a liberal
education; and a liberal education is synonymous, not merely with
education and instruction in literature, but in one particular form of
literature, namely, that of Greek and Roman antiquity. They hold that
the man who has learned Latin and Greek, however little, is educated;
while he who is versed in other branches of knowledge, however deeply,
is a more or less respectable specialist, not admissible into the
cultured caste. The stamp of the educated man, the University degree,
is not for him.

I am too well acquainted with the generous catholicity of spirit, the
true sympathy with scientific thought, which pervades the writings
of our chief apostle of culture to identify him with these opinions;
and yet one may cull from one and another of those epistles to the
Philistines, which so much delight all who do not answer to that name,
sentences which lend them some support.

Mr. Arnold tells us that the meaning of culture is “to know the best
that has been thought and said in the world.” It is the criticism of
life contained in literature. That criticism regards “Europe as being,
for intellectual and spiritual purposes, one great confederation, bound
to a joint action and working to a common result; and whose members
have, for their common outfit, a knowledge of Greek, Roman, and Eastern
antiquity, and of one another. Special, local, and temporary advantages
being put out of account, that modern nation will in the intellectual
and spiritual sphere make most progress, which most thoroughly carries
out this programme. And what is that but saying that we too, all of us,
as individuals, the more thoroughly we carry it out, shall make the
more progress?”[3]

We have here to deal with two distinct propositions. The first, that
a criticism of life is the essence of culture; the second, that
literature contains the materials which suffice for the construction of
such a criticism.

I think that we must all assent to the first proposition. For
culture certainly means something quite different from learning or
technical skill. It implies the possession of an ideal, and the habit
of critically estimating the value of things by comparison with a
theoretic standard. Perfect culture should supply a complete theory of
life, based upon a clear knowledge alike of its possibilities and of
its limitations.

But we may agree to all this, and yet strongly dissent from the
assumption that literature alone is competent to supply this knowledge.
After having learnt all that Greek, Roman, and Eastern antiquity have
thought and said, and all that modern literatures have to tell us, it
is not self-evident that we have laid a sufficiently broad and deep
foundation for that criticism of life which constitutes culture.

Indeed, to any one acquainted with the scope of physical science, it is
not at all evident. Considering progress only in the “intellectual and
spiritual sphere,” I find myself wholly unable to admit that either
nations or individuals will really advance, if their common outfit
draws nothing from the stores of physical science. I should say that
an army, without weapons of precision and with no particular base of
operations, might more hopefully enter upon a campaign on the Rhine,
than a man, devoid of a knowledge of what physical science has done in
the last century, upon a criticism of life.


When a biologist meets with an anomaly, he instinctively turns to the
study of development to clear it up. The rationale of contradictory
opinions may with equal confidence be sought in history.

It is, happily, no new thing that Englishmen should employ their wealth
in building and endowing institutions for educational purposes. But,
five or six hundred years ago, deeds of foundation expressed or implied
conditions as nearly as possible contrary to those which have been
thought expedient by Sir Josiah Mason. That is to say, physical science
was practically ignored, while a certain literary training was enjoined
as a means to the acquirement of knowledge which was essentially
theological.

The reason of this singular contradiction between the actions of men
alike animated by a strong and disinterested desire to promote the
welfare of their fellows, is easily discovered.

At that time, in fact, if any one desired knowledge beyond such as
could be obtained by his own observation, or by common conversation,
his first necessity was to learn the Latin language, inasmuch as
all the higher knowledge of the western world was contained in works
written in that language. Hence, Latin grammar, with logic and
rhetoric, studied through Latin, were the fundamentals of education.
With respect to the substance of the knowledge imparted through this
channel, the Jewish and Christian Scriptures, as interpreted and
supplemented by the Romish Church, were held to contain a complete and
infallibly true body of information.

Theological dicta were, to the thinkers of those days, that which
the axioms and definitions of Euclid are to the geometers of these.
The business of the philosophers of the middle ages was to deduce
from the data furnished by the theologians, conclusions in accordance
with ecclesiastical decrees. They were allowed the high privilege of
showing, by logical process, how and why that which the Church said
was true, must be true. And if their demonstrations fell short of or
exceeded this limit, the Church was maternally ready to check their
aberrations, if need be, by the help of the secular arm.

Between the two, our ancestors were furnished with a compact and
complete criticism of life. They were told how the world began and
how it would end; they learned that all material existence was but a
base and insignificant blot upon the fair face of the spiritual world,
and that nature was, to all intents and purposes, the playground of
the devil; they learned that the earth is the centre of the visible
universe, and that man is the cynosure of things terrestrial; and more
especially was it inculcated that the course of nature had no fixed
order, but that it could be, and constantly was, altered by the agency
of innumerable spiritual beings, good and bad, according as they were
moved by the deeds and prayers of men. The sum and substance of the
whole doctrine was to produce the conviction that the only thing really
worth knowing in this world was how to secure that place in a better
which, under certain conditions, the Church promised.

Our ancestors had a living belief in this theory of life, and acted
upon it in their dealings with education, as in all other matters.
Culture meant saintliness—after the fashion of the saints of those
days; the education that led to it was, of necessity, theological; and
the way to theology lay through Latin.

That the study of nature—further than was requisite for the
satisfaction of everyday wants—should have any bearing on human life
was far from the thoughts of men thus trained. Indeed, as nature had
been cursed for man’s sake, it was an obvious conclusion that those who
meddled with nature were likely to come into pretty close contact with
Satan. And, if any born scientific investigator followed his instincts,
he might safely reckon upon earning the reputation, and probably upon
suffering the fate, of a sorcerer.

Had the western world been left to itself in Chinese isolation, there
is no saying how long this state of things might have endured. But,
happily, it was not left to itself. Even earlier than the thirteenth
century, the development of Moorish civilisation in Spain and the
great movement of the Crusades had introduced the leaven which, from
that day to this, has never ceased to work. At first, through the
intermediation of Arabic translations, afterwards, by the study of the
originals, the western nations of Europe became acquainted with the
writings of the ancient philosophers and poets, and, in time, with the
whole of the vast literature of antiquity.

Whatever there was of high intellectual aspiration or dominant
capacity in Italy, France, Germany, and England, spent itself for
centuries in taking possession of the rich inheritance left by the dead
civilisations of Greece and Rome. Marvellously aided by the invention
of printing, classical learning spread and flourished. Those who
possessed it prided themselves on having attained the highest culture
then within the reach of mankind.

And justly. For, saving Dante on his solitary pinnacle, there was no
figure in modern literature at the time of the Renascence to compare
with the men of antiquity; there was no art to compete with their
sculpture; there was no physical science but that which Greece had
created. Above all, there was no other example of perfect intellectual
freedom—of the unhesitating acceptance of reason as the sole guide to
truth and the supreme arbiter of conduct.

The new learning necessarily soon exerted a profound influence upon
education. The language of the monks and schoolmen seemed little better
than gibberish to scholars fresh from Virgil and Cicero, and the study
of Latin was placed upon a new foundation. Moreover, Latin itself
ceased to afford the sole key to knowledge. The student who sought the
highest thought of antiquity, found only a second-hand reflection of
it in Roman literature, and turned his face to the full light of the
Greeks. And after a battle, not altogether dissimilar to that which
is at present being fought over the teaching of physical science, the
study of Greek was recognised as an essential element of all higher
education.

Thus the Humanists, as they were called, won the day; and the great
reform which they effected was of incalculable service to mankind.
But the Nemesis of all reformers is finality; and the reformers of
education, like those of religion, fell into the profound, however
common, error of mistaking the beginning for the end of the work of
reformation.

The representatives of the Humanists, in the nineteenth century, take
their stand upon classical education as the sole avenue to culture, as
firmly as if we were still in the age of Renascence. Yet, surely, the
present intellectual relations of the modern and the ancient worlds are
profoundly different from those which obtained three centuries ago.
Leaving aside the existence of a great and characteristically modern
literature, of modern painting, and, especially, of modern music,
there is one feature of the present state of the civilised world which
separates it more widely from the Renascence, than the Renascence was
separated from the middle ages.

This distinctive character of our own times lies in the vast and
constantly increasing part which is played by natural knowledge. Not
only is our daily life shaped by it, not only does the prosperity
of millions of men depend upon it, but our whole theory of life has
long been influenced, consciously or unconsciously, by the general
conceptions of the universe, which have been forced upon us by physical
science.

In fact, the most elementary acquaintance with the results of
scientific investigation shows us that they offer a broad and striking
contradiction to the opinions so implicitly credited and taught in the
middle ages.

The notions of the beginning and the end of the world entertained
by our forefathers are no longer credible. It is very certain that
the earth is not the chief body in the material universe, and that
the world is not subordinated to man’s use. It is even more certain
that nature is the expression of a definite order with which nothing
interferes, and that the chief business of mankind is to learn that
order and govern themselves accordingly. Moreover this scientific
“criticism of life” presents itself to us with different credentials
from any other. It appeals not to authority, nor to what anybody
may have thought or said, but to nature. It admits that all our
interpretations of natural fact are more or less imperfect and
symbolic, and bids the learner seek for truth not among words but among
things. It warns us that the assertion which outstrips evidence is not
only a blunder but a crime.

The purely classical education advocated by the representatives of
the Humanists in our day, gives no inkling of all this. A man may be
a better scholar than Erasmus, and know no more of the chief causes
of the present intellectual fermentation than Erasmus did. Scholarly
and pious persons, worthy of all respect, favour us with allocutions
upon the sadness of the antagonism of science to their mediæval way
of thinking, which betray an ignorance of the first principles of
scientific investigation, an incapacity for understanding what a man
of science means by veracity, and an unconsciousness of the weight of
established scientific truths, which is almost comical.

There is no great force in the _tu quoque_ argument, or else the
advocates of scientific education might fairly enough retort upon the
modern Humanists that they may be learned specialists, but that they
possess no such sound foundation for a criticism of life as deserves
the name of culture. And, indeed, if we were disposed to be cruel,
we might urge that the Humanists have brought this reproach upon
themselves, not because they are too full of the spirit of the ancient
Greek, but because they lack it.

The period of the Renascence is commonly called that of the “Revival of
Letters,” as if the influences then brought to bear upon the mind of
Western Europe had been wholly exhausted in the field of literature.
I think it is very commonly forgotten that the revival of science,
effected by the same agency, although less conspicuous, was not less
momentous.

In fact, the few and scattered students of nature of that day picked
up the clue to her secrets exactly as it fell from the hands of the
Greeks a thousand years before. The foundations of mathematics were so
well laid by them, that our children learn their geometry from a book
written for the schools of Alexandria two thousand years ago. Modern
astronomy is the natural continuation and development of the work of
Hipparchus and of Ptolemy; modern physics of that of Democritus and of
Archimedes; it was long before modern biological science outgrew the
knowledge bequeathed to us by Aristotle, by Theophrastus, and by Galen.

We cannot know all the best thoughts and sayings of the Greeks unless
we know what they thought about natural phenomena. We cannot fully
apprehend their criticism of life unless we understand the extent
to which that criticism was affected by scientific conceptions. We
falsely pretend to be the inheritors of their culture, unless we are
penetrated, as the best minds among them were, with an unhesitating
faith that the free employment of reason, in accordance with scientific
method, is the sole method of reaching truth.

Thus I venture to think that the pretensions of our modern Humanists
to the possession of the monopoly of culture and to the exclusive
inheritance of the spirit of antiquity must be abated, if not
abandoned. But I should be very sorry that anything I have said should
be taken to imply a desire on my part to depreciate the value of
classical education, as it might be and as it sometimes is. The native
capacities of mankind vary no less than their opportunities; and while
culture is one, the road by which one man may best reach it is widely
different from that which is most advantageous to another. Again,
while scientific education is yet inchoate and tentative, classical
education is thoroughly well organised upon the practical experience
of generations of teachers. So that, given ample time for learning and
destination for ordinary life, or for a literary career, I do not think
that a young Englishman in search of culture can do better than follow
the course usually marked out for him, supplementing its deficiencies
by his own efforts.

But for those who mean to make science their serious occupation; or who
intend to follow the profession of medicine; or who have to enter early
upon the business of life; for all these, in my opinion, classical
education is a mistake; and it is for this reason that I am glad to see
“mere literary education and instruction” shut out from the curriculum
of Sir Josiah Mason’s College, seeing that its inclusion would probably
lead to the introduction of the ordinary smattering of Latin and Greek.

Nevertheless, I am the last person to question the importance of
genuine literary education, or to suppose that intellectual culture can
be complete without it. An exclusively scientific training will bring
about a mental twist as surely as an exclusively literary training. The
value of the cargo does not compensate for a ship’s being out of trim;
and I should be very sorry to think that the Scientific College would
turn out none but lop-sided men.

There is no need, however, that such a catastrophe should happen.
Instruction in English, French, and German is provided, and thus the
three greatest literatures of the modern world are made accessible to
the student.

French and German, and especially the latter language, are absolutely
indispensable to those who desire full knowledge in any department
of science. But even supposing that the knowledge of these languages
acquired is not more than sufficient for purely scientific purposes,
every Englishman has, in his native tongue, an almost perfect
instrument of literary expression; and, in his own literature, models
of every kind of literary excellence. If an Englishman cannot get
literary culture out of his Bible, his Shakspeare, his Milton, neither,
in my belief, will the profoundest study of Homer and Sophocles, Virgil
and Horace, give it to him.

Thus, since the constitution of the College makes sufficient provision
for literary as well as for scientific education, and since artistic
instruction is also contemplated, it seems to me that a fairly complete
culture is offered to all who are willing to take advantage of it.


But I am not sure that at this point the “practical” man, scotched but
not slain, may ask what all this talk about culture has to do with
an Institution, the object of which is defined to be “to promote the
prosperity of the manufactures and the industry of the country.” He
may suggest that what is wanted for this end is not culture, nor even
a purely scientific discipline, but simply a knowledge of applied
science.

I often wish that this phrase, “applied science,” had never been
invented. For it suggests that there is a sort of scientific knowledge
of direct practical use, which can be studied apart from another sort
of scientific knowledge, which is of no practical utility, and which
is termed “pure science.” But there is no more complete fallacy than
this. What people call applied science is nothing but the application
of pure science to particular classes of problems. It consists of
deductions from those general principles, established by reasoning and
observation, which constitute pure science. No one can safely make
these deductions until he has a firm grasp of the principles; and he
can obtain that grasp only by personal experience of the operations of
observation and of reasoning on which they are founded.

Almost all the processes employed in the arts and manufactures fall
within the range either of physics or of chemistry. In order to improve
them, one must thoroughly understand them; and no one has a chance
of really understanding them, unless he has obtained that mastery
of principles and that habit of dealing with facts, which is given
by long-continued and well-directed purely scientific training in
the physical and the chemical laboratory. So that there really is no
question as to the necessity of purely scientific discipline, even if
the work of the College were limited by the narrowest interpretation of
its stated aims.

And, as to the desirableness of a wider culture than that yielded
by science alone, it is to be recollected that the improvement of
manufacturing processes is only one of the conditions which contribute
to the prosperity of industry. Industry is a means and not an end; and
mankind work only to get something which they want. What that something
is depends partly on their innate, and partly on their acquired,
desires.

If the wealth resulting from prosperous industry is to be spent upon
the gratification of unworthy desires, if the increasing perfection
of manufacturing processes is to be accompanied by an increasing
debasement of those who carry them on, I do not see the good of
industry and prosperity.

Now it is perfectly true that men’s views of what is desirable depend
upon their characters; and that the innate proclivities to which we
give that name are not touched by any amount of instruction. But it
does not follow that even mere intellectual education may not, to an
indefinite extent, modify the practical manifestation of the characters
of men in their actions, by supplying them with motives unknown to the
ignorant. A pleasure-loving character will have pleasure of some sort;
but, if you give him the choice, he may prefer pleasures which do not
degrade him to those which do. And this choice is offered to every man,
who possesses in literary or artistic culture a never-failing source of
pleasures, which are neither withered by age, nor staled by custom, nor
embittered in the recollection by the pangs of self-reproach.

If the Institution opened to-day fulfils the intention of its founder,
the picked intelligences among all classes of the population of
this district will pass through it. No child born in Birmingham,
henceforward, if he have the capacity to profit by the opportunities
offered to him, first in the primary and other schools, and afterwards
in the Scientific College, need fail to obtain, not merely the
instruction, but the culture most appropriate to the conditions of his
life.

Within these walls, the future employer and the future artisan may
sojourn together for a while, and carry, through all their lives, the
stamp of the influences then brought to bear upon them. Hence, it is
not beside the mark to remind you, that the prosperity of industry
depends not merely upon the improvement of manufacturing processes,
not merely upon the ennobling of the individual character, but upon a
third condition, namely, a clear understanding of the conditions of
social life on the part of both the capitalist and the operative, and
their agreement upon common principles of social action. They must
learn that social phenomena are as much the expression of natural laws
as any others; that no social arrangements can be permanent unless
they harmonise with the requirements of social statics and dynamics;
and that, in the nature of things, there is an arbiter whose decisions
execute themselves.

But this knowledge is only to be obtained by the application of
the methods of investigation adopted in physical researches to the
investigation of the phenomena of society. Hence, I confess, I should
like to see one addition made to the excellent scheme of education
propounded for the College, in the shape of provision for the teaching
of Sociology. For though we are all agreed that party politics are to
have no place in the instruction of the College; yet in this country,
practically governed as it is now by universal suffrage, every man who
does his duty must exercise political functions. And, if the evils
which are inseparable from the good of political liberty are to be
checked, if the perpetual oscillation of nations between anarchy and
despotism is to be replaced by the steady march of self-restraining
freedom; it will be because men will gradually bring themselves to deal
with political, as they now deal with scientific questions; to be as
ashamed of undue haste and partisan prejudice in the one case as in
the other; and to believe that the machinery of society is at least
as delicate as that of a spinning-jenny, and as little likely to be
improved by the meddling of those who have not taken the trouble to
master the principles of its action.


In conclusion, I am sure that I make myself the mouthpiece of all
present in offering to the venerable founder of the Institution,
which now commences its beneficent career, our congratulations on the
completion of his work; and in expressing the conviction, that the
remotest posterity will point to it as a crucial instance of the wisdom
which natural piety leads all men to ascribe to their ancestors.




II.

UNIVERSITIES: ACTUAL AND IDEAL.


Elected by the suffrages of your four Nations, Rector of the ancient
University of which you are scholars, I take the earliest opportunity
which has presented itself since my restoration to health, of
delivering the Address which, by long custom, is expected of the holder
of my office.

My first duty in opening that Address, is to offer you my most hearty
thanks for the signal honour you have conferred upon me—an honour
of which, as a man unconnected with you by personal or by national
ties, devoid of political distinction, and a plebeian who stands by
his order, I could not have dreamed. And it was the more surprising
to me, as the five-and-twenty years which have passed over my head
since I reached intellectual manhood, have been largely spent in no
half-hearted advocacy of doctrines which have not yet found favour
in the eyes of Academic respectability; so that, when the proposal
to nominate me for your Rector came, I was almost as much astonished
as was Hal o’ the Wynd, “who fought for his own hand,” by the Black
Douglas’s proffer of knighthood. And I fear that my acceptance must be
taken as evidence that, less wise than the Armourer of Perth, I have
not yet done with soldiering.

In fact, if, for a moment, I imagined that your intention was simply,
in the kindness of your hearts, to do me honour; and that the Rector of
your University, like that of some other Universities, was one of those
happy beings who sit in glory for three years, with nothing to do for
it save the making of a speech, a conversation with my distinguished
predecessor soon dispelled the dream. I found that, by the constitution
of the University of Aberdeen, the incumbent of the Rectorate is, if
not a power, at any rate a potential energy; and that, whatever may
be his chances of success or failure, it is his duty to convert that
potential energy into a living force, directed towards such ends as may
seem to him conducive to the welfare of the corporation of which he is
the theoretical head.

I need not tell you that your late Lord Rector took this view of
his position, and acted upon it with the comprehensive, far-seeing
insight into the actual condition and tendencies, not merely of his
own, but of other countries, which is his honourable characteristic
among statesmen. I have already done my best, and, as long as I hold
my office, I shall continue my endeavours, to follow in the path which
he trod; to do what in me lies, to bring this University nearer to the
ideal—alas, that I should be obliged to say ideal—of all Universities;
which, as I conceive, should be places in which thought is free from
all fetters; and in which all sources of knowledge, and all aids to
learning, should be accessible to all comers, without distinction of
creed or country, riches or poverty.

Do not suppose, however, that I am sanguine enough to expect much to
come of any poor efforts of mine. If your annals take any notice of my
incumbency, I shall probably go down to posterity as the Rector who was
always beaten. But if they add, as I think they will, that my defeats
became victories in the hands of my successors, I shall be well content.


The scenes are shifting in the great theatre of the world. The act
which commenced with the Protestant Reformation is nearly played
out, and a wider and a deeper change than that effected three
centuries ago—a reformation, or rather a revolution of thought, the
extremes of which are represented by the intellectual heirs of John
of Leyden and of Ignatius Loyola, rather than by those of Luther
and of Leo—is waiting to come on, nay, visible behind the scenes to
those who have good eyes. Men are beginning, once more, to awake to
the fact that matters of belief and of speculation are of absolutely
infinite practical importance; and are drawing off from that sunny
country “where it is always afternoon”—the sleepy hollow of broad
indifferentism—to range themselves under their natural banners.
Change is in the air. It is whirling feather-heads into all sorts of
eccentric orbits, and filling the steadiest with a sense of insecurity.
It insists on reopening all questions and asking all institutions,
however venerable, by what right they exist, and whether they are, or
are not, in harmony with the real or supposed wants of mankind. And
it is remarkable that these searching inquiries are not so much forced
on institutions from without, as developed from within. Consummate
scholars question the value of learning; priests condemn dogma; and
women turn their backs upon man’s ideal of perfect womanhood, and seek
satisfaction in apocalyptic visions of some, as yet unrealised, epicene
reality.

If there be a type of stability in this world, one would be inclined
to look for it in the old Universities of England. But it has been my
business of late to hear a good deal about what is going on in these
famous corporations; and I have been filled with astonishment by the
evidences of internal fermentation which they exhibit. If Gibbon
could revisit the ancient seat of learning of which he has written so
cavalierly, assuredly he would no longer speak of “the monks of Oxford
sunk in prejudice and port.” There, as elsewhere, port has gone out
of fashion, and so has prejudice—at least that particular fine, old,
crusted sort of prejudice to which the great historian alludes.

Indeed, things are moving so fast in Oxford and Cambridge, that, for my
part, I rejoiced when the Royal Commission, of which I am a member, had
finished and presented the Report which related to these Universities;
for we should have looked like mere plagiarists, if, in consequence
of a little longer delay in issuing it, all the measures of reform
we proposed had been anticipated by the spontaneous action of the
Universities themselves.

A month ago I should have gone on to say that one might speedily
expect changes of another kind in Oxford and Cambridge. A Commission
has been inquiring into the revenues of the many wealthy societies, in
more or less direct connection with the Universities, resident in those
towns. It is said that the Commission has reported, and that, for the
first time in recorded history, the nation, and perhaps the Colleges
themselves, will know what they are worth. And it was announced that a
statesman, who, whatever his other merits or defects, has aims above
the level of mere party fighting, and a clear vision into the most
complex practical problems, meant to deal with these revenues.

But, _Bos locutus est._ That mysterious independent variable of
political calculation, Public Opinion—which some whisper is, in the
present case, very much the same thing as publican’s opinion—has willed
otherwise. The Heads may return to their wonted slumbers—at any rate
for a space.

Is the spirit of change, which is working thus vigorously in the South,
likely to affect the Northern Universities, and if so, to what extent?
The violence of fermentation depends, not so much on the quantity of
the yeast, as on the composition of the wort, and its richness in
fermentable material; and, as a preliminary to the discussion of this
question, I venture to call to your minds the essential and fundamental
differences between the Scottish and the English type of University.

Do not charge me with anything worse than official egotism, if I say
that these differences appear to be largely symbolised by my own
existence. There is no Rector in an English University. Now, the
organisation of the members of an University into Nations, with their
elective Rector, is the last relic of the primitive constitution of
Universities. The Rectorate was the most important of all offices in
that University of Paris, upon the model of which the University of
Aberdeen was fashioned; and which was certainly a great and flourishing
institution in the twelfth century.

Enthusiasts for the antiquity of one of the two acknowledged parents
of all Universities, indeed, do not hesitate to trace the origin of
the “Studium Parisiense” up to that wonderful king of the Franks and
Lombards, Karl, surnamed the Great, whom we all called Charlemagne, and
believed to be a Frenchman, until a learned historian, by beneficent
iteration, taught us better. Karl is said not to have been much of a
scholar himself, but he had the wisdom of which knowledge is only the
servitor. And that wisdom enabled him to see that ignorance is one of
the roots of all evil.

In the Capitulary which enjoins the foundation of monasterial and
cathedral schools, he says: “Right action is better than knowledge;
but in order to do what is right, we must know what is right.”[4] An
irrefragable truth, I fancy. Acting upon it, the king took pretty full
compulsory powers, and carried into effect a really considerable and
effectual scheme of elementary education through the length and breadth
of his dominions.

No doubt the idolaters out by the Elbe, in what is now part of Prussia,
objected to the Frankish king’s measures; no doubt the priests, who had
never hesitated about sacrificing all unbelievers in their fantastic
deities and futile conjurations, were the loudest in chanting the
virtues of toleration; no doubt they denounced as a cruel persecutor
the man who would not allow them, however sincere they might be, to go
on spreading delusions which debased the intellect, as much as they
deadened the moral sense, and undermined the bonds of civil allegiance;
no doubt, if they had lived in these times, they would have been able
to show, with ease, that the king’s proceedings were totally contrary
to the best liberal principles. But it may be said, in justification of
the Teutonic ruler, first, that he was born before those principles,
and did not suspect that the best way of getting disorder into order
was to let it alone; and, secondly, that his rough and questionable
proceedings did, more or less, bring about the end he had in view. For,
in a couple of centuries, the schools he sowed broadcast produced their
crop of men, thirsting for knowledge and craving for culture. Such men
gravitating towards Paris, as a light amidst the darkness of evil days,
from Germany, from Spain, from Britain, and from Scandinavia, came
together by natural affinity. By degrees they banded themselves into a
society, which, as its end was the knowledge of all things knowable,
called itself a “_Studium Generale_;” and when it had grown into a
recognised corporation, acquired the name of “_Universitas Studii
Generalis_,” which, mark you, means not a “Useful Knowledge Society,”
but a “Knowledge-of-things-in-general Society.”

And thus the first “University,” at any rate on this side of the Alps,
came into being. Originally it had but one Faculty, that of Arts. Its
aim was to be a centre of knowledge and culture; not to be, in any
sense, a technical school.

The scholars seem to have studied Grammar, Logic, and Rhetoric;
Arithmetic and Geometry; Astronomy; Theology; and Music. Thus, their
work, however imperfect and faulty, judged by modern lights, it may
have been, brought them face to face with all the leading aspects of
the many-sided mind of man. For these studies did really contain, at
any rate in embryo—sometimes, it may be, in caricature—what we now call
Philosophy, Mathematical and Physical Science, and Art. And I doubt if
the curriculum of any modern University shows so clear and generous
a comprehension of what is meant by culture, as this old Trivium and
Quadrivium does.

The students who had passed through the University course, and had
proved themselves competent to teach, became masters and teachers of
their younger brethren. Whence the distinction of Masters and Regents
on the one hand, and Scholars on the other.

Rapid growth necessitated organisation. The Masters and Scholars of
various tongues and countries grouped themselves into four Nations; and
the Nations, by their own votes at first, and subsequently by those
of their Procurators, or representatives, elected their supreme head
and governor, the Rector—at that time the sole representative of the
University, and a very real power, who could defy Provosts interfering
from without; or could inflict even corporal punishment on disobedient
members within the University.

Such was the primitive constitution of the University of Paris. It is
in reference to this original state of things that I have spoken of the
Rectorate, and all that appertains to it, as the sole relic of that
constitution.

But this original organisation did not last long. Society was not
then, any more than it is now, patient of culture, as such. It says to
everything, “Be useful to me, or away with you.” And to the learned,
the unlearned man said then, as he does now, “What is the use of all
your learning, unless you can tell me what I want to know? I am here
blindly groping about, and constantly damaging myself by collision
with three mighty powers, the power of the invisible God, the power
of my fellow Man, and the power of brute Nature. Let your learning
be turned to the study of these powers, that I may know how I am to
comport myself with regard to them.” In answer to this demand, some
of the Masters of the Faculty of Arts devoted themselves to the study
of Theology, some to that of Law, and some to that of Medicine; and
they became Doctors—men learned in those technical, or, as we now call
them, professional, branches of knowledge. Like cleaving to like, the
Doctors formed schools, or Faculties, of Theology, Law, and Medicine,
which sometimes assumed airs of superiority over their parent, the
Faculty of Arts, though the latter always asserted and maintained its
fundamental supremacy.

The Faculties arose by process of natural differentiation out of the
primitive University. Other constituents, foreign to its nature,
were speedily grafted upon it. One of these extraneous elements was
forced into it by the Roman Church, which in those days asserted with
effect, that which it now asserts, happily without any effect in these
realms, its right of censorship and control over all teaching. The
local habitation of the University lay partly in the lands attached to
the monastery of S. Geneviève, partly in the diocese of the Bishop of
Paris; and he who would teach must have the licence of the Abbot, or of
the Bishop, as the nearest representative of the Pope, so to do, which
licence was granted by the Chancellors of these Ecclesiastics.

Thus, if I am what archæologists call a “survival” of the primitive
head and ruler of the University, your Chancellor stands in the same
relation to the Papacy; and, with all respect for his Grace, I think
I may say that we both look terribly shrunken when compared with our
great originals.

Not so is it with a second foreign element, which silently dropped
into the soil of Universities, like the grain of mustard-seed in the
parable; and, like that grain, grew into a tree, in whose branches
a whole aviary of fowls took shelter. That element is the element
of Endowment. It differed from the preceding, in its original design
to serve as a prop to the young plant, not to be a parasite upon it.
The charitable and the humane, blessed with wealth, were very early
penetrated by the misery of the poor student. And the wise saw that
intellectual ability is not so common or so unimportant a gift that it
should be allowed to run to waste upon mere handicrafts and chares.
The man who was a blessing to his contemporaries, but who so often has
been converted into a curse, by the blind adherence of his posterity
to the letter, rather than to the spirit, of his wishes—I mean the
“pious founder”—gave money and lands, that the student, who was rich in
brain and poor in all else, might be taken from the plough or from the
stithy, and enabled to devote himself to the higher service of mankind;
and built colleges and halls in which he might be not only housed and
fed, but taught.

The Colleges were very generally placed in strict subordination to the
University by their founders; but, in many cases, their endowment,
consisting of land, has undergone an “unearned increment,” which has
given these societies a continually increasing weight and importance
as against the unendowed, or fixedly endowed, University. In Pharaoh’s
dream, the seven lean kine eat up the seven fat ones. In the reality of
historical fact, the fat Colleges have eaten up the lean Universities.

Even here in Aberdeen, though the causes at work may have been
somewhat different, the effects have been similar; and you see how
much more substantial an entity is the Very Reverend the Principal,
analogue, if not homologue, of the Principals of King’s College, than
the Rector, lineal representative of the ancient monarchs of the
University, though now, little more than a “king of shreds and patches.”

Do not suppose that, in thus briefly tracing the process of University
metamorphosis, I have had any intention of quarrelling with its
results. Practically, it seems to me that the broad changes effected in
1858 have given the Scottish Universities a very liberal constitution,
with as much real approximation to the primitive state of things as
is at all desirable. If your fat kine have eaten the lean, they have
not lain down to chew the cud ever since. The Scottish Universities,
like the English, have diverged widely enough from their primitive
model; but I cannot help thinking that the northern form has remained
more faithful to its original, not only in constitution, but, what is
more to the purpose, in view of the cry for change, in the practical
application of the endowments connected with it.

In Aberdeen, these endowments are numerous, but so small that, taken
altogether, they are not equal to the revenue of a single third-rate
English college. They are scholarships, not fellowships; aids to
do work—not rewards for such work as it lies within the reach of
an ordinary, or even an extraordinary, young man to do. You do not
think that passing a respectable examination is a fair equivalent
for an income, such as many a gray-headed veteran, or clergyman,
would envy; and which is larger than the endowment of many Regius
chairs. You do not care to make your University a school of manners
for the rich; of sports for the athletic; or a hot-bed of high-fed,
hypercritical refinement, more destructive to vigour and originality
than are starvation and oppression. No; your little Bursaries of ten
and twenty (I believe even fifty) pounds a year, enable any boy who
has shown ability in the course of his education in those remarkable
primary schools, which have made Scotland the power she is, to obtain
the highest culture the country can give him; and when he is armed and
equipped, his Spartan Alma Mater tells him that, so far, he has had his
wages for his work, and that he may go and earn the rest.

When I think of the host of pleasant, monied, well-bred young
gentlemen, who do a little learning and much boating by Cam and Isis,
the vision is a pleasant one; and, as a patriot, I rejoice that the
youth of the upper and richer classes of the nation receive a wholesome
and a manly training, however small may be the modicum of knowledge
they gather, in the intervals of this, their serious business. I admit,
to the full, the social and political value of that training. But, when
I proceed to consider that these young men may be said to represent
the great bulk of what the Colleges have to show for their enormous
wealth, plus, at least, a hundred and fifty pounds a year apiece which
each undergraduate costs his parents or guardians, I feel inclined
to ask, whether the rate-in-aid of the education of the wealthy and
professional classes, thus levied on the resources of the community,
is not, after all, a little heavy? And, still further, I am tempted
to inquire what has become of the indigent scholars, the sons of the
masses of the people whose daily labour just suffices to meet their
daily wants, for whose benefit these rich foundations were largely,
if not mainly, instituted? It seems as if Pharaoh’s dream had been
rigorously carried out, and that even the fat scholar has eaten the
lean one. And when I turn from this picture to the no less real vision
of many a brave and frugal Scotch boy, spending his summer in hard
manual labour, that he may have the privilege of wending his way in
autumn to this University, with a bag of oatmeal, ten pounds in his
pocket, and his own stout heart to depend upon through the northern
winter; not bent on seeking

  “The bubble reputation at the cannon’s mouth,”

but determined to wring knowledge from the hard hands of penury; when
I see him win through all such outward obstacles to positions of wide
usefulness and well-earned fame; I cannot but think that, in essence,
Aberdeen has departed but little from the primitive intention of the
founders of Universities, and that the spirit of reform has so much to
do on the other side of the Border, that it may be long before he has
leisure to look this way.

As compared with other actual Universities, then, Aberdeen, may,
perhaps, be well satisfied with itself. But do not think me an
impracticable dreamer, if I ask you not to rest and be thankful in
this state of satisfaction; if I ask you to consider awhile, how this
actual good stands related to that ideal better, towards which both men
and institutions must progress, if they would not retrograde.

In an ideal University, as I conceive it, a man should be able to
obtain instruction in all forms of knowledge, and discipline in the
use of all the methods by which knowledge is obtained. In such an
University, the force of living example should fire the student with a
noble ambition to emulate the learning of learned men, and to follow
in the footsteps of the explorers of new fields of knowledge. And the
very air he breathes should be charged with that enthusiasm for truth,
that fanaticism of veracity, which is a greater possession than much
learning; a nobler gift than the power of increasing knowledge; by
so much greater and nobler than these, as the moral nature of man is
greater than the intellectual; for veracity is the heart of morality.

But the man who is all morality and intellect, although he may be good
and even great, is, after all, only half a man. There is beauty in the
moral world and in the intellectual world; but there is also a beauty
which is neither moral nor intellectual—the beauty of the world of Art.
There are men who are devoid of the power of seeing it, as there are
men who are born deaf and blind, and the loss of those, as of these,
is simply infinite. There are others in whom it is an overpowering
passion; happy men, born with the productive, or at lowest, the
appreciative, genius of the Artist. But, in the mass of mankind,
the Æsthetic faculty, like the reasoning power and the moral sense,
needs to be roused, directed, and cultivated; and I know not why the
development of that side of his nature, through which man has access to
a perennial spring of ennobling pleasure, should be omitted from any
comprehensive scheme of University education.

All Universities recognise Literature in the sense of the old Rhetoric,
which is art incarnate in words. Some, to their credit, recognise Art
in its narrower sense, to a certain extent, and confer degrees for
proficiency in some of its branches. If there are Doctors of Music, why
should there be no Masters of Painting, of Sculpture, of Architecture?
I should like to see Professors of the Fine Arts in every University;
and instruction in some branch of their work made a part of the Arts
curriculum.

I just now expressed the opinion that, in our ideal University, a man
should be able to obtain instruction in all forms of knowledge. Now, by
“forms of knowledge” I mean the great classes of things knowable; of
which the first, in logical, though not in natural, order is knowledge
relating to the scope and limits of the mental faculties of man; a form
of knowledge which, in its positive aspect, answers pretty much to
Logic and part of Psychology, while, on its negative and critical side,
it corresponds with Metaphysics.

A second class comprehends all that knowledge which relates to
man’s welfare, so far as it is determined by his own acts, or what
we call his conduct. It answers to Moral and Religious philosophy.
Practically, it is the most directly valuable of all forms of
knowledge, but speculatively, it is limited and criticised by that
which precedes and by that which follows it in my order of enumeration.

A third class embraces knowledge of the phenomena of the Universe, as
that which lies about the individual man: and of the rules which those
phenomena are observed to follow in the order of their occurrence,
which we term the laws of Nature.

This is what ought to be called Natural Science, or Physiology, though
those terms are hopelessly diverted from such a meaning; and it
includes all exact knowledge of natural fact, whether Mathematical,
Physical, Biological, or Social.

Kant has said that the ultimate object of all knowledge is to give
replies to these three questions: What can I do? What ought I to do?
What may I hope for? The forms of knowledge which I have enumerated,
should furnish such replies as are within human reach, to the first
and second of these questions. While to the third, perhaps the wisest
answer is, “Do what you can to do what you ought, and leave hoping and
fearing alone.”

If this be a just and an exhaustive classification of the forms of
knowledge, no question as to their relative importance, or as to the
superiority of one to the other, can be seriously raised.

On the face of the matter, it is absurd to ask whether it is more
important to know the limits of one’s powers; or the ends for which
they ought to be exerted; or the conditions under which they must be
exerted. One may as well inquire which of the terms of a Rule of Three
sum one ought to know, in order to get a trustworthy result. Practical
life is such a sum, in which your duty multiplied into your capacity,
and divided by your circumstances, gives you the fourth term in the
proportion, which is your deserts, with great accuracy. All agree, I
take it, that men ought to have these three kinds of knowledge. The
so-called “conflict of studies” turns upon the question of how they may
best be obtained.

The founders of Universities held the theory that the Scriptures and
Aristotle taken together, the latter being limited by the former,
contained all knowledge worth having, and that the business of
philosophy was to interpret and co-ordinate these two. I imagine
that in the twelfth century this was a very fair conclusion from
known facts. Nowhere in the world, in those days, was there such an
encyclopædia of knowledge of all three classes, as is to be found in
those writings. The scholastic philosophy is a wonderful monument of
the patience and ingenuity with which the human mind toiled to build up
a logically consistent theory of the Universe, out of such materials.
And that philosophy is by no means dead and buried, as many vainly
suppose. On the contrary, numbers of men of no mean learning and
accomplishment, and sometimes of rare power and subtlety of thought,
hold by it as the best theory of things which has yet been stated. And,
what is still more remarkable, men who speak the language of modern
philosophy, nevertheless think the thoughts of the schoolmen. “The
voice is the voice of Jacob, but the hands are the hands of Esau.”
Every day I hear “Cause,” “Law,” “Force,” “Vitality,” spoken of as
entities, by people who can enjoy Swift’s joke about the meat-roasting
quality of the smoke-jack, and comfort themselves with the reflection
that they are not even as those benighted schoolmen.

Well, this great system had its day, and then it was sapped and mined
by two influences. The first was the study of classical literature,
which familiarised men with methods of philosophising; with conceptions
of the highest Good; with ideas of the order of Nature; with notions of
Literary and Historical Criticism; and, above all, with visions of Art,
of a kind which not only would not fit into the scholastic scheme, but
showed them a pre-Christian, and indeed altogether un-Christian world,
of such grandeur and beauty that they ceased to think of any other.
They were as men who had kissed the Fairy Queen, and wandering with her
in the dim loveliness of the underworld, cared not to return to the
familiar ways of home and fatherland, though they lay, at arm’s length,
overhead. Cardinals were more familiar with Virgil than with Isaiah;
and Popes laboured, with great success, to re-paganise Rome.

The second influence was the slow, but sure, growth of the physical
sciences. It was discovered that some results of speculative thought,
of immense practical and theoretical importance, can be verified by
observation; and are always true, however severely they may be tested.
Here, at any rate, was knowledge, to the certainty of which no
authority could add, or take away, one jot or tittle, and to which the
tradition of a thousand years was as insignificant as the hearsay of
yesterday. To the scholastic system, the study of classical literature
might be inconvenient and distracting, but it was possible to hope that
it could be kept within bounds. Physical science, on the other hand,
was an irreconcilable enemy, to be excluded at all hazards. The College
of Cardinals has not distinguished itself in Physics or Physiology; and
no Pope has, as yet, set up public laboratories in the Vatican.

People do not always formulate the beliefs on which they act. The
instinct of fear and dislike is quicker than the reasoning process;
and I suspect that, taken in conjunction with some other causes, such
instinctive aversion is at the bottom of the long exclusion of any
serious discipline in the physical sciences from the general curriculum
of Universities; while, on the other hand, classical literature has
been gradually made the backbone of the Arts course.

I am ashamed to repeat here what I have said elsewhere, in season
and out of season, respecting the value of Science as knowledge and
discipline. But the other day I met with some passages in the Address
to another Scottish University, of a great thinker, recently lost to
us, which express so fully, and yet so tersely, the truth in this
matter, that I am fain to quote them:—

“To question all things;—never to turn away from any difficulty;
to accept no doctrine either from ourselves or from other people
without a rigid scrutiny by negative criticism; letting no fallacy,
or incoherence, or confusion of thought step by unperceived; above
all, to insist upon having the meaning of a word clearly understood
before using it, and the meaning of a proposition before assenting
to it;—these are the lessons we learn” from workers in Science.
“With all this vigorous management of the negative element, they
inspire no scepticism about the reality of truth or indifference to
its pursuit. The noblest enthusiasm, both for the search after truth
and for applying it to its highest uses, pervades those writers.”
“In cultivating, therefore,” science as an essential ingredient in
education, “we are all the while laying an admirable foundation for
ethical and philosophical culture.”[5]

The passages I have quoted were uttered by John Stuart Mill; but you
cannot hear inverted commas, and it is therefore right that I should
add, without delay, that I have taken the liberty of substituting
“workers in science” for “ancient dialecticians,” and “Science as an
essential ingredient in education” for “the ancient languages as our
best literary education.” Mill did, in fact, deliver a noble panegyric
upon classical studies. I do not doubt its justice, nor presume to
question its wisdom. But I venture to maintain that no wise or just
judge, who has a knowledge of the facts, will hesitate to say that it
applies with equal force to scientific training.

But it is only fair to the Scottish Universities to point out that
they have long understood the value of Science as a branch of general
education. I observe, with the greatest satisfaction, that candidates
for the degree of Master of Arts in this University are required to
have a knowledge, not only of Mental and Moral Philosophy, and of
Mathematics and Natural Philosophy, but of Natural History, in addition
to the ordinary Latin and Greek course; and that a candidate may take
honours in these subjects and in Chemistry.

I do not know what the requirements of your examiners may be, but I
sincerely trust they are not satisfied with a mere book knowledge of
these matters. For my own part, I would not raise a finger, if I could
thereby introduce mere book work in science into every Arts curriculum
in the country. Let those who want to study books devote themselves
to Literature, in which we have the perfection of books, both as to
substance and as to form. If I may paraphrase Hobbes’s well-known
aphorism, I would say that “books are the money of Literature, but only
the counters of Science,” Science (in the sense in which I now use the
term) being the knowledge of fact, of which every verbal description
is but an incomplete and symbolic expression. And be assured that no
teaching of science is worth anything, as a mental discipline, which is
not based upon direct perception of the facts, and practical exercise
of the observing and logical faculties upon them. Even in such a simple
matter as the mere comprehension of form, ask the most practised and
widely informed anatomist what is the difference between his knowledge
of a structure which he has read about, and his knowledge of the same
structure when he has seen it for himself; and he will tell you that
the two things are not comparable—the difference is infinite. Thus I
am very strongly inclined to agree with some learned school-masters
who say that, in their experience, the teaching of science is all
waste time. As they teach it, I have no doubt it is. But to teach it
otherwise, requires an amount of personal labour and a development of
means and appliances, which must strike horror and dismay into a man
accustomed to mere book work; and who has been in the habit of teaching
a class of fifty without much strain upon his energies. And this is one
of the real difficulties in the way of the introduction of physical
science into the ordinary University course, to which I have alluded.
It is a difficulty which will not be overcome, until years of patient
study have organised scientific teaching as well as, or I hope better
than, classical teaching has been organised hitherto.

A little while ago, I ventured to hint a doubt as to the perfection
of some of the arrangements in the ancient Universities of England;
but, in their provision for giving instruction in Science as such,
and without direct reference to any of its practical applications,
they have set a brilliant example. Within the last twenty years,
Oxford alone has sunk more than a hundred and twenty thousand pounds
in building and furnishing Physical, Chemical, and Physiological
Laboratories, and a magnificent Museum, arranged with an almost
luxurious regard for the needs of the student. Cambridge, less rich,
but aided by the munificence of her Chancellor, is taking the same
course; and, in a few years, it will be for no lack of the means and
appliances of sound teaching, if the mass of English University men
remain in their present state of barbarous ignorance of even the
rudiments of scientific culture.

Yet another step needs to be made before Science can be said to have
taken its proper place in the Universities. That is its recognition
as a Faculty, or branch of study demanding recognition and special
organisation, on account of its bearing on the wants of mankind. The
Faculties of Theology, Law, and Medicine, are technical schools,
intended to equip men who have received general culture, with the
special knowledge which is needed for the proper performance of the
duties of clergymen, lawyers, and medical practitioners.

When the material well-being of the country depended upon rude pasture
and agriculture, and still ruder mining; in the days when all the
innumerable applications of the principles of physical science to
practical purposes were non-existent even as dreams; days which men
living may have heard their fathers speak of; what little physical
science could be seen to bear directly upon human life, lay within the
province of Medicine. Medicine was the foster-mother of Chemistry,
because it has to do with the preparation of drugs and the detection
of poisons; of Botany, because it enabled the physician to recognise
medicinal herbs; of Comparative Anatomy and Physiology, because the man
who studied Human Anatomy and Physiology for purely medical purposes
was led to extend his studies to the rest of the animal world.

Within my recollection, the only way in which a student could obtain
anything like a training in Physical Science, was by attending the
lectures of the Professors of Physical and Natural Science attached to
the Medical Schools. But, in the course of the last thirty years, both
foster-mother and child have grown so big, that they threaten not only
to crush one another, but to press the very life out of the unhappy
student who enters the nursery; to the great detriment of all three.

I speak in the presence of those who know practically what medical
education is; for I may assume that a large proportion of my hearers
are more or less advanced students of medicine. I appeal to the most
industrious and conscientious among you, to those who are most deeply
penetrated with a sense of the extremely serious responsibilities which
attach to the calling of a medical practitioner, when I ask whether,
out of the four years which you devote to your studies, you ought to
spare even so much as an hour for any work which does not tend directly
to fit you for your duties?

Consider what that work is. Its foundation is a sound and practical
acquaintance with the structure of the human organism, and with the
modes and conditions of its action in health. I say a sound and
practical acquaintance, to guard against the supposition that my
intention is to suggest that you ought all to be minute anatomists and
accomplished physiologists. The devotion of your whole four years to
Anatomy and Physiology alone, would be totally insufficient to attain
that end. What I mean is, the sort of practical, familiar, finger-end
knowledge which a watchmaker has of a watch, and which you expect that
craftsman, as an honest man, to have, when you entrust a watch that
goes badly, to him. It is a kind of knowledge which is to be acquired,
not in the lecture-room, nor in the library, but in the dissecting-room
and the laboratory. It is to be had, not by sharing your attention
between these and sundry other subjects, but by concentrating your
minds, week after week, and month after month, six or seven hours a
day, upon all the complexities of organ and function, until each of the
greater truths of anatomy and physiology has become an organic part of
your minds—until you would know them if you were roused and questioned
in the middle of the night, as a man knows the geography of his native
place and the daily life of his home. That is the sort of knowledge
which, once obtained, is a life-long possession. Other occupations may
fill your minds—it may grow dim, and seem to be forgotten—but there it
is, like the inscription on a battered and defaced coin, which comes
out when you warm it.

If I had the power to remodel Medical Education, the first two years of
the medical curriculum should be devoted to nothing but such thorough
study of Anatomy and Physiology, with Physiological Chemistry and
Physics; the student should then pass a real, practical examination in
these subjects; and, having gone through that ordeal satisfactorily,
he should be troubled no more with them. His whole mind should then be
given with equal intentness, to Therapeutics, in its broadest sense,
to Practical Medicine and to Surgery, with instruction in Hygiene and
in Medical Jurisprudence; and of these subjects only—surely there are
enough of them—should he be required to show a knowledge in his final
examination.

I cannot claim any special property in this theory of what the medical
curriculum should be, for I find that views, more or less closely
approximating these, are held by all who have seriously considered the
very grave and pressing question of Medical Reform; and have, indeed,
been carried into practice, to some extent, by the most enlightened
Examining Boards. I have heard but two kinds of objections to them.
There is, first, the objection of vested interests, which I will not
deal with here, because I want to make myself as pleasant as I can, and
no discussions are so unpleasant as those which turn on such points.
And there is, secondly, the much more respectable objection, which
takes the general form of the reproach that, in thus limiting the
curriculum, we are seeking to narrow it. We are told that the medical
man ought to be a person of good education and general information,
if his profession is to hold its own among other professions; that
he ought to know Botany, or else, if he goes abroad, he will not be
able to tell poisonous fruits from edible ones; that he ought to
know drugs, as a druggist knows them, or he will not be able to tell
sham bark and senna from the real articles; that he ought to know
Zoology, because—well, I really have never been able to learn exactly
why he is to be expected to know zoology. There is, indeed, a popular
superstition, that doctors know all about things that are queer or
nasty to the general mind, and may, therefore, be reasonably expected
to know the “barbarous binomials” applicable to snakes, snails, and
slugs; an amount of information with which the general mind is usually
completely satisfied. And there is a scientific superstition that
Physiology is largely aided by Comparative Anatomy—a superstition
which, like most superstitions, once had a grain of truth at bottom;
but the grain has become homœopathic, since Physiology took its modern
experimental development, and became what it is now, the application
of the principles of Physics and Chemistry to the elucidation of the
phenomena of life.

I hold as strongly as any one can do, that the medical practitioner
ought to be a person of education and good general culture; but I
also hold by the old theory of a Faculty, that a man should have his
general culture before he devotes himself to the special studies of
that Faculty; and I venture to maintain, that, if the general culture
obtained in the Faculty of Arts were what it ought to be, the student
would have quite as much knowledge of the fundamental principles of
Physics, of Chemistry, and of Biology, as he needs, before he commenced
his special medical studies.

Moreover, I would urge, that a thorough study of Human Physiology is,
in itself, an education broader and more comprehensive than much that
passes under that name. There is no side of the intellect which it does
not call into play, no region of human knowledge into which either its
roots, or its branches, do not extend; like the Atlantic between the
Old and the New Worlds, its waves wash the shores of the two worlds
of matter and of mind; its tributary streams flow from both; through
its waters, as yet unfurrowed by the keel of any Columbus, lies the
road, if such there be, from the one to the other; far away from that
North-west Passage of mere speculation, in which so many brave souls
have been hopelessly frozen up.

But whether I am right or wrong about all this, the patent fact of the
limitation of time remains. As the song runs:—

     “If a man could be sure
      That his life would endure
  For the space of a thousand long years——”

he might do a number of things not practicable under present
conditions. Methuselah might, with much propriety, have taken half a
century to get his doctor’s degree; and might, very fairly, have been
required to pass a practical examination upon the contents of the
British Museum, before commencing practice as a promising young fellow
of two hundred, or thereabouts. But you have four years to do your
work in, and are turned loose, to save or slay, at two or three and
twenty.

Now, I put it to you, whether you think that, when you come down to
the realities of life—when you stand by the sick-bed, racking your
brains for the principles which shall furnish you with the means of
interpreting symptoms, and forming a rational theory of the condition
of your patient, it will be satisfactory for you to find that those
principles are not there—although, to use the examination slang which
is unfortunately too familiar to me, you can quite easily “give
an account of the leading peculiarities of the _Marsupialia_,” or
“enumerate the chief characters of the _Compositæ_,” or “state the
class and order of the animal from which Castoreum is obtained.”

I really do not think that state of things will be satisfactory
to you; I am very sure it will not be so to your patient. Indeed,
I am so narrow-minded myself, that if I had to choose between two
physicians—one who did not know whether a whale is a fish or not, and
could not tell gentian from ginger, but did understand the applications
of the institutes of medicine to his art; while the other, like
Talleyrand’s doctor, “knew everything, even a little physic”—with all
my love for breadth of culture, I should assuredly consult the former.

It is not pleasant to incur the suspicion of an inclination to injure
or depreciate particular branches of knowledge. But the fact that
one of those which I should have no hesitation in excluding from the
medical curriculum, is that to which my own life has been specially
devoted, should, at any rate, defend me from the suspicion of being
urged to this course by any but the very gravest considerations of the
public welfare.

And I should like, further, to call your attention to the important
circumstance that, in thus proposing the exclusion of the study of such
branches of knowledge as Zoology and Botany, from those compulsory upon
the medical student, I am not, for a moment, suggesting their exclusion
from the University. I think that sound and practical instruction in
the elementary facts and broad principles of Biology should form part
of the Arts Curriculum: and here, happily, my theory is in entire
accordance with your practice. Moreover, as I have already said, I have
no sort of doubt that, in view of the relation of Physical Science
to the practical life of the present day, it has the same right as
Theology, Law, and Medicine, to a Faculty of its own in which men shall
be trained to be professional men of science. It may be doubted whether
Universities are the places for technical schools of Engineering, or
Applied Chemistry, or Agriculture. But there can surely be little
question, that instruction in the branches of Science which lie at the
foundation of these Arts, of a far more advanced and special character
than could, with any propriety, be included in the ordinary Arts
Curriculum, ought to be obtainable by means of a duly organised Faculty
of Science in every University.

The establishment of such a Faculty would have the additional advantage
of providing, in some measure, for one of the greatest wants of our
time and country. I mean the proper support and encouragement of
original research.

The other day, an emphatic friend of mine committed himself to the
opinion that, in England, it is better for a man’s worldly prospects
to be a drunkard, than to be smitten with the divine dipsomania of the
original investigator. I am inclined to think he was not far wrong.
And, be it observed, that the question is not, whether such a man shall
be able to make as much out of his abilities as his brother, of like
ability, who goes into Law, or Engineering, or Commerce; it is not a
question of “maintaining a due number of saddle horses,” as George
Eliot somewhere puts it—it is a question of living or starving.

If a student of my own subject shows power and originality, I dare not
advise him to adopt a scientific career; for, supposing he is able to
maintain himself until he has attained distinction, I cannot give him
the assurance that any amount of proficiency in the Biological Sciences
will be convertible into, even the most modest, bread and cheese.
And I believe that the case is as bad, or perhaps worse, with other
branches of Science. In this respect Britain, whose immense wealth
and prosperity hang upon the thread of Applied Science, is far behind
France, and infinitely behind Germany.

And the worst of it is, that it is very difficult to see one’s way to
any immediate remedy for this state of affairs which shall be free from
a tendency to become worse than the disease.

Great schemes for the Endowment of Research have been proposed. It has
been suggested, that Laboratories for all branches of Physical Science,
provided with every apparatus needed by the investigator, shall be
established by the State: and shall be accessible, under due conditions
and regulations, to all properly qualified persons. I see no objection
to the principle of such a proposal. If it be legitimate to spend great
sums of money on public Libraries and public collections of Painting
and Sculpture, in aid of the man of letters, or the Artist, or for the
mere sake of affording pleasure to the general public, I apprehend that
it cannot be illegitimate to do as much for the promotion of scientific
investigation. To take the lowest ground, as a mere investment of
money, the latter is likely to be much more immediately profitable. To
my mind, the difficulty in the way of such schemes is not theoretical,
but practical. Given the laboratories, how are the investigators to be
maintained? What career is open to those who have been thus encouraged
to leave bread-winning pursuits? If they are to be provided for by
endowment, we come back to the College Fellowship system, the results
of which, for Literature, have not been so brilliant that one would
wish to see it extended to Science; unless some much better securities,
than at present exist, can be taken that it will foster real work.
You know that among the Bees, it depends on the kind of cell in which
the egg is deposited, and the quantity and quality of food which is
supplied to the grub, whether it shall turn out a busy little worker
or a big idle queen. And, in the human hive, the cells of the endowed
larvæ are always tending to enlarge, and their food to improve, until
we get queens, beautiful to behold, but which gather no honey and build
no comb.

I do not say that these difficulties may not be overcome, but their
gravity is not to be lightly estimated.

In the meanwhile, there is one step in the direction of the endowment
of research which is free from such objections. It is possible to place
the scientific inquirer in a position in which he shall have ample
leisure and opportunity for original work, and yet shall give a fair
and tangible equivalent for those privileges. The establishment of a
Faculty of Science in every University, implies that of a corresponding
number of Professorial chairs, the incumbents of which need not be
so burdened with teaching as to deprive them of ample leisure for
original work. I do not think that it is any impediment to an original
investigator to have to devote a moderate portion of his time to
lecturing, or superintending practical instruction. On the contrary,
I think it may be, and often is, a benefit to be obliged to take a
comprehensive survey of your subject; or to bring your results to a
point, and give them, as it were, a tangible objective existence. The
besetting sins of the investigator are two: the one is the desire to
put aside a subject, the general bearings of which he has mastered
himself, and pass on to something which has the attraction of novelty;
and the other, the desire for too much perfection, which leads him to

  “Add and alter many times,
   Till all be ripe and rotten;”

to spend the energies which should be reserved for action, in whitening
the decks and polishing the guns.

The obligation to produce results for the instruction of others, seems
to me to be a more effectual check on these tendencies, than even the
love of usefulness or the ambition for fame.

But supposing the Professorial forces of our University to be
duly organised, there remains an important question, relating
to the teaching power, to be considered. Is the Professorial
system—the system, I mean, of teaching in the lecture-room alone,
and leaving the student to find his own way when he is outside the
lecture-room—adequate to the wants of learners? In answering this
question, I confine myself to my own province, and I venture to
reply for Physical Science, assuredly and undoubtedly, No. As I have
already intimated, practical work in the Laboratory is absolutely
indispensable, and that practical work must be guided and superintended
by a sufficient staff of Demonstrators, who are for Science what Tutors
are for other branches of study. And there must be a good supply of
such Demonstrators. I doubt if the practical work of more than twenty
students can be properly superintended by one Demonstrator. If we
take the working day at six hours, that is less than twenty minutes
apiece—not a very large allowance of time for helping a dull man, for
correcting an inaccurate one, or even for making an intelligent student
clearly apprehend what he is about. And, no doubt, the supplying of
a proper amount of this tutorial, practical teaching, is a difficulty
in the way of giving proper instruction in Physical Science in such
Universities as that of Aberdeen, which are devoid of endowments; and,
unlike the English Universities, have no moral claim on the funds of
richly endowed bodies to supply their wants.

Examination—thorough, searching examination—is an indispensable
accompaniment of teaching; but I am almost inclined to commit myself
to the very heterodox proposition that it is a necessary evil. I am a
very old Examiner, having, for some twenty years past, been occupied
with examinations on a considerable scale, of all sorts and conditions
of men, and women too,—from the boys and girls of elementary schools
to the candidates for Honours and Fellowships in the Universities. I
will not say that, in this case as in so many others, the adage, that
familiarity breeds contempt, holds good; but my admiration for the
existing system of examination and its products, does not wax warmer
as I see more of it. Examination, like fire, is a good servant, but a
bad master; and there seems to me to be some danger of its becoming our
master. I by no means stand alone in this opinion. Experienced friends
of mine do not hesitate to say that students whose career they watch,
appear to them to become deteriorated by the constant effort to pass
this or that examination, just as we hear of men’s brains becoming
affected by the daily necessity of catching a train. They work to pass,
not to know; and outraged Science takes her revenge. They do pass,
and they don’t know. I have passed sundry examinations in my time, not
without credit, and I confess I am ashamed to think how very little
real knowledge underlay the torrent of stuff which I was able to pour
out on paper. In fact, that which examination, as ordinarily conducted,
tests, is simply a man’s power of work under stimulus, and his capacity
for rapidly and clearly producing that which, for the time, he has got
into his mind. Now, these faculties are by no means to be despised.
They are of great value in practical life, and are the making of many
an advocate, and of many a so-called statesman. But in the pursuit of
truth, scientific or other, they count for very little, unless they are
supplemented by that long-continued, patient “intending of the mind,”
as Newton phrased it, which makes very little show in Examinations. I
imagine that an Examiner who knows his students personally, must not
unfrequently have found himself in the position of finding A’s paper
better than B’s, though his own judgment tells him, quite clearly, that
B is the man who has the larger share of genuine capacity.

Again, there is a fallacy about Examiners. It is commonly supposed that
any one who knows a subject is competent to teach it; and no one seems
to doubt that any one who knows a subject is competent to examine in
it. I believe both these opinions to be serious mistakes: the latter,
perhaps, the more serious of the two. In the first place, I do not
believe that any one who is not, or has not been, a teacher is really
qualified to examine advanced students. And in the second place,
Examination is an Art, and a difficult one, which has to be learned
like all other arts.

Beginners always set too difficult questions—partly because they are
afraid of being suspected of ignorance if they set easy ones, and
partly from not understanding their business. Suppose that you want to
test the relative physical strength of a score of young men. You do not
put a hundredweight down before them, and tell each to swing it round.
If you do, half of them won’t be able to lift it at all, and only one
or two will be able to perform the task. You must give them half a
hundredweight, and see how they manœuvre that, if you want to form any
estimate of the muscular strength of each. So, a practised Examiner
will seek for information respecting the mental vigour and training of
candidates from the way in which they deal with questions easy enough
to let reason, memory, and method have free play.

No doubt, a great deal is to be done by the careful selection of
Examiners, and by the copious introduction of practical work, to
remove the evils inseparable from examination; but, under the best of
circumstances, I believe that examination will remain but an imperfect
test of knowledge, and a still more imperfect test of capacity, while
it tells next to nothing about a man’s power as an investigator.

There is much to be said in favour of restricting the highest degrees
in each Faculty, to those who have shown evidence of such original
power, by prosecuting a research under the eye of the Professor in
whose province it lies; or, at any rate, under conditions which shall
afford satisfactory proof that the work is theirs. The notion may sound
revolutionary, but it is really very old; for, I take it, that it lies
at the bottom of that presentation of a thesis by the candidate for a
doctorate, which has now, too often, become little better than a matter
of form.


Thus far, I have endeavoured to lay before you, in a too brief and
imperfect manner, my views respecting the teaching half—the Magistri
and Regentes—of the University of the Future. Now let me turn to the
learning half—the Scholares.

If the Universities are to be the sanctuaries of the highest culture of
the country, those who would enter that sanctuary, must not come with
unwashed hands. If the good seed is to yield its hundredfold harvest,
it must not be scattered amidst the stones of ignorance, or the tares
of undisciplined indolence and wantonness. On the contrary, the soil
must have been carefully prepared, and the Professor should find that
the operations of clod-crushing, draining, and weeding, and even a good
deal of planting, have been done by the Schoolmaster.

That is exactly what the Professor does not find in any University in
the three Kingdoms that I can hear of—the reason of which state of
things lies in the extremely faulty organisation of the majority of
secondary Schools. Students come to the Universities ill-prepared in
classics and mathematics, not at all prepared in anything else; and
half their time is spent in learning that which they ought to have
known when they came.

I sometimes hear it said that the Scottish Universities differ from
the English, in being to a much greater extent places of comparatively
elementary education for a younger class of students. But it would seem
doubtful if any great difference of this kind really exists; for a high
authority, himself Head of an English College, has solemnly affirmed
that: “Elementary teaching of youths under twenty is now the only
function performed by the University;” and that Colleges are “boarding
schools in which the elements of the learned languages are taught to
youths.”[6]

This is not the first time that I have quoted those remarkable
assertions. I should like to engrave them in public view, for they
have not been refuted; and I am convinced that if their import is once
clearly apprehended, they will play no mean part when the question of
University reorganisation, with a view to practical measures, comes
on for discussion. You are not responsible for this anomalous state
of affairs now; but, as you pass into active life and acquire the
political influence to which your education and your position should
entitle you, you will become responsible for it, unless each in his
sphere does his best to alter it, by insisting on the improvement of
secondary Schools.

Your present responsibility is of another, though not less serious,
kind. Institutions do not make men, any more than organisation makes
life; and even the ideal University we have been dreaming about will be
but a superior piece of mechanism, unless each student strive after the
ideal of the Scholar. And that ideal, it seems to me, has never been
better embodied than by the great Poet, who, though lapped in luxury,
the favourite of a Court, and the idol of his countrymen, remained
through all the length of his honoured years a Scholar in Art, in
Science, and in Life.

  “Would’st shape a noble life? Then cast
  No backward glances towards the past:
  And though somewhat be lost and gone,
  Yet do thou act as one new-born.
  What each day needs, that shalt thou ask;
  Each day will set its proper task.
  Give other’s work just share of praise;
  Not of thine own the merits raise.
  Beware no fellow man thou hate:
  And so in God’s hands leave thy fate.”[7]




III.

TECHNICAL EDUCATION.


Any candid observer of the phenomena of modern society will readily
admit that bores must be classed among the enemies of the human race;
and a little consideration will probably lead him to the further
admission, that no species of that extensive genus of noxious creatures
is more objectionable than the educational bore. Convinced as I am of
the truth of this great social generalisation, it is not without a
certain trepidation that I venture to address you on an educational
topic. For, in the course of the last ten years, to go back no farther,
I am afraid to say how often I have ventured to speak of education,
from that given in the primary schools to that which is to be had in
the universities and medical colleges; indeed, the only part of this
wide region into which, as yet, I have not adventured is that into
which I propose to intrude to-day.

Thus, I cannot but be aware that I am dangerously near becoming the
thing which all men fear and fly. But I have deliberately elected to
run the risk. For when you did me the honour to ask me to address you,
an unexpected circumstance had led me to occupy myself seriously with
the question of technical education; and I had acquired the conviction
that there are few subjects respecting which it is more important for
all classes of the community to have clear and just ideas than this;
while, certainly, there is none which is more deserving of attention by
the Working Men’s Club and Institute Union.

It is not for me to express an opinion whether the considerations,
which I am about to submit to you, will be proved by experience to be
just or not; but I will do my best to make them clear. Among the many
good things to be found in Lord Bacon’s works, none is more full of
wisdom than the saying that “truth more easily comes out of error than
out of confusion.” Clear and consecutive wrong-thinking is the next
best thing to right-thinking; so that, if I succeed in clearing your
ideas on this topic, I shall have wasted neither your time nor my own.

“Technical education,” in the sense in which the term is ordinarily
used, and in which I am now employing it, means that sort of education
which is specially adapted to the needs of men whose business in
life it is to pursue some kind of handicraft; it is, in fact, a fine
Greco-Latin equivalent for what in good vernacular English would be
called “the teaching of handicrafts.” And probably, at this stage of
our progress, it may occur to many of you to think of the story of the
cobbler and his last, and to say to yourselves, though you will be too
polite to put the question openly to me, What does the speaker know
practically about this matter? What is his handicraft? I think the
question is a very proper one, and unless I were prepared to answer it,
I hope satisfactorily, I should have chosen some other theme.

The fact is, I am, and have been, any time these thirty years, a man
who works with his hands—a handicraftsman. I do not say this in the
broadly metaphorical sense in which fine gentlemen, with all the
delicacy of Agag about them, trip to the hustings about election time,
and protest that they too are working men. I really mean my words to be
taken in their direct, literal, and straightforward sense. In fact, if
the most nimble-fingered watchmaker among you will come to my workshop,
he may set me to put a watch together, and I will set him to dissect,
say, a blackbeetle’s nerves. I do not wish to vaunt, but I am inclined
to think that I shall manage my job to his satisfaction sooner than he
will do his piece of work to mine.

In truth, anatomy, which is my handicraft, is one of the most difficult
kinds of mechanical labour, involving, as it does, not only lightness
and dexterity of hand, but sharp eyes and endless patience. And you
must not suppose that my particular branch of science is especially
distinguished for the demand it makes upon skill in manipulation. A
similar requirement is made upon all students of physical science.
The astronomer, the electrician, the chemist, the mineralogist, the
botanist, are constantly called upon to perform manual operations of
exceeding delicacy. The progress of all branches of physical science
depends upon observation, or on that artificial observation which is
termed experiment, of one kind or another; and, the farther we advance,
the more practical difficulties surround the investigation of the
conditions of the problems offered to us; so that mobile and yet steady
hands, guided by clear vision, are more and more in request in the
workshops of science.

Indeed, it has struck me that one of the grounds of that sympathy
between the handicraftsmen of this country and the men of science, by
which it has so often been my good fortune to profit, may, perhaps, lie
here. You feel and we feel that, among the so-called learned folks, we
alone are brought into contact with tangible facts in the way that you
are. You know well enough that it is one thing to write a history of
chairs in general, or to address a poem to a throne, or to speculate
about the occult powers of the chair of St. Peter; and quite another
thing to make with your own hands a veritable chair, that will stand
fair and square, and afford a safe and satisfactory resting-place to a
frame of sensitiveness and solidity.

So it is with us, when we look out from our scientific handicrafts
upon the doings of our learned brethren, whose work is untrammelled
by anything “base and mechanical,” as handicrafts used to be called
when the world was younger, and, in some respects, less wise than
now. We take the greatest interest in their pursuits; we are edified
by their histories and are charmed with their poems, which sometimes
illustrate so remarkably the powers of man’s imagination; some of us
admire and even humbly try to follow them in their high philosophical
excursions, though we know the risk of being snubbed by the inquiry
whether grovelling dissectors of monkeys and blackbeetles can hope
to enter into the empyreal kingdom of speculation. But still we feel
that our business is different; humbler if you will, though the
diminution of dignity is, perhaps, compensated by the increase of
reality; and that we, like you, have to get our work done in a region
where little avails, if the power of dealing with practical tangible
facts is wanting. You know that clever talk touching joinery will not
make a chair; and I know that it is of about as much value in the
physical sciences. Mother Nature is serenely obdurate to honeyed words;
only those who understand the ways of things, and can silently and
effectually handle them, get any good out of her.


And now, having, as I hope, justified my assumption of a place among
handicraftsmen, and put myself right with you as to my qualification,
from practical knowledge, to speak about technical education, I will
proceed to lay before you the results of my experience as a teacher of
a handicraft, and tell you what sort of education I should think best
adapted for a boy whom one wanted to make a professional anatomist.

I should say, in the first place, let him have a good English
elementary education. I do not mean that he shall be able to pass
in such and such a standard—that may or may not be an equivalent
expression—but that his teaching shall have been such as to have given
him command of the common implements of learning and to have created a
desire for the things of the understanding.

Further, I should like him to know the elements of physical science,
and especially of physics and chemistry, and I should take care that
this elementary knowledge was real. I should like my aspirant to
be able to read a scientific treatise in Latin, French, or German,
because an enormous amount of anatomical knowledge is locked up in
those languages. And especially, I should require some ability to
draw—I do not mean artistically, for that is a gift which may be
cultivated but cannot be learned, but with fair accuracy. I will not
say that everybody can learn even this; for the negative development
of the faculty of drawing in some people is almost miraculous. Still
everybody, or almost everybody, can learn to write; and, as writing is
a kind of drawing, I suppose that the majority of the people who say
they cannot draw, and give copious evidence of the accuracy of their
assertion, could draw, after a fashion, if they tried. And that “after
a fashion” would be better than nothing for my purposes.

Above all things, let my imaginary pupil have preserved the freshness
and vigour of youth in his mind as well as his body. The educational
abomination of desolation of the present day is the stimulation
of young people to work at high pressure by incessant competitive
examinations. Some wise man (who probably was not an early riser)
has said of early risers in general, that they are conceited all the
forenoon and stupid all the afternoon. Now whether this is true of
early risers in the common acceptation of the word or not, I will not
pretend to say; but it is too often true of the unhappy children who
are forced to rise too early in their classes. They are conceited all
the forenoon of life, and stupid all its afternoon. The vigour and
freshness, which should have been stored up for the purposes of the
hard struggle for existence in practical life, have been washed out
of them by precocious mental debauchery—by book gluttony and lesson
bibbing. Their faculties are worn out by the strain put upon their
callow brains, and they are demoralised by worthless childish triumphs
before the real work of life begins. I have no compassion for sloth,
but youth has more need for intellectual rest than age; and the
cheerfulness, the tenacity of purpose, the power of work which make
many a successful man what he is, must often be placed to the credit,
not of his hours of industry, but to that of his hours of idleness,
in boyhood. Even the hardest worker of us all, if he has to deal with
anything above mere details, will do well, now and again, to let his
brain lie fallow for a space. The next crop of thought will certainly
be all the fuller in the ear and the weeds fewer.

This is the sort of education which I should like any one who was
going to devote himself to my handicraft to undergo. As to knowing
anything about anatomy itself, on the whole I would rather he left that
alone until he took it up seriously in my laboratory. It is hard work
enough to teach, and I should not like to have superadded to that the
possible need of unteaching.

Well, but, you will say, this is Hamlet with the Prince of Denmark left
out; your “technical education” is simply a good education, with more
attention to physical science, to drawing, and to modern languages,
than is common, and there is nothing specially technical about it.

Exactly so; that remark takes us straight to the heart of what I have
to say; which is, that, in my judgment, the preparatory education
of the handicraftsman ought to have nothing of what is ordinarily
understood by “technical” about it.

The workshop is the only real school for a handicraft. The education
which precedes that of the workshop should be entirely devoted to the
strengthening of the body, the elevation of the moral faculties, and
the cultivation of the intelligence; and, especially, to the imbuing
the mind with a broad and clear view of the laws of that natural world
with the components of which the handicraftsman will have to deal. And,
the earlier the period of life at which the handicraftsman has to enter
into actual practice of his craft, the more important is it that he
should devote the precious hours of preliminary education to things of
the mind, which have no direct and immediate bearing on his branch of
industry, though they lie at the foundation of all realities.


Now let me apply the lessons I have learned from my handicraft to
yours. If any of you were obliged to take an apprentice, I suppose
you would like to get a good healthy lad, ready and willing to learn,
handy, and with his fingers not all thumbs, as the saying goes. You
would like that he should read, write, and cipher well; and, if you
were an intelligent master, and your trade involved the application of
scientific principles, as so many trades do, you would like him to know
enough of the elementary principles of science to understand what was
going on. I suppose that, in nine trades out of ten, it would be useful
if he could draw; and many of you must have lamented your inability
to find out for yourselves what foreigners are doing or have done. So
that some knowledge of French and German might, in many cases, be very
desirable.

So it appears to me that what you want is pretty much what I want; and
the practical question is, How you are to get what you need, under the
actual limitations and conditions of life of handicraftsmen in this
country?

I think I shall have the assent both of the employers of labour and of
the employed as to one of these limitations; which is, that no scheme
of technical education is likely to be seriously entertained which will
delay the entrance of boys into working life, or prevent them from
contributing towards their own support, as early as they do at present.
Not only do I believe that any such scheme could not be carried out,
but I doubt its desirableness, even if it were practicable.

The period between childhood and manhood is full of difficulties and
dangers, under the most favourable circumstances; and, even among the
well-to-do, who can afford to surround their children with the most
favourable conditions, examples of a career ruined, before it has well
begun, are but too frequent. Moreover, those who have to live by labour
must be shaped to labour early. The colt that is left at grass too
long makes but a sorry draught-horse, though his way of life does not
bring him within the reach of artificial temptations. Perhaps the most
valuable result of all education is the ability to make yourself do the
thing you have to do, when it ought to be done, whether you like it
or not; it is the first lesson that ought to be learned; and, however
early a man’s training begins, it is probably the last lesson that he
learns thoroughly.

There is another reason, to which I have already adverted, and which
I would reiterate, why any extension of the time devoted to ordinary
school-work is undesirable. In the newly awakened zeal for education,
we run some risk of forgetting the truth that while under-instruction
is a bad thing, over-instruction may possibly be a worse.

Success in any kind of practical life is not dependent solely, or
indeed chiefly, upon knowledge. Even in the learned professions,
knowledge, alone, is of less consequence than people are apt to
suppose. And, if much expenditure of bodily energy is involved in the
day’s work, mere knowledge is of still less importance when weighed
against the probable cost of its acquirement. To do a fair day’s work
with his hands, a man needs, above all things, health, strength, and
the patience and cheerfulness which, if they do not always accompany
these blessings, can hardly in the nature of things exist without them;
to which we must add honesty of purpose and a pride in doing what is
done well.

A good handicraftsman can get on very well without genius, but he will
fare badly without a reasonable share of that which is a more useful
possession for workaday life, namely, mother-wit; and he will be all
the better for a real knowledge, however limited, of the ordinary laws
of nature, and especially of those which apply to his own business.

Instruction carried so far as to help the scholar to turn his store of
mother-wit to account, to acquire a fair amount of sound elementary
knowledge, and to use his hands and eyes; while leaving him fresh,
vigorous, and with a sense of the dignity of his own calling, whatever
it may be, if fairly and honestly pursued, cannot fail to be of
invaluable service to all those who come under its influence.

But, on the other hand, if school instruction is carried so far as to
encourage bookishness; if the ambition of the scholar is directed, not
to the gaining of knowledge, but to the being able to pass examinations
successfully; especially if encouragement is given to the mischievous
delusion that brainwork is, in itself, and apart from its quality, a
nobler or more respectable thing than handiwork—such education may be
a deadly mischief to the workman, and lead to the rapid ruin of the
industries it is intended to serve.

I know that I am expressing the opinion of some of the largest as well
as the most enlightened employers of labour, when I say that there is
a real danger that, from the extreme of no education, we may run to
the other extreme of over-education of handicraftsmen. And I apprehend
that what is true for the ordinary hand-worker is true for the foreman.
Activity, probity, knowledge of men, ready mother-wit, supplemented by
a good knowledge of the general principles involved in his business,
are the making of a good foreman. If he possess these qualities, no
amount of learning will fit him better for his position; while the
course of life and the habit of mind required for the attainment of
such learning may, in various direct and indirect ways, act as direct
disqualifications for it.

Keeping in mind, then, that the two things to be avoided are, the delay
of the entrance of boys into practical life, and the substitution
of exhausted book-worms for shrewd, handy men, in our works and
factories, let us consider what may be wisely and safely attempted in
the way of improving the education of the handicraftsman.

First, I look to the elementary schools now happily established all
over the country. I am not going to criticise or find fault with
them; on the contrary, their establishment seems to me to be the most
important and the most beneficial result of the corporate action of the
people in our day. A great deal is said of British interests just now,
but, depend upon it, that no Eastern difficulty needs our intervention
as a nation so seriously, as the putting down both the Bashi-Bazouks
of ignorance and the Cossacks of sectarianism at home. What has already
been achieved in these directions is a great thing; you must have lived
some time to know how great. An education, better in its processes,
better in its substance, than that which was accessible to the great
majority of well-to-do Britons a quarter of a century ago, is now
obtainable by every child in the land. Let any man of my age go into
an ordinary elementary school, and, unless he was unusually fortunate
in his youth, he will tell you that the educational method, the
intelligence, patience, and good temper on the teacher’s part, which
are now at the disposal of the veriest waifs and wastrels of society,
are things of which he had no experience in those costly middle-class
schools, which were so ingeniously contrived as to combine all the
evils and shortcomings of the great public schools with none of their
advantages. Many a man, whose so-called education cost a good deal of
valuable money and occupied many a year of invaluable time, leaves the
inspection of a well-ordered elementary school devoutly wishing that,
in his young days, he had had the chance of being as well taught as
these boys and girls are.

But while, in view of such an advance in general education, I willingly
obey the natural impulse to be thankful, I am not willing altogether
to rest. I want to see instruction in elementary science and in art
more thoroughly incorporated in the educational system. At present, it
is being administered by driblets, as if it were a potent medicine,
“a few drops to be taken occasionally in a teaspoon.” Every year I
notice that that earnest and untiring friend of yours and of mine,
Sir John Lubbock, stirs up the Government of the day in the House of
Commons on this subject; and also that, every year, he, and the few
members of the House of Commons, such as Mr. Playfair, who sympathise
with him, are met with expressions of warm admiration for science in
general, and reasons at large for doing nothing in particular. But now
that Mr. Forster, to whom the education of the country owes so much,
has announced his conversion to the right faith, I begin to hope that,
sooner or later, things will mend.

I have given what I believe to be a good reason for the assumption,
that the keeping at school of boys, who are to be handicraftsmen,
beyond the age of thirteen or fourteen is neither practicable nor
desirable; and, as it is quite certain, that, with justice to other
and no less important branches of education, nothing more than the
rudiments of science and art teaching can be introduced into elementary
schools, we must seek elsewhere for a supplementary training in these
subjects, and, if need be, in foreign languages, which may go on after
the workman’s life has begun.

The means of acquiring the scientific and artistic part of this
training already exists in full working order, in the first place, in
the classes of the Science and Art Department, which are, for the most
part, held in the evening, so as to be accessible to all who choose to
avail themselves of them after working hours. The great advantage of
these classes is that they bring the means of instruction to the doors
of the factories and workshops; that they are no artificial creations,
but by their very existence prove the desire of the people for them;
and finally, that they admit of indefinite development in proportion
as they are wanted. I have often expressed the opinion, and I repeat
it here, that, during the eighteen years they have been in existence,
these classes have done incalculable good; and I can say, of my own
knowledge, that the Department spares no pains and trouble in trying to
increase their usefulness and ensure the soundness of their work.

No one knows better than my friend Colonel Donnelly, to whose clear
views and great administrative abilities so much of the successful
working of the science classes is due, that there is much to be done
before the system can be said to be thoroughly satisfactory. The
instruction given needs to be made more systematic and especially more
practical; the teachers are of very unequal excellence, and not a few
stand much in need of instruction themselves, not only in the subjects
which they teach, but in the objects for which they teach. I daresay
you have heard of that proceeding, reprobated by all true sportsmen,
which is called “shooting for the pot.” Well, there is such a thing
as “teaching for the pot”—teaching, that is, not that your scholar
may know, but that he may count for payment among those who pass the
examination; and there are some teachers, happily not many, who have
yet to learn that the examiners of the Department regard them as
poachers of the worst description.

Without presuming in any way to speak in the name of the Department, I
think I may say, as a matter which has come under my own observation,
that it is doing its best to meet all these difficulties. It
systematically promotes practical instruction in the classes; it
affords facilities to teachers who desire to learn their business
thoroughly; and it is always ready to aid in the suppression of
pot-teaching.

All this is, as you may imagine, highly satisfactory to me. I see that
spread of scientific education, about which I have so often permitted
myself to worry the public, become, for all practical purposes, an
accomplished fact. Grateful as I am for all that is now being done,
in the same direction, in our higher schools and universities, I have
ceased to have any anxiety about the wealthier classes. Scientific
knowledge is spreading by what the alchemists called a “distillatio per
ascensum;” and nothing now can prevent it from continuing to distil
upwards and permeate English society, until, in the remote future,
there shall be no member of the legislature who does not know as much
of science as an elementary school-boy; and even the heads of houses
in our venerable seats of learning shall acknowledge that natural
science is not merely a sort of University back-door through which
inferior men may get at their degrees. Perhaps this apocalyptic vision
is a little wild; and I feel I ought to ask pardon for an outbreak of
enthusiasm, which, I assure you, is not my commonest failing. I have
said that the Government is already doing a great deal in aid of that
kind of technical education for handicraftsmen which, to my mind, is
alone worth seeking. Perhaps it is doing as much as it ought to do,
even in this direction. Certainly there is another kind of help of the
most important character, for which we may look elsewhere than to the
Government. The great mass of mankind have neither the liking, nor the
aptitude, for either literary, or scientific, or artistic pursuits;
nor, indeed, for excellence of any sort. Their ambition is to go
through life with moderate exertion and a fair share of ease, doing
common things in a common way. And a great blessing and comfort it is
that the majority of men are of this mind; for the majority of things
to be done are common things, and are quite well enough done when
commonly done. The great end of life is not knowledge but action. What
men need is, as much knowledge as they can assimilate and organise into
a basis for action; give them more and it may become injurious. One
knows people who are as heavy and stupid from undigested learning as
others are from over-fulness of meat and drink. But a small percentage
of the population is born with that most excellent quality, a desire
for excellence, or with special aptitudes of some sort or another; Mr.
Galton tells us that not more than one in four thousand may be expected
to attain distinction, and not more than one in a million some share
of that intensity of instinctive aptitude, that burning thirst for
excellence, which is called genius.

Now, the most important object of all educational schemes is to
catch these exceptional people, and turn them to account for the
good of society. No man can say where they will crop up; like their
opposites, the fools and knaves, they appear sometimes in the palace,
and sometimes in the hovel; but the great thing to be aimed at, I was
almost going to say the most important end of all social arrangements,
is to keep these glorious sports of Nature from being either corrupted
by luxury or starved by poverty, and to put them into the position in
which they can do the work for which they are specially fitted.

Thus, if a lad in an elementary school showed signs of special
capacity, I would try to provide him with the means of continuing his
education after his daily working life had begun; if, in the evening
classes, he developed special capabilities in the direction of science
or of drawing, I would try to secure him an apprenticeship to some
trade in which those powers would have applicability. Or, if he chose
to become a teacher, he should have the chance of so doing. Finally, to
the lad of genius, the one in a million, I would make accessible the
highest and most complete training the country could afford. Whatever
that might cost, depend upon it the investment would be a good one. I
weigh my words when I say that if the nation could purchase a potential
Watt, or Davy, or Faraday, at the cost of a hundred thousand pounds
down, he would be dirt-cheap at the money. It is a mere commonplace
and everyday piece of knowledge, that what these three men did has
produced untold millions of wealth, in the narrowest economical sense
of the word.

Therefore, as the sum and crown of what is to be done for technical
education, I look to the provision of a machinery for winnowing out the
capacities and giving them scope. When I was a member of the London
School Board, I said, in the course of a speech, that our business
was to provide a ladder, reaching from the gutter to the university,
along which every child in the three kingdoms should have the chance of
climbing as far as he was fit to go. This phrase was so much bandied
about at the time, that, to say truth, I am rather tired of it; but I
know of no other which so fully expresses my belief, not only about
education in general, but about technical education in particular.

The essential foundation of all the organisation needed for the
promotion of education among handicraftsmen will, I believe, exist in
this country, when every working lad can feel that society has done
as much as lies in its power to remove all needless and artificial
obstacles from his path; that there is no barrier, except such as
exists in the nature of things, between himself and whatever place in
the social organisation he is fitted to fill; and, more than this,
that, if he has capacity and industry, a hand is held out to help him
along any path which is wisely and honestly chosen.

I have endeavoured to point out to you that a great deal of such an
organisation already exists; and I am glad to be able to add that
there is a good prospect that what is wanting will, before long, be
supplemented.

Those powerful and wealthy societies, the livery companies of the City
of London, remembering that they are the heirs and representatives of
the trade guilds of the Middle Ages, are interesting themselves in the
question. So far back as 1872 the Society of Arts organised a system
of instruction in the technology of arts and manufactures, for persons
actually employed in factories and workshops, who desired to extend and
improve their knowledge of the theory and practice of their particular
avocations;[8] and a considerable subsidy, in aid of the efforts of
the Society, was liberally granted by the Clothworkers’ Company. We
have here the hopeful commencement of a rational organisation for the
promotion of excellence among handicraftsmen. Quite recently, other of
the livery companies have determined upon giving their powerful, and,
indeed, almost boundless, aid to the improvement of the teaching of
handicrafts. They have already gone so far as to appoint a committee
to act for them; and I betray no confidence in adding that, some time
since, the committee sought the advice and assistance of several
persons, myself among the number.

Of course I cannot tell you what may be the result of the deliberations
of the committee; but we may all fairly hope that, before long, steps
which will have a weighty and a lasting influence on the growth and
spread of sound and thorough teaching among the handicraftsmen[9] of
this country will be taken by the livery companies of London.

  [This hope has been fully justified by the establishment
  of the Cowper Street Schools, and that of the Central
  Institution of the City and Guilds of London Institute.
  September 1881.]




IV.

ON ELEMENTARY INSTRUCTION IN PHYSIOLOGY.


The chief ground upon which I venture to recommend that the teaching of
elementary physiology should form an essential part of any organised
course of instruction in matters pertaining to domestic economy, is,
that a knowledge of even the elements of this subject supplies those
conceptions of the constitution and mode of action of the living body,
and of the nature of health and disease, which prepare the mind to
receive instruction from sanitary science.

It is, I think, eminently desirable that the hygienist and the
physician should find something in the public mind to which they can
appeal; some little stock of universally acknowledged truths, which may
serve as a foundation for their warnings, and predispose towards an
intelligent obedience to their recommendations.

Listening to ordinary talk about health, disease, and death, one is
often led to entertain a doubt whether the speakers believe that the
course of natural causation runs as smoothly in the human body as
elsewhere. Indications are too often obvious of a strong, though
perhaps an unavowed and half unconscious, under-current of opinion
that the phenomena of life are not only widely different, in their
superficial characters and in their practical importance, from other
natural events, but that they do not follow in that definite order
which characterises the succession of all other occurrences, and the
statement of which we call a law of nature.

Hence, I think, arises the want of heartiness of belief in the value
of knowledge respecting the laws of health and disease, and of the
foresight and care to which knowledge is the essential preliminary,
which is so often noticeable; and a corresponding laxity and
carelessness in practice, the results of which are too frequently
lamentable.

It is said that among the many religious sects of Russia, there is one
which holds that all disease is brought about by the direct and special
interference of the Deity, and which, therefore, looks with repugnance
upon both preventive and curative measures as alike blasphemous
interferences with the will of God. Among ourselves, the “Peculiar
People” are, I believe, the only persons who hold the like doctrine
in its integrity, and carry it out with logical rigour. But many of
us are old enough to recollect that the administration of chloroform
in assuagement of the pangs of childbirth was, at its introduction,
strenuously resisted upon similar grounds.

I am not sure that the feeling, of which the doctrine to which I have
referred is the full expression, does not lie at the bottom of the
minds of a great many people who yet would vigorously object to give
a verbal assent to the doctrine itself. However this may be, the main
point is that sufficient knowledge has now been acquired of vital
phenomena, to justify the assertion, that the notion, that there is
anything exceptional about these phenomena, receives not a particle of
support from any known fact. On the contrary, there is a vast and an
increasing mass of evidence that birth and death, health and disease,
are as much parts of the ordinary stream of events as the rising and
setting of the sun, or the changes of the moon; and that the living
body is a mechanism, the proper working of which we term health;
its disturbance, disease; its stoppage, death. The activity of this
mechanism is dependent upon many and complicated conditions, some of
which are hopelessly beyond our control, while others are readily
accessible, and are capable of being indefinitely modified by our own
actions. The business of the hygienist and of the physician is to know
the range of these modifiable conditions, and how to influence them
towards the maintenance of health and the prolongation of life; the
business of the general public is to give an intelligent assent, and
a ready obedience based upon that assent, to the rules laid down for
their guidance by such experts. But an intelligent assent is an assent
based upon knowledge, and the knowledge which is here in question means
an acquaintance with the elements of physiology.

It is not difficult to acquire such knowledge. What is true, to
a certain extent, of all the physical sciences, is eminently
characteristic of physiology—the difficulty of the subject begins
beyond the stage of elementary knowledge, and increases with every
stage of progress. While the most highly trained and the best furnished
intellect may find all its resources insufficient, when it strives to
reach the heights and penetrate into the depths of the problems of
physiology, the elementary and fundamental truths can be made clear to
a child.

No one can have any difficulty in comprehending the mechanism of
circulation or respiration; or the general mode of operation of the
organ of vision; though the unravelling of all the minutiæ of these
processes, may, for the present, baffle the conjoined attacks of
the most accomplished physicists, chemists, and mathematicians. To
know the anatomy of the human body, with even an approximation to
thoroughness, is the work of a life; but as much as is needed for a
sound comprehension of elementary physiological truths, may be learned
in a week.

A knowledge of the elements of physiology is not only easy of
acquirement, but it may be made a real and practical acquaintance
with the facts, as far as it goes. The subject of study is always at
hand, in oneself. The principal constituents of the skeleton, and the
changes of form of contracting muscles, may be felt through one’s
own skin. The beating of one’s heart, and its connection with the
pulse, may be noted; the influence of the valves of one’s own veins
may be shown; the movements of respiration may be observed; while the
wonderful phenomena of sensation afford an endless field for curious
and interesting self-study. The prick of a needle will yield, in a drop
of one’s own blood, material for microscopic observation of phenomena
which lie at the foundation of all biological conceptions; and a cold,
with its concomitant coughing and sneezing, may prove the sweet uses
of adversity by helping one to a clear conception of what is meant by
“reflex action.”

Of course there is a limit to this physiological self-examination.
But there is so close a solidarity between ourselves and our poor
relations of the animal world, that our inaccessible inward parts
may be supplemented by theirs. A comparative anatomist knows that a
sheep’s heart and lungs, or eye, must not be confounded with those of
a man; but, so far as the comprehension of the elementary facts of the
physiology of circulation, of respiration, and of vision goes, the one
furnishes the needful anatomical data as well as the other.

Thus, it is quite possible to give instruction in elementary physiology
in such a manner as, not only to confer knowledge, which, for the
reason I have mentioned, is useful in itself; but to serve the purposes
of a training in accurate observation, and in the methods of reasoning
of physical science. But that is an advantage which I mention only
incidentally, as the present Conference does not deal with education in
the ordinary sense of the word.

It will not be suspected that I wish to make physiologists of all the
world. It would be as reasonable to accuse an advocate of the “three
R’s” of a desire to make an orator, an author, and a mathematician of
everybody. A stumbling reader, a pot-hook writer, and an arithmetician
who has not got beyond the rule of three, is not a person of brilliant
acquirements; but the difference between such a member of society and
one who can neither read, write, nor cipher is almost inexpressible;
and no one now-a-days doubts the value of instruction, even if it goes
no farther.

The saying that a little knowledge is a dangerous thing is, to my
mind, a very dangerous adage. If knowledge is real and genuine, I do
not believe that it is other than a very valuable possession, however
infinitesimal its quantity may be. Indeed, if a little knowledge is
dangerous, where is the man who has so much as to be out of danger?

If William Harvey’s life-long labours had revealed to him a tenth
part of that which may be made sound and real knowledge to our boys
and girls, he would not only have been what he was, the greatest
physiologist of his age, but he would have loomed upon the seventeenth
century as a sort of intellectual portent. Our “little knowledge” would
have been to him a great, astounding, unlooked-for vision of scientific
truth.

I really see no harm which can come of giving our children a little
knowledge of physiology. But then, as I have said, the instruction
must be real, based upon observation, eked out by good explanatory
diagrams and models, and conveyed by a teacher whose own knowledge has
been acquired by a study of the facts; and not the mere catechismal
parrot-work which too often usurps the place of elementary teaching.

It is, I hope, unnecessary for me to give a formal contradiction to
the silly fiction, which is assiduously circulated by fanatics who not
only ought to know, but do know, that their assertions are untrue,
that I have advocated the introduction of that experimental discipline
which is absolutely indispensable to the professed physiologist, into
elementary teaching.

But while I should object to any experimentation which can justly be
called painful, for the purpose of elementary instruction; and, while,
as a member of a late Royal Commission, I gladly did my best to prevent
the infliction of needless pain, for any purpose; I think it is my duty
to take this opportunity of expressing my regret at a condition of the
law which permits a boy to troll for pike, or set lines with live frog
bait, for idle amusement; and, at the same time, lays the teacher of
that boy open to the penalty of fine and imprisonment, if he uses the
same animal for the purpose of exhibiting one of the most beautiful
and instructive of physiological spectacles, the circulation in the
web of the foot. No one could undertake to affirm that a frog is not
inconvenienced by being wrapped up in a wet rag, and having his toes
tied out; and it cannot be denied that inconvenience is a sort of pain.
But you must not inflict the least pain on a vertebrated animal for
scientific purposes (though you may do a good deal in that way for gain
or for sport) without due licence of the Secretary of State for the
Home Department, granted under the authority of the Vivisection Act.

So it comes about, that, in this present year of grace 1877, two
persons may be charged with cruelty to animals. One has impaled a frog,
and suffered the creature to writhe about in that condition for hours;
the other has pained the animal no more than one of us would be pained
by tying strings round his fingers, and keeping him in the position
of a hydropathic patient. The first offender says, “I did it because
I find fishing very amusing,” and the magistrate bids him depart in
peace; nay, probably wishes him good sport. The second pleads, “I
wanted to impress a scientific truth, with a distinctness attainable in
no other way, on the minds of my scholars,” and the magistrate fines
him five pounds.

I cannot but think that this is an anomalous and not wholly creditable
state of things.




V.

JOSEPH PRIESTLEY.


If the man to perpetuate whose memory we have this day raised a
statue had been asked on what part of his busy life’s work he set the
highest value, he would undoubtedly have pointed to his voluminous
contributions to theology. In season and out of season, he was the
steadfast champion of that hypothesis respecting the Divine nature
which is termed Unitarianism by its friends and Socinianism by its
foes. Regardless of odds, he was ready to do battle with all comers in
that cause; and if no adversaries entered the lists, he would sally
forth to seek them.

To this, his highest ideal of duty, Joseph Priestley sacrificed the
vulgar prizes of life, which, assuredly, were within easy reach of a
man of his singular energy and varied abilities. For this object, he
put aside, as of secondary importance, those scientific investigations
which he loved so well, and in which he showed himself so competent
to enlarge the boundaries of natural knowledge and to win fame. In
this cause, he not only cheerfully suffered obloquy from the bigoted
and the unthinking, and came within sight of martyrdom; but bore with
that which is much harder to be borne than all these, the unfeigned
astonishment and hardly disguised contempt of a brilliant society,
composed of men whose sympathy and esteem must have been most dear to
him, and to whom it was simply incomprehensible that a philosopher
should seriously occupy himself with any form of Christianity.

It appears to me that the man who, setting before himself such an ideal
of life, acted up to it consistently, is worthy of the deepest respect,
whatever opinion may be entertained as to the real value of the tenets
which he so zealously propagated and defended.

But I am sure that I speak not only for myself, but for all this
assemblage, when I say that our purpose to-day is to do honour, not
to Priestley, the Unitarian divine, but to Priestley, the fearless
defender of rational freedom in thought and in action: to Priestley,
the philosophic thinker; to that Priestley who held a foremost place
among “the swift runners who hand over the lamp of life,”[10] and
transmit from one generation to another the fire kindled, in the
childhood of the world, at the Promethean altar of Science.


The main incidents of Priestley’s life are so well known that I need
dwell upon them at no great length.

Born in 1733, at Fieldhead, near Leeds, and brought up among Calvinists
of the straitest orthodoxy, the boy’s striking natural ability led to
his being devoted to the profession of a minister of religion; and, in
1752, he was sent to the Dissenting Academy at Daventry—an institution
which authority left undisturbed, though its existence contravened the
law. The teachers under whose instruction and influence the young man
came at Daventry, carried out to the letter the injunction to “try all
things: hold fast that which is good,” and encouraged the discussion
of every imaginable proposition with complete freedom, the leading
professors taking opposite sides; a discipline which, admirable as
it may be from a purely scientific point of view, would seem to be
calculated to make acute, rather than sound, divines. Priestley tells
us, in his “Autobiography,” that he generally found himself on the
unorthodox side: and, as he grew older, and his faculties attained
their maturity, this native tendency towards heterodoxy grew with his
growth and strengthened with his strength. He passed from Calvinism to
Arianism; and finally, in middle life, landed in that very broad form
of Unitarianism, by which his craving after a credible and consistent
theory of things was satisfied.

On leaving Daventry, Priestley became minister of a congregation, first
at Needham Market, and secondly at Nantwich; but whether on account
of his heterodox opinions, or of the stuttering which impeded his
expression of them in the pulpit, little success attended his efforts
in this capacity. In 1761, a career much more suited to his abilities
became open to him. He was appointed “tutor in the languages” in the
Dissenting Academy at Warrington, in which capacity, besides giving
three courses of lectures, he taught Latin, Greek, French, and Italian,
and read lectures on the Theory of Language and Universal Grammar, on
Oratory, Philosophical Criticism, and Civil law. And it is interesting
to observe that, as a teacher, he encouraged and cherished in those
whom he instructed, the freedom which he had enjoyed, in his own
student days, at Daventry. One of his pupils tells us that,

  “At the conclusion of his lecture, he always encouraged
  his students to express their sentiments relative to the
  subject of it, and to urge any objections to what he had
  delivered, without reserve. It pleased him when any one
  commenced such a conversation. In order to excite the
  freest discussion, he occasionally invited the students
  to drink tea with him, in order to canvass the subjects
  of his lectures. I do not recollect that he ever showed
  the least displeasure at the strongest objections that
  were made to what he delivered, but I distinctly remember
  the smile of approbation with which he usually received
  them: nor did he fail to point out, in a very encouraging
  manner, the ingenuity or force of any remarks that were
  made, when they merited these characters. His object,
  as well as Dr. Aikin’s, was to engage the students to
  examine and decide for themselves, uninfluenced by the
  sentiments of any other persons.”[11]

It would be difficult to give a better description of a model teacher
than that conveyed in these words.

From his earliest days, Priestley had shown a strong bent towards the
study of nature; and his brother Timothy tells us that the boy put
spiders into bottles, to see how long they would live in the same air—a
curious anticipation of the investigations of his later years. At
Nantwich, where he set up a school, Priestley informs us that he bought
an air pump, an electrical machine, and other instruments, in the use
of which he instructed his scholars. But he does not seem to have
devoted himself seriously to physical science until 1766, when he had
the great good fortune to meet Benjamin Franklin, whose friendship he
ever afterwards enjoyed. Encouraged by Franklin, he wrote a “History of
Electricity,” which was published in 1767, and appears to have met with
considerable success.

In the same year, Priestley left Warrington to become the minister of
a congregation at Leeds; and, here, happening to live next door to a
public brewery, as he says,

  “I, at first, amused myself with making experiments on
  the fixed air which I found ready-made in the process
  of fermentation. When I removed from that house I was
  under the necessity of making fixed air for myself; and
  one experiment leading to another, as I have distinctly
  and faithfully noted in my various publications on the
  subject, I by degrees contrived a convenient apparatus
  for the purpose, but of the cheapest kind.

  “When I began these experiments I knew very little
  of _chemistry_, and had, in a manner, no idea on the
  subject before I attended a course of chemical lectures,
  delivered in the Academy at Warrington, by Dr. Turner of
  Liverpool. But I have often thought that, upon the whole,
  this circumstance was no disadvantage to me; as, in this
  situation, I was led to devise an apparatus and processes
  of my own, adapted to my peculiar views; whereas, if I
  had been previously accustomed to the usual chemical
  processes, I should not have so easily thought of any
  other, and without new modes of operation, I should
  hardly have discovered anything materially new.”[12]

The first outcome of Priestley’s chemical work, published in 1772, was
of a very practical character. He discovered the way of impregnating
water with an excess of “fixed air,” or carbonic acid, and thereby
producing what we now know as “soda water”—a service to naturally,
and still more to artificially, thirsty souls, which those whose
parched throats and hot heads are cooled by morning draughts of
that beverage, cannot too gratefully acknowledge. In the same year,
Priestley communicated the extensive series of observations which his
industry and ingenuity had accumulated, in the course of four years,
to the Royal Society, under the title of “Observations on Different
Kinds of Air”—a memoir which was justly regarded of so much merit and
importance, that the Society at once conferred upon the author the
highest distinction in their power, by awarding him the Copley Medal.

In 1771 a proposal was made to Priestley to accompany Captain Cook
in his second voyage to the South Seas. He accepted it, and his
congregation agreed to pay an assistant to supply his place during
his absence. But the appointment lay in the hands of the Board of
Longitude, of which certain clergymen were members; and whether these
worthy ecclesiastics feared that Priestley’s presence among the ship’s
company might expose his Majesty’s Sloop _Resolution_ to the fate which
aforetime befell a certain ship that went from Joppa to Tarshish; or
whether they were alarmed lest a Socinian should undermine that piety
which, in the days of Commodore Trunnion, so strikingly characterised
sailors, does not appear; but, at any rate, they objected to Priestley
“on account of his religious principles,” and appointed the two
Forsters, whose “religious principles,” if they had been known to these
well-meaning but not far-sighted persons, would probably have surprised
them.

In 1772 another proposal was made to Priestley. Lord Shelburne,
desiring a “literary companion,” had been brought into communication
with Priestley by the good offices of a friend of both, Dr. Price;
and offered him the nominal post of librarian, with a good house
and appointments, and an annuity in case of the termination of the
engagement. Priestley accepted the offer, and remained with Lord
Shelburne for seven years, sometimes residing at Calne, sometimes
travelling abroad with the Earl.

Why the connection terminated has never been exactly known; but it
is certain that Lord Shelburne behaved with the utmost consideration
and kindness towards Priestley; that he fulfilled his engagements to
the letter; and that, at a later period, he expressed a desire that
Priestley should return to his old footing in his house. Probably
enough, the politician, aspiring to the highest offices in the state,
may have found the position of the protector of a man who was being
denounced all over the country as an infidel and an atheist somewhat
embarrassing. In fact, a passage in Priestley’s “Autobiography” on the
occasion of the publication of his “Disquisitions relating to Matter
and Spirit,” which took place in 1777, indicates pretty clearly the
state of the case:—

  “(126) It being probable that this publication would be
  unpopular, and might be the means of bringing odium on
  my patron, several attempts were made by his friends,
  though none by himself, to dissuade me from persisting
  in it. But being, as I thought, engaged in the cause
  of important truth, I proceeded without regard to any
  consequences, assuring them that this publication should
  not be injurious to his lordship.”

It is not unreasonable to suppose that his lordship, as a keen,
practical man of the world, did not derive much satisfaction from this
assurance. The “evident marks of dissatisfaction” which Priestley says
he first perceived in his patron in 1778, may well have arisen from
the peer’s not unnatural uneasiness as to what his domesticated, but
not tamed, philosopher might write next, and what storm might thereby
be brought down on his own head; and it speaks very highly for Lord
Shelburne’s delicacy that, in the midst of such perplexities, he
made not the least attempt to interfere with Priestley’s freedom of
action. In 1780, however, he intimated to Dr. Price that he should be
glad to establish Priestley on his Irish estates: the suggestion was
interpreted, as Lord Shelburne probably intended it should be, and
Priestley left him, the annuity of £150 a year, which had been promised
in view of such a contingency, being punctually paid.

After leaving Calne, Priestley spent some little time in London, and
then, having settled in Birmingham at the desire of his brother-in-law,
he was soon invited to become the minister of a large congregation.
This settlement Priestley considered, at the time, to be “the happiest
event of his life.” And well he might think so; for it gave him
competence and leisure; placed him within reach of the best makers
of apparatus of the day; made him a member of that remarkable “Lunar
Society,” at whose meetings he could exchange thoughts with such men
as Watt, Wedgewood, Darwin, and Boulton; and threw open to him the
pleasant house of the Galtons of Barr, where these men, and others of
less note, formed a society of exceptional charm and intelligence.[13]

But these halcyon days were ended by a bitter storm. The French
Revolution broke out. An electric shock ran through the nations;
whatever there was of corrupt and retrograde, and, at the same time,
a great deal of what there was of best and noblest, in European
society shuddered at the outburst of long-pent-up social fires.
Men’s feelings were excited in a way that we, in this generation,
can hardly comprehend. Party wrath and virulence were expressed in
a manner unparalleled, and it is to be hoped impossible, in our
times; and Priestley and his friends were held up to public scorn,
even in Parliament, as fomenters of sedition. A “Church-and-King” cry
was raised against the Liberal Dissenters; and, in Birmingham, it
was intensified and specially directed towards Priestley by a local
controversy, in which he had engaged with his usual vigour. In 1791,
the celebration of the second anniversary of the taking of the Bastille
by a public dinner, with which Priestley had nothing whatever to do,
gave the signal to the loyal and pious mob, who, unchecked, and indeed
to some extent encouraged, by those who were responsible for order, had
the town at their mercy for three days. The chapels and houses of the
leading Dissenters were wrecked, and Priestley and his family had to
fly for their lives, leaving library, apparatus, papers, and all their
possessions, a prey to the flames.

Priestley never returned to Birmingham. He bore the outrages and losses
inflicted upon him with extreme patience and sweetness,[14] and betook
himself to London. But even his scientific colleagues gave him a cold
shoulder; and though he was elected minister of a congregation at
Hackney, he felt his position to be insecure, and finally determined on
emigrating to the United States. He landed in America in 1794; lived
quietly with his sons at Northumberland, in Pennsylvania, where his
posterity still flourish; and, clear-headed and busy to the last, died
on the 6th of February 1804.


Such were the conditions under which Joseph Priestley did the work
which lay before him, and then, as the Norse Sagas say, went out of the
story. The work itself was of the most varied kind. No human interest
was without its attraction for Priestley, and few men have ever had
so many irons in the fire at once; but, though he may have burned his
fingers a little, very few who have tried that operation have burned
their fingers so little. He made admirable discoveries in science; his
philosophical treatises are still well worth reading; his political
works are full of insight and replete with the spirit of freedom; and
while all these sparks flew off from his anvil, the controversial
hammer rained a hail of blows on orthodox priest and bishop. While
thus engaged, the kindly, cheerful doctor felt no more wrath or
uncharitableness towards his opponents than a smith does towards his
iron. But if the iron could only speak!—and the priests and bishops
took the point of view of the iron.

No doubt what Priestley’s friends repeatedly urged upon him—that he
would have escaped the heavier trials of his life and done more for the
advancement of knowledge, if he had confined himself to his scientific
pursuits and let his fellow-men go their way—was true. But it seems to
have been Priestley’s feeling that he was a man and a citizen before
he was a philosopher, and that the duties of the two former positions
are at least as imperative as those of the latter. Moreover, there are
men (and I think Priestley was one of them) to whom the satisfaction
of throwing down a triumphant fallacy is as great as that which
attends the discovery of a new truth; who feel better satisfied with
the government of the world, when they have been helping Providence
by knocking an imposture on the head; and who care even more for
freedom of thought than for mere advance of knowledge. These men are
the Carnots who organise victory for truth, and they are, at least, as
important as the generals who visibly fight her battles in the field.


Priestley’s reputation as a man of science rests upon his numerous and
important contributions to the chemistry of gaseous bodies; and to form
a just estimate of the value of his work—of the extent to which it
advanced the knowledge of fact and the development of sound theoretical
views—we must reflect what chemistry was in the first half of the
eighteenth century.

The vast science which now passes under that name had no existence.
Air, water, and fire were still counted among the elemental bodies;
and though Van Helmont, a century before, had distinguished different
kinds of air as _gas ventosum_ and _gas sylvestre_, and Boyle and
Hales had experimentally defined the physical properties of air, and
discriminated some of the various kinds of aëriform bodies, no one
suspected the existence of the numerous totally distinct gaseous
elements which are now known, or dreamed that the air we breathe and
the water we drink are compounds of gaseous elements.

But, in 1754, a young Scotch physician, Dr. Black, made the first
clearing in this tangled backwood of knowledge. And it gives one a
wonderful impression of the juvenility of scientific chemistry to think
that Lord Brougham, whom so many of us recollect, attended Black’s
lectures when he was a student in Edinburgh. Black’s researches gave
the world the novel and startling conception of a gas that was a
permanently elastic fluid like air, but that differed from common air
in being much heavier, very poisonous, and in having the properties of
an acid, capable of neutralising the strongest alkalies; and it took
the world some time to become accustomed to the notion.

A dozen years later, one of the most sagacious and accurate
investigators who has adorned this, or any other, country, Henry
Cavendish, published a memoir in the “Philosophical Transactions,” in
which he deals not only with the “fixed air” (now called carbonic acid
or carbonic anhydride) of Black, but with “inflammable air,” or what we
now term hydrogen.

By the rigorous application of weight and measure to all his processes,
Cavendish implied the belief subsequently formulated by Lavoisier,
that, in chemical processes, matter is neither created nor destroyed,
and indicated the path along which all future explorers must travel.
Nor did he himself halt until this path led him, in 1784, to the
brilliant and fundamental discovery that water is composed of two gases
united in fixed and constant proportions.

It is a trying ordeal for any man to be compared with Black and
Cavendish, and Priestley cannot be said to stand on their level.
Nevertheless, his achievements are not only great in themselves, but
truly wonderful, if we consider the disadvantages under which he
laboured. Without the careful scientific training of Black, without the
leisure and appliances secured by the wealth of Cavendish, he scaled
the walls of science as so many Englishmen have done before and since
his day; and trusting to mother wit to supply the place of training,
and to ingenuity to create apparatus out of washing tubs, he discovered
more new gases than all his predecessors put together had done. He
laid the foundations of gas analysis; he discovered the complementary
actions of animal and vegetable life upon the constituents of the
atmosphere; and, finally, he crowned his work, this day one hundred
years ago, by the discovery of that “pure dephlogisticated air” to
which the French chemists subsequently gave the name of oxygen. Its
importance, as the constituent of the atmosphere which disappears in
the processes of respiration and combustion, and is restored by green
plants growing in sunshine, was proved somewhat later. For these
brilliant discoveries, the Royal Society elected Priestley a fellow and
gave him their medal, while the Academies of Paris and St. Petersburg
conferred their membership upon him. Edinburgh had made him an
honorary doctor of laws at an early period of his career; but, I need
hardly add, that a man of Priestley’s opinions received no recognition
from the universities of his own country.

That Priestley’s contributions to the knowledge of chemical fact were
of the greatest importance, and that they richly deserve all the praise
that has been awarded to them, is unquestionable; but it must, at the
same time, be admitted that he had no comprehension of the deeper
significance of his work; and, so far from contributing anything to the
theory of the facts which he discovered, or assisting in their rational
explanation, his influence to the end of his life was warmly exerted
in favour of error. From first to last, he was a stiff adherent of the
phlogiston doctrine which was prevalent when his studies commenced;
and, by a curious irony of fate, the man who by the discovery of what
he called “dephlogisticated air” furnished the essential datum for the
true theory of combustion, of respiration, and of the composition of
water, to the end of his days fought against the inevitable corollaries
from his own labours. His last scientific work, published in 1800,
bears the title, “The Doctrine of Phlogiston established, and that of
the Composition of Water refuted.”

When Priestley commenced his studies, the current belief was, that
atmospheric air, freed from accidental impurities, is a simple
elementary substance, indestructible and unalterable, as water was
supposed to be. When a combustible burned, or when an animal breathed
in air, it was supposed that a substance, “phlogiston,” the matter of
heat and light, passed from the burning or breathing body into it,
and destroyed its powers of supporting life and combustion. Thus, air
contained in a vessel in which a lighted candle had gone out, or a
living animal had breathed until it could breathe no longer, was called
“phlogisticated.” The same result was supposed to be brought about by
the addition of what Priestley called “nitrous gas” to common air.

In the course of his researches, Priestley found that the quantity of
common air which can thus become “phlogisticated,” amounts to about
one-fifth the volume of the whole quantity submitted to experiment.
Hence it appeared that common air consists, to the extent of
four-fifths of its volume, of air which is already “phlogisticated;”
while the other fifth is free from phlogiston, or “dephlogisticated.”
On the other hand, Priestley found that air “phlogisticated” by
combustion or respiration could be “dephlogisticated,” or have the
properties of pure common air restored to it, by the action of green
plants in sunshine. The question, therefore, would naturally arise—as
common air can be wholly phlogisticated by combustion, and converted
into a substance which will no longer support combustion, is it
possible to get air that shall be less phlogisticated than common air,
and consequently support combustion better than common air does?

Now, Priestley says that, in 1774, the possibility of obtaining air
less phlogisticated than common air had not occurred to him.[15] But
in pursuing his experiments on the evolution of air from various bodies
by means of heat, it happened that, on the 1st of August 1774, he threw
the heat of the sun, by means of a large burning glass which he had
recently obtained, upon a substance which was then called _mercurius
calcinatus per se_, and which is commonly known as red precipitate.

  “I presently found that, by means of this lens, air was
  expelled from it very readily. Having got about three
  or four times as much as the bulk of my materials, I
  admitted water to it, and found that it was not imbibed
  by it. But what surprised me more than I can well
  express, was that a candle burned in this air with a
  remarkably vigorous flame, very much like that enlarged
  flame with which a candle burns in nitrous air, exposed
  to iron or lime of sulphur; but as I had got nothing like
  this remarkable appearance from any kind of air besides
  this particular modification of nitrous air, and I knew
  no nitrous acid was used in the preparation of _mercurius
  calcinatus_, I was utterly at a loss how to account for
  it.

  “In this case also, though I did not give sufficient
  attention to the circumstance at that time, the flame
  of the candle, besides being larger, burned with more
  splendour and heat than in that species of nitrous air;
  and a piece of red-hot wood sparkled in it, exactly like
  paper dipped in a solution of nitre, and it consumed very
  fast—an experiment which I had never thought of trying
  with nitrous air.”[16]

Priestley obtained the same sort of air from red lead, but, as he says
himself, he remained in ignorance of the properties of this new kind of
air for seven months, or until March 1775, when he found that the new
air behaved with “nitrous gas” in the same way as the dephlogisticated
part of common air does;[17] but that, instead of being diminished to
four-fifths, it almost completely vanished, and, therefore, showed
itself to be “between five and six times as good as the best common
air I have ever met with.”[18] As this new air thus appeared to be
completely free from phlogiston, Priestley called it “dephlogisticated
air.”

What was the nature of this air? Priestley found that the same kind of
air was to be obtained by moistening with the spirit of nitre (which he
terms nitrous acid) any kind of earth that is free from phlogiston, and
applying heat; and consequently he says: “There remained no doubt on
my mind but that the atmospherical air, or the thing that we breathe,
consists of the nitrous acid and earth, with so much phlogiston as is
necessary to its elasticity, and likewise so much more as is required
to bring it from its state of perfect purity to the mean condition in
which we find it.”[19]


Priestley’s view, in fact, is that atmospheric air is a kind of
saltpetre, in which the potash is replaced by some unknown earth.
And in speculating on the manner in which saltpetre is formed,
he enunciates the hypothesis, “that nitre is formed by a real
_decomposition of the air itself_, the _bases_ that are presented to
it having, in such circumstances, a nearer affinity with the spirit
of nitre than that kind of earth with which it is united in the
atmosphere.”[20]

It would have been hard for the most ingenious person to have wandered
farther from the truth than Priestley does in this hypothesis; and,
though Lavoisier undoubtedly treated Priestley very ill, and pretended
to have discovered dephlogisticated air, or oxygen, as he called it,
independently, we can almost forgive him, when we reflect how different
were the ideas which the great French chemist attached to the body
which Priestley discovered.

They are like two navigators of whom the first sees a new country, but
takes clouds for mountains and mirage for lowlands; while the second
determines its length and breadth, and lays down on a chart its exact
place, so that, thenceforth, it serves as a guide to his successors,
and becomes a secure outpost whence new explorations may be pushed.

Nevertheless, as Priestley himself somewhere remarks, the first object
of physical science is to ascertain facts, and the service which he
rendered to chemistry by the definite establishment of a large number
of new and fundamentally important facts, is such as to entitle him to
a very high place among the fathers of chemical science.


It is difficult to say whether Priestley’s philosophical, political, or
theological views were most responsible for the bitter hatred which was
borne to him by a large body of his countrymen,[21] and which found
its expression in the malignant insinuations in which Burke, to his
everlasting shame, indulged in the House of Commons.

Without containing much that will be new to the readers of Hobbes,
Spinoza, Collins, Hume, and Hartley, and, indeed, while making no
pretensions to originality, Priestley’s “Disquisitions relating to
Matter and Spirit,” and his “Doctrine of Philosophical Necessity
illustrated,” are among the most powerful, clear, and unflinching
expositions of materialism and necessarianism which exist in the
English language, and are still well worth reading.

Priestley denied the freedom of the will in the sense of its
self-determination; he denied the existence of a soul distinct from the
body; and as a natural consequence, he denied the natural immortality
of man.

In relation to these matters English opinion, a century ago, was very
much what it is now.

A man may be a necessarian without incurring graver reproach than that
implied in being called a gloomy fanatic, necessarianism, though very
shocking, having a note of Calvinistic orthodoxy; but, if a man is a
materialist; or, if good authorities say he is and must be so, in spite
of his assertion to the contrary; or, if he acknowledge himself unable
to see good reasons for believing in the natural immortality of man,
respectable folks look upon him as an unsafe neighbour of a cash-box,
as an actual or potential sensualist, the more virtuous in outward
seeming, the more certainly loaded with secret “grave personal sins.”

Nevertheless, it is as certain as anything can be, that Joseph
Priestley was no gloomy fanatic, but as cheerful and kindly a soul as
ever breathed, the idol of children; a man who was hated only by those
who did not know him, and who charmed away the bitterest prejudices
in personal intercourse; a man who never lost a friend, and the best
testimony to whose worth is the generous and tender warmth with which
his many friends vied with one another in rendering him substantial
help, in all the crises of his career.

The unspotted purity of Priestley’s life, the strictness of
his performance of every duty, his transparent sincerity, the
unostentatious and deep-seated piety which breathes through all his
correspondence, are in themselves a sufficient refutation of the
hypothesis, invented by bigots to cover uncharitableness, that such
opinions as his must arise from moral defects. And his statue will do
as good service as the brazen image that was set upon a pole before
the Israelites, if those who have been bitten by the fiery serpents of
sectarian hatred, which still haunt this wilderness of a world, are
made whole by looking upon the image of a heretic, who was yet a saint.

Though Priestley did not believe in the natural immortality of man, he
held with an almost naïve realism, that man would be raised from the
dead by a direct exertion of the power of God, and thenceforward be
immortal. And it may be as well for those who may be shocked by this
doctrine to know that views, substantially identical with Priestley’s,
have been advocated, since his time, by two prelates of the Anglican
Church: by Dr. Whately, Archbishop of Dublin, in his well-known
“Essays;”[22] and by Dr. Courtenay, Bishop of Kingston in Jamaica,
the first edition of whose remarkable book “On the Future States,”
dedicated to Archbishop Whately, was published in 1843 and the second
in 1857. According to Bishop Courtenay,

  “The death of the body will cause a cessation of all the
  activity of the mind by way of natural consequence; to
  continue for ever UNLESS the Creator should interfere.”

And again:—

  “The natural end of human existence is the ‘first death,’
  the dreamless slumber of the grave, wherein man lies
  spellbound, soul and body, under the dominion of sin
  and death—that whatever modes of conscious existence,
  whatever future states of ‘life’ or of ‘torment’ beyond
  Hades are reserved for man, are results of our blessed
  Lord’s victory over sin and death; that the resurrection
  of the dead must be preliminary to their entrance into
  either of the future states, and that the nature and even
  existence of these states and even the mere fact that
  there is a futurity of consciousness, can be known _only_
  through God’s revelation of Himself in the Person and the
  Gospel of His Son.”—P. 389.

And now hear Priestley:—

  “Man, according to this system (of materialism), is no
  more than we now see of him. His being commences at
  the time of his conception, or perhaps at an earlier
  period. The corporeal and mental faculties, in being in
  the same substance, grow, ripen, and decay together;
  and whenever the system is dissolved it continues in a
  state of dissolution till it shall please that Almighty
  Being who called it into existence to restore it to life
  again.”—“Matter and Spirit,” p. 49.

And again:—

  “The doctrine of the Scripture is, that God made man of
  the dust of the ground, and by simply animating this
  organised matter, made man that living percipient and
  intelligent being that he is. According to Revelation,
  _death_ is a state of rest and insensibility, and our
  only though sure hope of a future life is founded on
  the doctrine of the resurrection of the whole man at
  some distant period; this assurance being sufficiently
  confirmed to us both by the evident tokens of a Divine
  commission attending the persons who delivered the
  doctrine, and especially by the actual resurrection of
  Jesus Christ, which is more authentically attested than
  any other fact in history.”—_Ibid._, p. 247.

We all know that “a saint in crape is twice a saint in lawn;” but
it is not yet admitted that the views which are consistent with
such saintliness in lawn, become diabolical when held by a mere
dissenter.[23]

I am not here either to defend or to attack Priestley’s philosophical
views, and I cannot say that I am personally disposed to attach much
value to episcopal authority in philosophical questions; but it seems
right to call attention to the fact, that those of Priestley’s opinions
which have brought most odium upon him, have been openly promulgated,
without challenge, by persons occupying the highest positions in the
State Church.

I must confess that what interests me most about Priestley’s
materialism, is the evidence that he saw dimly the seed of destruction
which such materialism carries within its own bosom. In the course
of his reading for his “History of Discoveries relating to Vision,
Light, and Colours,” he had come upon the speculations of Boscovich
and Michell, and had been led to admit the sufficiently obvious truth
that our knowledge of matter is a knowledge of its properties; and that
of its substance—if it have a substance—we know nothing. And this led
to the further admission that, so far as we can know, there may be no
difference between the substance of matter and the substance of spirit
(“Disquisitions,” p. 16). A step farther would have shown Priestley
that his materialism was, essentially, very little different from the
Idealism of his contemporary, the Bishop of Cloyne.


As Priestley’s philosophy is mainly a clear statement of the views of
the deeper thinkers of his day, so are his political conceptions based
upon those of Locke. Locke’s aphorism that “the end of government is
the good of mankind,” is thus expanded by Priestley:—

  “It must necessarily be understood, therefore, whether it
  be expressed or not, that all people live in society for
  their mutual advantage; so that the good and happiness
  of the members, that is, of the majority of the members,
  of any state, is the great standard by which everything
  relating to that state must finally be determined.”[24]

The little sentence here interpolated, “that is, of the majority of
the members of any state,” appears to be that passage which suggested
to Bentham, according to his own acknowledgment, the famous “greatest
happiness” formula, which by substituting “happiness” for “good,” has
converted a noble into an ignoble principle. But I do not call to
mind that there is any utterance in Locke quite so outspoken as the
following passage in the “Essay on the First Principles of Government.”
After laying down as “a fundamental maxim in all governments,” the
proposition that “kings, senators, and nobles” are “the servants of the
public,” Priestley goes on to say:—

  “But in the largest states, if the abuses of the
  government should at any time be great and manifest; if
  the servants of the people, forgetting their masters and
  their masters’ interest, should pursue a separate one
  of their own; if, instead of considering that they are
  made for the people, they should consider the people as
  made for them; if the oppressions and violation of right
  should be great, flagrant, and universally resented; if
  the tyrannical governors should have no friends but a few
  sycophants, who had long preyed upon the vitals of their
  fellow-citizens, and who might be expected to desert a
  government whenever their interests should be detached
  from it; if, in consequence of these circumstances, it
  should become manifest that the risk which would be
  run in attempting a revolution would be trifling, and
  the evils which might be apprehended from it were far
  less than those which were actually suffered and which
  were daily increasing; in the name of God, I ask, what
  principles are those which ought to restrain an injured
  and insulted people from asserting their natural rights,
  and from changing or even punishing their governors—that
  is, their servants—who had abused their trust, or from
  altering the whole form of their government, if it
  appeared to be of a structure so liable to abuse?”

As a Dissenter, subject to the operation of the Corporation and Test
Acts, and as a Unitarian, excluded from the benefit of the Toleration
Act, it is not surprising to find that Priestley had very definite
opinions about Ecclesiastical Establishments; the only wonder is that
these opinions were so moderate as the following passages show them to
have been:—

  “Ecclesiastical authority may have been necessary in the
  infant state of society, and, for the same reason, it
  may perhaps continue to be, in some degree, necessary as
  long as society is imperfect; and therefore may not be
  entirely abolished till civil governments have arrived
  at a much greater degree of perfection. If, therefore,
  I were asked whether I should approve of the immediate
  dissolution of all the ecclesiastical establishments in
  Europe, I should answer, No.... Let experiment be first
  made of _alterations_, or, which is the same thing, of
  _better establishments_ than the present. Let them be
  reformed in many essential articles, and then not thrown
  aside entirely till it be found by experience that no
  good can be made of them.”

Priestley goes on to suggest four such reforms of a capital nature:—

  “1. Let the Articles of Faith to be subscribed by
  candidates for the ministry be greatly reduced. In
  the formulary of the Church of England, might not
  thirty-eight out of the thirty-nine be very well spared?
  It is a reproach to any Christian establishment if every
  man cannot claim the benefit of it who can say that he
  believes in the religion of Jesus Christ as it is set
  forth in the New Testament. You say the terms are so
  general that even Deists would quibble and insinuate
  themselves. I answer that all the articles which are
  subscribed at present, by no means exclude Deists who
  will prevaricate; and upon this scheme you would at least
  exclude fewer honest men.”[25]

The second reform suggested is the equalisation, in proportion to work
done, of the stipends of the clergy; the third, the exclusion of the
bishops from Parliament; and the fourth, complete toleration, so that
every man may enjoy the rights of a citizen, and be qualified to serve
his country, whether he belong to the Established Church or not.

Opinions such as those I have quoted, respecting the duties and
the responsibilities of governors, are the commonplaces of modern
Liberalism; and Priestley’s views on Ecclesiastical Establishments
would, I fear, meet with but a cool reception, as altogether too
conservative, from a large proportion of the lineal descendants of the
people who taught their children to cry “Damn Priestley;” and, with
that love for the practical application of science which is the source
of the greatness of Birmingham, tried to set fire to the doctor’s house
with sparks from his own electrical machine; thereby giving the man
they called an incendiary and raiser of sedition against Church and
King, an appropriately experimental illustration of the nature of arson
and riot.


If I have succeeded in putting before you the main features of
Priestley’s work, its value will become apparent, when we compare the
condition of the English nation, as he knew it, with its present state.

The fact that France has been for eighty-five years trying, without
much success, to right herself after the great storm of the Revolution,
is not unfrequently cited among us, as an indication of some inherent
incapacity for self-government among the French people. I think,
however, that Englishmen who argue thus, forget that, from the meeting
of the Long Parliament in 1640, to the last Stuart rebellion in 1745,
is a hundred and five years, and that, in the middle of the last
century, we had but just safely freed ourselves from our Bourbons and
all that they represented. The corruption of our state was as bad as
that of the Second Empire. Bribery was the instrument of government,
and peculation its reward. Four-fifths of the seats in the House of
Commons were more or less openly dealt with as property. A minister
had to consider the state of the vote market, and the sovereign secured
a sufficiency of “king’s friends” by payments allotted with retail,
rather than royal, sagacity.

Barefaced and brutal immorality and intemperance pervaded the land,
from the highest to the lowest classes of society. The Established
Church was torpid, so far as it was not a scandal; but those who
dissented from it came within the meshes of the Act of Uniformity, the
Test Act, and the Corporation Act. By law, such a man as Priestley,
being a Unitarian, could neither teach nor preach, and was liable to
ruinous fines and long imprisonment.[26] In those days, the guns that
were pointed by the Church against the Dissenters were shotted. The law
was a cesspool of iniquity and cruelty. Adam Smith was a new prophet
whom few regarded, and commerce was hampered by idiotic impediments,
and ruined by still more absurd help, on the part of government.

Birmingham, though already the centre of a considerable industry, was a
mere village as compared with its present extent. People who travelled
went about armed, by reason of the abundance of highwaymen and the
paucity and inefficiency of the police. Stage coaches had not reached
Birmingham, and it took three days to get to London. Even canals were a
recent and much opposed invention.

Newton had laid the foundation of a mechanical conception of the
physical universe: Hartley, putting a modern face upon ancient
materialism, had extended that mechanical conception to psychology;
Linnæus and Haller were beginning to introduce method and order into
the chaotic accumulation of biological facts. But those parts of
physical science which deal with heat, electricity, and magnetism,
and above all, chemistry, in the modern sense, can hardly be said
to have had an existence. No one knew that two of the old elemental
bodies, air and water, are compounds, and that a third, fire, is not a
substance but a motion. The great industries that have grown out of the
applications of modern scientific discoveries had no existence, and the
man who should have foretold their coming into being in the days of his
son, would have been regarded as a mad enthusiast.

In common with many other excellent persons, Priestley believed that
man is capable of reaching, and will eventually attain, perfection.
If the temperature of space presented no obstacle, I should be glad
to entertain the same idea; but judging from the past progress of our
species, I am afraid that the globe will have cooled down so far,
before the advent of this natural millennium, that we shall be, at
best, perfected Esquimaux. For all practical purposes, however, it
is enough that man may visibly improve his condition in the course
of a century or so. And, if the picture of the state of things
in Priestley’s time, which I have just drawn, have any pretence
to accuracy, I think it must be admitted that there has been a
considerable change for the better.

I need not advert to the well-worn topic of material advancement, in
a place in which the very stones testify to that progress—in the town
of Watt and of Boulton. I will only remark, in passing, that material
advancement has its share in moral and intellectual progress. Becky
Sharp’s acute remark that it is not difficult to be virtuous on ten
thousand a year, has its application to nations; and it is futile to
expect a hungry and squalid population to be anything but violent and
gross. But as regards other than material welfare, although perfection
is not yet in sight—even from the mast-head—it is surely true that
things are much better than they were.

Take the upper and middle classes as a whole, and it may be said
that open immorality and gross intemperance have vanished. Four and
six bottle men are as extinct as the dodo. Women of good repute
do not gamble, and talk modelled upon Dean Swift’s “Art of Polite
Conversation” would be tolerated in no decent kitchen.

Members of the legislature are not to be bought; and constituents are
awakening to the fact that votes must not be sold—even for such trifles
as rabbits and tea and cake. Political power has passed into the hands
of the masses of the people. Those whom Priestley calls their servants
have recognised their position, and have requested the master to be
so good as to go to school and fit himself for the administration of
his property. No civil disability attaches to any one on theological
grounds, and the highest offices of the state are open to Papist, Jew,
or Secularist.[27]

Whatever men’s opinions as to the policy of Establishment, no one
can hesitate to admit that the clergy of the Church are men of pure
life and conversation, zealous in the discharge of their duties; and,
at present, apparently, more bent on prosecuting one another than
on meddling with Dissenters. Theology itself has broadened so much,
that Anglican divines put forward doctrines more liberal than those
of Priestley; and, in our state-supported churches, one listener may
hear a sermon to which Bossuet might have given his approbation, while
another may hear a discourse in which Socrates would find nothing new.

But great as these changes may be, they sink into insignificance
beside the progress of physical science, whether we consider the
improvement of methods of investigation, or the increase in bulk of
solid knowledge. Consider that the labours of Laplace, of Young, of
Davy, and of Faraday; of Cuvier, of Lamarck, and of Robert Brown; of
Von Baer, and of Schwann; of Smith and of Hutton, have all been carried
on since Priestley discovered oxygen; and consider that they are now
things of the past, concealed by the industry of those who have built
upon them, as the first founders of a coral reef are hidden beneath the
life’s work of their successors; consider that the methods of physical
science are slowly spreading into all investigations, and that proofs
as valid as those required by her canons of investigation, are being
demanded of all doctrines which ask for men’s assent; and you will
have a faint image of the astounding difference in this respect between
the nineteenth century and the eighteenth.

If we ask what is the deeper meaning of all these vast changes, I
think there can be but one reply. They mean that reason has asserted
and exercised her primacy over all provinces of human activity: that
ecclesiastical authority has been relegated to its proper place; that
the good of the governed has been finally recognised as the end of
government, and the complete responsibility of governors to the people
as its means; and that the dependence of natural phenomena in general,
on the laws of action of what we call matter has become an axiom.

But it was to bring these things about, and to enforce the recognition
of these truths, that Joseph Priestley laboured. If the nineteenth
century is other and better than the eighteenth, it is, in great
measure, to him and to such men as he, that we owe the change. If the
twentieth century is to be better than the nineteenth, it will be
because there are among us men who walk in Priestley’s footsteps.

Such men are not those whom their own generation delights to honour;
such men, in fact, rarely trouble themselves about honour, but ask,
in another spirit than Falstaff’s, “What is honour? Who hath it? He
that died o’ Wednesday.” But whether Priestley’s lot be theirs, and a
future generation, in justice and in gratitude, set up their statues;
or whether their names and fame are blotted out from remembrance,
their work will live as long as time endures. To all eternity, the
sum of truth and right will have been increased by their means; to all
eternity, falsehood and injustice will be the weaker because they have
lived.




VI.

ON THE METHOD OF ZADIG:

RETROSPECTIVE PROPHECY AS A FUNCTION OF SCIENCE.

  “Une marque plus sûre que toutes celles de Zadig”—CUVIER.[28]


It is a 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 plains. 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 method 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 as much applies 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 to 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 arguments 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 _à 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 palætiological, 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.

Archæology, 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 archæology, 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 do now. Nay, even physical astronomy,
in so far as it takes us back to the uttermost point of time which
palætiological science can reach, is founded upon the same assumption.
If the law of gravitation ever failed to be true, even to the smallest
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
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[29] 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 Asia Minor 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
Palæontology.

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-earth 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 naturæ_.

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 palæontology, 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 palæontologist are based.

Abundant illustrations of this truth will occur to every one who is
familiar with palæontology; 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 apical
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 cuttle-fish 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 _Spirulæ_. The palæontologist 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 having 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
palæontology—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 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 opération se fit en présence de quelques personnes à
qui j’en avais annoncé d’avance le résultat, dans l’intention de leur
prouver par le fait la justice de nos théories zoologiques; puisque le
vrai cachet d’une théorie est sans contredit la faculté qu’elle donne
de prévoir les phénomènes.”

In the “Ossemens fossiles” Cuvier leaves his paper just as it first
appeared in the “Annales du Muséum,” 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,”
however like they might have been to 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
palæontological 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 living 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.




VII.

ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE
VEGETABLE KINGDOMS.


In the whole history of science there is nothing more remarkable than
the rapidity of the growth of biological knowledge within the last
half-century, and the extent of the modification which has thereby been
effected in some of the fundamental conceptions of the naturalist.

In the second edition of the “Règne Animal,” published in 1828,
Cuvier devotes a special section to the “Division of Organised Beings
into Animals and Vegetables,” in which the question is treated with
that comprehensiveness of knowledge and clear critical judgment
which characterise his writings, and justify us in regarding them
as representative expressions of the most extensive, if not the
profoundest, knowledge of his time. He tells us that living beings have
been subdivided from the earliest times into _animated beings_, which
possess sense and motion, and _inanimated beings_, which are devoid of
these functions, and simply vegetate.

Although the roots of plants direct themselves towards moisture, and
their leaves towards air and light,—although the parts of some plants
exhibit oscillating movements without any perceptible cause, and the
leaves of others retract when touched,—yet none of these movements
justify the ascription to plants of perception or of will. From the
mobility of animals, Cuvier, with his characteristic partiality for
teleological reasoning, deduces the necessity of the existence in them
of an alimentary cavity, or reservoir of food, whence their nutrition
may be drawn by the vessels, which are a sort of internal roots; and,
in the presence of this alimentary cavity, he naturally sees the
primary and the most important distinction between animals and plants.

Following out his teleological argument, Cuvier remarks that the
organisation of this cavity and its appurtenances must needs vary
according to the nature of the aliment, and the operations which it
has to undergo, before it can be converted into substances fitted for
absorption; while the atmosphere and the earth supply plants with
juices ready prepared, and which can be absorbed immediately. As the
animal body required to be independent of heat and of the atmosphere,
there were no means by which the motion of its fluids could be produced
by internal causes. Hence arose the second great distinctive character
of animals, or the circulatory system, which is less important than the
digestive, since it was unnecessary, and therefore is absent, in the
more simple animals.

Animals further needed muscles for locomotion and nerves for
sensibility. Hence, says Cuvier, it was necessary that the chemical
composition of the animal body should be more complicated than that of
the plant; and it is so, inasmuch as an additional substance, nitrogen,
enters into it as an essential element; while, in plants, nitrogen is
only accidentally joined with the three other fundamental constituents
of organic beings—carbon, hydrogen, and oxygen. Indeed, he afterwards
affirms that nitrogen is peculiar to animals; and herein he places the
third distinction between the animal and the plant. The soil and the
atmosphere supply plants with water, composed of hydrogen and oxygen;
air, consisting of nitrogen and oxygen; and carbonic acid, containing
carbon and oxygen. They retain the hydrogen and the carbon, exhale the
superfluous oxygen, and absorb little or no nitrogen. The essential
character of vegetable life is the exhalation of oxygen, which is
effected through the agency of light. Animals, on the contrary,
derive their nourishment either directly or indirectly from plants.
They get rid of the superfluous hydrogen and carbon, and accumulate
nitrogen. The relations of plants and animals to the atmosphere are
therefore inverse. The plant withdraws water and carbonic acid from
the atmosphere, the animal contributes both to it. Respiration—that
is, the absorption of oxygen and the exhalation of carbonic acid—is
the specially animal function of animals, and constitutes their fourth
distinctive character.

Thus wrote Cuvier in 1828. But, in the fourth and fifth decades of
this century, the greatest and most rapid revolution which biological
science has ever undergone was effected by the application of the
modern microscope to the investigation of organic structure; by the
introduction of exact and easily manageable methods of conducting the
chemical analysis of organic compounds; and finally, by the employment
of instruments of precision for the measurement of the physical forces
which are at work in the living economy.

That the semi-fluid contents (which we now term protoplasm) of the
cells of certain plants, such as the _Charæ_, are in constant and
regular motion, was made out by Bonaventura Corti a century ago; but
the fact, important as it was, fell into oblivion, and had to be
rediscovered by Treviranus in 1807. Robert Brown noted the more complex
motions of the protoplasm in the cells of _Tradescantia_ in 1831; and
now such movements of the living substance of plants are well known to
be some of the most widely-prevalent phenomena of vegetable life.

Agardh, and other of the botanists of Cuvier’s generation, who occupied
themselves with the lower plants, had observed that, under particular
circumstances, the contents of the cells of certain water-weeds were
set free, and moved about with considerable velocity, and with all the
appearances of spontaneity, as locomotive bodies, which, from their
similarity to animals of simple organisation, were called “zoospores.”
Even as late as 1845, however, a botanist of Schleiden’s eminence dealt
very sceptically with these statements; and his scepticism was the more
justified, since Ehrenberg, in his elaborate and comprehensive work
on the _Infusoria_, had declared the greater number of what are now
recognised as locomotive plants to be animals.

At the present day, innumerable plants and free plant cells are known
to pass the whole or part of their lives in an actively locomotive
condition, in no wise distinguishable from that of one of the simpler
animals; and, while in this condition, their movements are, to all
appearance, as spontaneous—as much the product of volition—as those of
such animals.

Hence the teleological argument for Cuvier’s first diagnostic
character—the presence in animals of an alimentary cavity, or internal
pocket, in which they can carry about their nutriment—has broken
down, so far, at least, as his mode of stating it goes. And, with the
advance of microscopic anatomy, the universality of the fact itself
among animals has ceased to be predicable. Many animals of even complex
structure, which live parasitically within others, are wholly devoid
of an alimentary cavity. Their food is provided for them, not only
ready cooked, but ready digested, and the alimentary canal, become
superfluous, has disappeared. Again, the males of most Rotifers have no
digestive apparatus; as a German naturalist has remarked, they devote
themselves entirely to the “Minnedienst,” and are to be reckoned among
the few realisations of the Byronic ideal of a lover. Finally, amidst
the lowest forms of animal life, the speck of gelatinous protoplasm,
which constitutes the whole body, has no permanent digestive cavity or
mouth, but takes in its food anywhere; and digests, so to speak, all
over its body.

But although Cuvier’s leading diagnosis of the animal from the plant
will not stand a strict test, it remains one of the most constant of
the distinctive characters of animals. And, if we substitute for the
possession of an alimentary cavity, the power of taking solid nutriment
into the body and there digesting it, the definition so changed
will cover all animals, except certain parasites, and the few and
exceptional cases of non-parasitic animals which do not feed at all. On
the other hand, the definition thus amended will exclude all ordinary
vegetable organisms.

Cuvier himself practically gives up his second distinctive mark when he
admits that it is wanting in the simpler animals.

The third distinction is based on a completely erroneous conception of
the chemical differences and resemblances between the constituents of
animal and vegetable organisms, for which Cuvier is not responsible,
as it was current among contemporary chemists. It is now established
that nitrogen is as essential a constituent of vegetable as of animal
living matter; and that the latter is, chemically speaking, just as
complicated as the former. Starchy substances, cellulose and sugar,
once supposed to be exclusively confined to plants, are now known to
be regular and normal products of animals. Amylaceous and saccharine
substances are largely manufactured, even by the highest animals;
cellulose is widespread as a constituent of the skeletons of the lower
animals; and it is probable that amyloid substances are universally
present in the animal organism, though not in the precise form of
starch.

Moreover, although it remains true that there is an inverse relation
between the green plant in sunshine and the animal, in so far as, under
these circumstances, the green plant decomposes carbonic acid and
exhales oxygen, while the animal absorbs oxygen and exhales carbonic
acid; yet, the exact researches of the modern chemical investigators
of the physiological processes of plants have clearly demonstrated the
fallacy of attempting to draw any general distinction between animals
and vegetables on this ground. In fact, the difference vanishes with
the sunshine, even in the case of the green plant; which, in the dark,
absorbs oxygen and gives out carbonic acid like any animal.[30] On
the other hand, those plants, such as the fungi, which contain no
chlorophyll and are not green, are always, so far as respiration is
concerned, in the exact position of animals. They absorb oxygen and
give out carbonic acid.

Thus, by the progress of knowledge, Cuvier’s fourth distinction
between the animal and the plant has been as completely invalidated as
the third and second; and even the first can be retained only in a
modified form and subject to exceptions.

But has the advance of biology simply tended to break down old
distinctions, without establishing new ones?

With a qualification, to be considered presently, the answer to this
question is undoubtedly in the affirmative. The famous researches of
Schwann and Schleiden in 1837 and the following years, founded the
modern science of histology, or that branch of anatomy which deals
with the ultimate visible structure of organisms, as revealed by
the microscope; and, from that day to this, the rapid improvement
of methods of investigation, and the energy of a host of accurate
observers, have given greater and greater breadth and firmness to
Schwann’s great generalisation, that a fundamental unity of structure
obtains in animals and plants; and that, however diverse may be the
fabrics, or _tissues_, of which their bodies are composed, all these
varied structures result from the metamorphosis of morphological units
(termed _cells_, in a more general sense than that in which the word
“cells” was at first employed), which are not only similar in animals
and in plants respectively, but present a close resemblance, when those
of animals and those of plants are compared together.

The contractility which is the fundamental condition of locomotion,
has not only been discovered to exist far more widely among plants
than was formerly imagined; but, in plants, the act of contraction has
been found to be accompanied, as Dr. Burdon Sanderson’s interesting
investigations have shown, by a disturbance of the electrical state of
the contractile substance, comparable to that which was found by Du
Bois Reymond to be a concomitant of the activity of ordinary muscle in
animals.

Again, I know of no test by which the reaction of the leaves of the
Sundew and of other plants to stimuli, so fully and carefully studied
by Mr. Darwin, can be distinguished from those acts of contraction
following upon stimuli, which are called “reflex” in animals.

On each lobe of the bilobed leaf of Venus’s fly trap (_Dionæa
muscipula_) are three delicate filaments which stand out at right angle
from the surface of the leaf. Touch one of them with the end of a fine
human hair and the lobes of the leaf instantly close together[31] in
virtue of an act of contraction of part of their substance, just as the
body of a snail contracts into its shell when one of its “horns” is
irritated.

The reflex action of the snail is the result of the presence of a
nervous system in the animal. A molecular change takes place in the
nerve of the tentacle, is propagated to the muscles by which the body
is retracted, and causing them to contract, the act of retraction
is brought about. Of course the similarity of the acts does not
necessarily involve the conclusion that the mechanism by which they are
effected is the same; but it suggests a suspicion of their identity
which needs careful testing.

The results of recent inquiries into the structure of the nervous
system of animals converge towards the conclusion that the nerve
fibres, which we have hitherto regarded as ultimate elements of nervous
tissue, are not such, but are simply the visible aggregations of vastly
more attenuated filaments, the diameter of which dwindles down to the
limits of our present microscopic vision, greatly as these have been
extended by modern improvements of the microscope; and that a nerve
is, in its essence, nothing but a linear tract of specially modified
protoplasm between two points of an organism—one of which is able to
affect the other by means of the communication so established. Hence,
it is conceivable that even the simplest living being may possess a
nervous system. And the question whether plants are provided with a
nervous system or not, thus acquires a new aspect, and presents the
histologist and physiologist with a problem of extreme difficulty,
which must be attacked from a new point of view and by the aid of
methods which have yet to be invented.

Thus it must be admitted that plants may be contractile and locomotive;
that, while locomotive, their movements may have as much appearance
of spontaneity as those of the lowest animals; and that many exhibit
actions, comparable to those which are brought about by the agency of a
nervous system in animals. And it must be allowed to be possible that
further research may reveal the existence of something comparable to a
nervous system in plants. So that I know not where we can hope to find
any absolute distinction between animals and plants, unless we return
to their mode of nutrition, and inquire whether certain differences of
a more occult character than those imagined to exist by Cuvier, and
which certainly hold good for the vast majority of animals and plants,
are of universal application.

A bean may be supplied with water in which salts of ammonia and
certain other mineral salts are dissolved in due proportion; with
atmospheric air containing its ordinary minute dose of carbonic acid;
and with nothing else but sunlight and heat. Under these circumstances,
unnatural as they are, with proper management, the bean will thrust
forth its radicle and its plumule; the former will grow down into
roots, the latter grow up into the stem and leaves of a vigorous bean
plant; and this plant will, in due time, flower and produce its crop of
beans, just as if it were grown in the garden or in the field.

The weight of the nitrogenous protein compounds, of the oily, starchy,
saccharine and woody substances contained in the full-grown plant
and its seeds, will be vastly greater than the weight of the same
substances contained in the bean from which it sprang. But nothing has
been supplied to the bean save water, carbonic acid, ammonia, potash,
lime, iron, and the like, in combination with phosphoric, sulphuric,
and other acids. Neither protein, nor fat, nor starch, nor sugar, nor
any substance in the slightest degree resembling them, has formed part
of the food of the bean. But the weights of the carbon, hydrogen,
oxygen, nitrogen, phosphorus, sulphur, and other elementary bodies
contained in the bean-plant, and in the seeds which it produces, are
exactly equivalent to the weights of the same elements which have
disappeared from the materials supplied to the bean during its growth.
Whence it follows that the bean has taken in only the raw materials of
its fabric, and has manufactured them into bean stuffs.

The bean has been able to perform this great chemical feat by the
help of its green colouring matter, or chlorophyll; for it is only
the green parts of the plant which, under the influence of sunlight,
have the marvellous power of decomposing carbonic acid, setting free
the oxygen and laying hold of the carbon which it contains. In fact,
the bean obtains two of the absolutely indispensable elements of its
substance from two distinct sources; the watery solution, in which its
roots are plunged, contains nitrogen but no carbon; the air, to which
the leaves are exposed, contains carbon, but its nitrogen is in the
state of a free gas, in which condition the bean can make no use of
it;[32] and the chlorophyll[33] is the apparatus by which the carbon is
extracted from the atmospheric carbonic acid—the leaves being the chief
laboratories in which this operation is effected.

The great majority of conspicuous plants are, as everybody knows,
green; and this arises from the abundance of their chlorophyll.
The few which contain no chlorophyll and are colourless, are unable
to extract the carbon which they require from atmospheric carbonic
acid, and lead a parasitic existence upon other plants; but it by no
means follows, often as the statement has been repeated, that the
manufacturing power of plants depends on their chlorophyll, and its
interaction with the rays of the sun. On the contrary, it is easily
demonstrated, as Pasteur first proved, that the lowest fungi, devoid
of chlorophyll, or of any substitute for it, as they are, nevertheless
possess the characteristic manufacturing powers of plants in a very
high degree. Only it is necessary that they should be supplied with
a different kind of raw material; as they cannot extract carbon from
carbonic acid, they must be furnished with something else that contains
carbon. Tartaric acid is such a substance; and if a single spore of
the commonest and most troublesome of moulds—_Penicillium_—be sown
in a saucerful of water, in which tartrate of ammonia, with a small
percentage of phosphates and sulphates is contained, and kept warm,
whether in the dark or exposed to light, it will, in a short time, give
rise to a thick crust of mould, which contains many million times the
weight of the original spore, in protein compounds and cellulose. Thus
we have a very wide basis of fact for the generalisation that plants
are essentially characterised by their manufacturing capacity—by their
power of working up mere mineral matters into complex organic compounds.

Contrariwise, there is a no less wide foundation for the
generalisation that animals, as Cuvier puts it, depend directly or
indirectly upon plants for the materials of their bodies; that is,
either they are herbivorous, or they eat other animals which are
herbivorous.

But for what constituents of their bodies are animals thus dependent
upon plants? Certainly not for their horny matter; nor for chondrin,
the proximate chemical element of cartilage; nor for gelatine; nor for
syntonin, the constituent of muscle; nor for their nervous or biliary
substances; nor for their amyloid matters; nor, necessarily, for their
fats.

It can be experimentally demonstrated that animals can make these for
themselves. But that which they cannot make, but must, in all known
cases, obtain directly or indirectly from plants, is the peculiar
nitrogenous matter, protein. Thus the plant is the ideal _prolétaire_
of the living world, the worker who produces; the animal, the ideal
aristocrat, who mostly occupies himself in consuming, after the manner
of that noble representative of the line of Zähdarm, whose epitaph is
written in _Sartor Resartus_.

Here is our last hope of finding a sharp line of demarcation between
plants and animals; for, as I have already hinted, there is a border
territory between the two kingdoms, a sort of no-man’s-land, the
inhabitants of which certainly cannot be discriminated and brought to
their proper allegiance in any other way.

Some months ago, Professor Tyndall asked me to examine a drop of
infusion of hay, placed under an excellent and powerful microscope,
and to tell him what I thought some organisms visible in it were.
I looked and observed, in the first place, multitudes of _Bacteria_
moving about with their ordinary intermittent spasmodic wriggles. As
to the vegetable nature of these there is now no doubt. Not only does
the close resemblance of the _Bacteria_ to unquestionable plants,
such as the _Oscillatoriæ_, and lower forms of _Fungi_, justify this
conclusion, but the manufacturing test settles the question at once. It
is only needful to add a minute drop of fluid containing _Bacteria_,
to water in which tartrate, phosphate, and sulphate of ammonia are
dissolved; and, in a very short space of time, the clear fluid becomes
milky by reason of their prodigious multiplication, which, of course,
implies the manufacture of living Bacterium-stuff out of these merely
saline matters.

But other active organisms, very much larger than the _Bacteria_,
attaining in fact the comparatively gigantic dimensions of 1/3000 of an
inch or more, incessantly crossed the field of view. Each of these had
a body shaped like a pear, the small end being slightly incurved and
produced into a long curved filament, or _cilium_, of extreme tenuity.
Behind this, from the concave side of the incurvation, proceeded
another long cilium, so delicate as to be discernible only by the use
of the highest powers and careful management of the light. In the
centre of the pear-shaped body a clear round space could occasionally
be discerned, but not always; and careful watching showed that this
clear vacuity appeared gradually, and then shut up and disappeared
suddenly, at regular intervals. Such a structure is of common
occurrence among the lowest plants and animals, and is known as a
_contractile vacuole_.

The little creature thus described sometimes propelled itself with
great activity, with a curious rolling motion, by the lashing of the
front cilium, while the second cilium trailed behind; sometimes it
anchored itself by the hinder cilium and was spun round by the working
of the other, its motions resembling those of an anchor buoy in a heavy
sea. Sometimes, when two were in full career towards one another, each
would appear dexterously to get out of the other’s way; sometimes a
crowd would assemble and jostle one another, with as much semblance of
individual effort as a spectator on the Grands Mulets might observe
with a telescope among the specks representing men in the valley of
Chamounix.

The spectacle, though always surprising, was not new to me. So my
reply to the question put to me was, that these organisms were what
biologists call _Monads_, and though they might be animals, it was
also possible that they might, like the _Bacteria_, be plants. My
friend received my verdict with an expression which showed a sad want
of respect for authority. He would as soon believe that a sheep was
a plant. Naturally piqued by this want of faith, I have thought a
good deal over the matter; and as I still rest in the lame conclusion
I originally expressed, and must even now confess that I cannot
certainly say whether this creature is an animal or a plant, I think
it may be well to state the grounds of my hesitation at length. But,
in the first place, in order that I may conveniently distinguish
this “Monad” from the multitude of other things which go by the same
designation, I must give it a name of its own. I think (though, for
reasons which need not be stated at present, I am not quite sure)
that it is identical with the species _Monas lens_, as defined by the
eminent French microscopist Dujardin, though his magnifying power was
probably insufficient to enable him to see that it is curiously like
a much larger form of monad which he has named _Heteromita_. I shall,
therefore, call it not _Monas_, but _Heteromita lens_.

I have been unable to devote to my _Heteromita_ the prolonged study
needful to work out its whole history, which would involve weeks, or
it may be months, of unremitting attention. But I the less regret this
circumstance, as some remarkable observations recently published by
Messrs. Dallinger and Drysdale[34] on certain Monads, relate, in part,
to a form so similar to my _Heteromita lens_, that the history of the
one may be used to illustrate that of the other. These most patient
and painstaking observers, who employed the highest attainable powers
of the microscope and, relieving one another, kept watch day and night
over the same individual monads, have been enabled to trace out the
whole history of their _Heteromita_; which they found in infusions of
the heads of fishes of the Cod tribe.

Of the four monads described and figured by these investigators,
one, as I have said, very closely resembles _Heteromita lens_ in
every particular, except that it has a separately distinguishable
central particle or “nucleus,” which is not certainly to be made out
in _Heteromita lens_; and that nothing is said by Messrs. Dallinger
and Drysdale of the existence of a contractile vacuole in this monad,
though they describe it in another.

Their _Heteromita_, however, multiplied rapidly by fission. Sometimes
a transverse constriction appeared; the hinder half developed a new
cilium, and the hinder cilium gradually split from its base to its
free end, until it was divided into two; a process which, considering
the fact that this fine filament cannot be much more than 1/100000
of an inch in diameter, is wonderful enough. The constriction of the
body extended inwards until the two portions were united by a narrow
isthmus; finally, they separated and each swam away by itself, a
complete _Heteromita_, provided with its two cilia. Sometimes the
constriction took a longitudinal direction, with the same ultimate
result. In each case the process occupied not more than six or seven
minutes. At this rate, a single _Heteromita_ would give rise to a
thousand like itself in the course of an hour, to about a million in
two hours, and to a number greater than the generally assumed number
of human beings now living in the world in three hours; or, if we give
each _Heteromita_ an hour’s enjoyment of individual existence, the same
result will be obtained in about a day. The apparent suddenness of the
appearance of multitudes of such organisms as these, in any nutritive
fluid to which one obtains access, is thus easily explained.

During these processes of multiplication by fission, the _Heteromita_
remains active; but sometimes another mode of fission occurs. The body
becomes rounded and quiescent, or nearly so; and, while in this resting
state, divides into two portions, each of which is rapidly converted
into an active _Heteromita_.

A still more remarkable phenomenon is that kind of multiplication
which is preceded by the union of two monads, by a process which is
termed _conjugation_. Two active _Heteromitæ_ become applied to one
another, and then slowly and gradually coalesce into one body. The
two nuclei run into one; and the mass resulting from the conjugation
of the two _Heteromitæ_, thus fused together, has a triangular form.
The two pairs of cilia are to be seen, for some time, at two of the
angles, which answer to the small ends of the conjoined monads; but
they ultimately vanish, and the twin organism, in which all visible
traces of organisation have disappeared, falls into a state of rest.
Sudden wave-like movements of its substance next occur; and, in a short
time, the apices of the triangular mass burst, and give exit to a dense
yellowish, glairy fluid, filled with minute granules. This process,
which, it will be observed, involves the actual confluence and mixture
of the substance of two distinct organisms, is effected in the space of
about two hours.

The authors whom I quote say that they “cannot express” the excessive
minuteness of the granules in question, and they estimate their
diameter at less than 1/200000 of an inch. Under the highest powers
of the microscope at present applicable such specks are hardly
discernible. Nevertheless, particles of this size are massive when
compared to physical molecules; whence there is no reason to doubt
that each, small as it is, may have a molecular structure sufficiently
complex to give rise to the phenomena of life. And, as a matter of
fact, by patient watching of the place at which these infinitesimal
living particles were discharged, our observers assured themselves
of their growth and development into new monads. These, in about
four hours from their being set free, had attained a sixth of the
length of the parent, with the characteristic cilia, though at
first they were quite motionless; and, in four hours more, they had
attained the dimensions and exhibited all the activity of the adult.
These inconceivably minute particles are therefore the germs of the
_Heteromita_; and from the dimensions of these germs it is easily
shown that the body formed by conjugation may, at a low estimate,
have given exit to thirty thousand of them; a result of a matrimonial
process whereby the contracting parties, without a metaphor, “become
one flesh,” enough to make a Malthusian despair of the future of the
Universe.

I am not aware that the investigators from whom I have borrowed this
history have endeavoured to ascertain whether their monads take solid
nutriment or not; so that though they help us very much to fill up the
blanks in the history of my _Heteromita_, their observations throw no
light on the problem we are trying to solve—Is it an animal or is it a
plant?

Undoubtedly it is possible to bring forward very strong arguments in
favour of regarding _Heteromita_ as a plant.

For example, there is a Fungus, an obscure and almost microscopic
mould, termed _Peronospora infestans_. Like many other Fungi, the
_Peronosporæ_ are parasitic upon other plants; and this particular
_Peronospora_ happens to have attained much notoriety and political
importance, in a way not without a parallel in the career of notorious
politicians, namely, by reason of the frightful mischief it has
done to mankind. For it is this _Fungus_ which is the cause of the
potato disease; and, therefore, _Peronospora infestans_ (doubtless of
exclusively Saxon origin, though not accurately known to be so) brought
about the Irish famine. The plants afflicted with the malady are found
to be infested by a mould, consisting of fine tubular filaments, termed
_hyphæ_, which burrow through the substance of the potato plant, and
appropriate to themselves the substance of their host; while, at the
same time, directly or indirectly, they set up chemical changes by
which even its woody framework becomes blackened, sodden, and withered.

In structure, however, the _Peronospora_ is as much a mould as the
common _Penicillium_; and just as the _Penicillium_ multiplies by the
breaking up of its hyphæ into separate rounded bodies, the spores;
so, in the _Peronospora_, certain of the hyphæ grow out into the air
through the interstices of the superficial cells of the potato plant,
and develop spores. Each of these hyphæ usually gives off several
branches. The ends of the branches dilate and become closed sacs, which
eventually drop off as spores. The spores falling on some part of the
same potato plant, or carried by the wind to another, may at once
germinate, throwing out tubular prolongations which become hyphæ, and
burrow into the substance of the plant attacked. But, more commonly,
the contents of the spore divide into six or eight separate portions.
The coat of the spore gives way, and each portion then emerges as an
independent organism, which has the shape of a bean, rather narrower at
one end than the other, convex on one side, and depressed or concave on
the opposite. From the depression, two long and delicate cilia proceed,
one shorter than the other, and directed forwards. Close to the origin
of these cilia, in the substance of the body, is a regularly pulsating,
contractile vacuole. The shorter cilium vibrates actively, and effects
the locomotion of the organism, while the other trails behind; the
whole body rolling on its axis with its pointed end forwards.

The eminent botanist, De Bary, who was not thinking of our problem,
tells us, in describing the movements of these “Zoospores,” that, as
they swim about, “Foreign bodies are carefully avoided, and the whole
movement has a deceptive likeness to the voluntary changes of place
which are observed in microscopic animals.”

After swarming about in this way in the moisture on the surface of
a leaf or stem (which, film though it may be, is an ocean to such a
fish) for half an hour, more or less, the movement of the zoospore
becomes slower, and is limited to a slow turning upon its axis, without
change of place. It then becomes quite quiet, the cilia disappear, it
assumes a spherical form, and surrounds itself with a distinct, though
delicate, membranous coat. A protuberance then grows out from one side
of the sphere, and rapidly increasing in length, assumes the character
of a hypha. The latter penetrates into the substance of the potato
plant, either by entering a stomate, or by boring through the wall of
an epidermic cell, and ramifies, as a mycelium, in the substance of
the plant, destroying the tissues with which it comes in contact. As
these processes of multiplication take place very rapidly, millions of
spores are soon set free from a single infested plant; and, from their
minuteness, they are readily transported by the gentlest breeze. Since,
again, the zoospores set free from each spore, in virtue of their
powers of locomotion, swiftly disperse themselves over the surface, it
is no wonder that the infection, once started, soon spreads from field
to field, and extends its ravages over a whole country.

However, it does not enter into my present plan to treat of the
potato disease, instructively as its history bears upon that of other
epidemics; and I have selected the case of the _Peronospora_ simply
because it affords an example of an organism, which, in one stage of
its existence, is truly a “Monad,” indistinguishable by any important
character from our _Heteromita_, and extraordinarily like it in some
respects. And yet this “Monad” can be traced, step by step, through the
series of metamorphoses which I have described, until it assumes the
features of an organism, which is as much a plant as is an oak or an
elm.

Moreover, it would be possible to pursue the analogy farther. Under
certain circumstances, a process of conjugation takes place in the
_Peronospora_. Two separate portions of its protoplasm become fused
together, surround themselves with a thick coat, and give rise to a
sort of vegetable egg called an _oospore_. After a period of rest,
the contents of the oospore break up into a number of zoospores like
those already described, each of which, after a period of activity,
germinates in the ordinary way. This process obviously corresponds
with the conjugation and subsequent setting free of germs in the
_Heteromita_.

But it may be said that the _Peronospora_ is, after all, a questionable
sort of plant; that it seems to be wanting in the manufacturing power,
selected as the main distinctive character of vegetable life; or, at
any rate, that there is no proof that it does not get its protein
matter ready made from the potato plant.

Let us, therefore, take a case which is not open to these objections.

There are some small plants known to botanists as members of the genus
_Coleochæte_, which, without being truly parasitic, grow upon certain
water-weeds, as lichens grow upon trees. The little plant has the form
of an elegant green star, the branching arms of which are divided into
cells. Its greenness is due to its chlorophyll, and it undoubtedly
has the manufacturing power in full degree, decomposing carbonic acid
and setting oxygen free, under the influence of sunlight. But the
protoplasmic contents of some of the cells of which the plant is made
up occasionally divide, by a method similar to that which effects the
division of the contents of the _Peronospora_ spore; and the severed
portions are then set free as active monad-like zoospores. Each is oval
and is provided at one extremity with two long active cilia. Propelled
by these, it swims about for a longer or shorter time, but at length
comes to a state of rest and gradually grows into a _Coleochæte_.
Moreover, as in the _Peronospora_, conjugation may take place and
result in an oospore; the contents of which divide and are set free as
monadiform germs.

If the whole history of the zoospores of _Peronospora_, and of
_Coleochæte_ were unknown, they would undoubtedly be classed among
“Monads” with the same right as _Heteromita_; why then may not
_Heteromita_ be a plant, even though the cycle of forms through
which it passes shows no terms quite so complex as those which occur
in _Peronospora_ and _Coleochæte_? And, in fact, there are some
green organisms, in every respect characteristically plants, such
as _Chlamydomonas_, and the common _Volvox_, or so-called “Globe
animalcule,” which run through a cycle of forms of just the same simple
character as those of _Heteromita_.

The name of _Chlamydomonas_ is applied to certain microscopic green
bodies, each of which consists of a protoplasmic central substance
invested by a structureless sac. The latter contains cellulose, as
in ordinary plants; and the chlorophyll which gives the green colour
enables the _Chlamydomonas_ to decompose carbonic acid and fix carbon
as they do. Two long cilia protrude through the cell-wall, and effect
the rapid locomotion of this “monad,” which, in all respects except its
mobility, is characteristically a plant. Under ordinary circumstances,
the _Chlamydomonas_ multiplies by simple fission, each splitting
into two or into four parts, which separate and become independent
organisms. Sometimes, however, the _Chlamydomonas_ divides into eight
parts, each of which is provided with four instead of two cilia. These
“zoospores” conjugate in pairs, and give rise to quiescent bodies,
which multiply by division, and eventually pass into the active state.

Thus, so far as outward form and the general character of the cycle
of modifications, through which the organism passes in the course of
its life, are concerned, the resemblance between _Chlamydomonas_ and
_Heteromita_ is of the closest description. And on the face of the
matter there is no ground for refusing to admit that _Heteromita_ may
be related to _Chlamydomonas_, as the colourless fungus is to the green
alga. _Volvox_ may be compared to a hollow sphere, the wall of which
is made up of coherent Chlamydomonads; and which progresses with a
rotating motion effected by the paddling of the multitudinous pairs of
cilia which project from its surface. Each _Volvox_monad, moreover,
possesses a red pigment spot, like the simplest form of eye known among
animals. The methods of fissive multiplication and of conjugation
observed in the monads of this locomotive globe are essentially similar
to those observed in _Chlamydomonas_; and, though a hard battle has
been fought over it, _Volvox_ is now finally surrendered to the
Botanists.

Thus there is really no reason why _Heteromita_ may not be a plant; and
this conclusion would be very satisfactory, if it were not equally easy
to show that there is really no reason why it should not be an animal.
For there are numerous organisms presenting the closest resemblance to
_Heteromita_, and, like it, grouped under the general name of “Monads,”
which, nevertheless, can be observed to take in solid nutriment, and
which, therefore, have a virtual, if not an actual, mouth and digestive
cavity, and thus come under Cuvier’s definition of an animal. Numerous
forms of such animals have been described by Ehrenberg, Dujardin, H.
James Clark, and other writers on the _Infusoria_. Indeed, in another
infusion of hay in which my _Heteromita lens_ occurred, there were
innumerable infusorial animalcules belonging to the well-known species
_Colpoda cucullus_.[35]

Full-sized specimens of this animalcule attain a length of between
1/300 or 1/400 of an inch, so that it may have ten times the length
and a thousand times the mass of a _Heteromita_. In shape, it is
not altogether unlike _Heteromita_. The small end, however, is not
produced into one long cilium, but the general surface of the body is
covered with small actively vibrating ciliary organs, which are only
longest at the small end. At the point which answers to that from which
the two cilia arise in _Heteromita_, there is a conical depression, the
mouth; and, in young specimens, a tapering filament, which reminds one
of the posterior cilium of _Heteromita_, projects from this region.

The body consists of a soft granular protoplasmic substance, the middle
of which is occupied by a large oval mass called the “nucleus;” while,
at its hinder end, is a “contractile vacuole,” conspicuous by its
regular rhythmic appearances and disappearances. Obviously, although
the _Colpoda_ is not a monad, it differs from one only in subordinate
details. Moreover, under certain conditions, it becomes quiescent,
incloses itself in a delicate case or _cyst_, and then divides into
two, four, or more portions, which are eventually set free and swim
about as active _Colpodæ_.

But this creature is an unmistakable animal, and full-sized _Colpodæ_
may be fed as easily as one feeds chickens. It is only needful to
diffuse very finely ground carmine through the water in which they
live, and, in a very short time, the bodies of the _Colpodæ_ are
stuffed with the deeply-coloured granules of the pigment.

And if this were not sufficient evidence of the animality of _Colpoda_,
there comes the fact that it is even more similar to another well-known
animalcule, _Paramæcium_, than it is to a monad. But _Paramæcium_ is
so huge a creature compared with those hitherto discussed—it reaches
1/120 of an inch or more in length—that there is no difficulty in
making out its organisation in detail; and in proving that it is not
only an animal, but that it is an animal which possesses a somewhat
complicated organisation. For example, the surface layer of its body is
different in structure from the deeper parts. There are two contractile
vacuoles, from each of which radiates a system of vessel-like canals;
and not only is there a conical depression continuous with a tube,
which serve as mouth and gullet, but the food ingested takes a definite
course, and refuse is rejected from a definite region. Nothing is
easier than to feed these animals, and to watch the particles of indigo
or carmine accumulate at the lower end of the gullet. From this they
gradually project, surrounded by a ball of water, which at length
passes with a jerk, oddly simulating a gulp, into the pulpy central
substance of the body, there to circulate up one side and down the
other, until its contents are digested and assimilated. Nevertheless,
this complex animal multiplies by division, as the monad does, and,
like the monad, undergoes conjugation. It stands in the same relation
to _Heteromita_ on the animal side, as _Coleochæte_ does on the plant
side. Start from either, and such an insensible series of gradations
leads to the monad that it is impossible to say at any stage of the
progress—here the line between the animal and the plant must be drawn.

There is reason to think that certain organisms which pass through a
monad stage of existence, such as the _Myxomycetes_, are, at one time
of their lives, dependent upon external sources for their protein
matter, or are animals; and, at another period, manufacture it, or are
plants. And seeing that the whole progress of modern investigation is
in favour of the doctrine of continuity, it is a fair and probable
speculation—though only a speculation—that, as there are some plants
which can manufacture protein out of such apparently intractable
mineral matters as carbonic acid, water, nitrate of ammonia, metallic
and earthy salts; while others need to be supplied with their carbon
and nitrogen in the somewhat less raw form of tartrate of ammonia and
allied compounds; so there may be yet others, as is possibly the case
with the true parasitic plants, which can only manage to put together
materials still better prepared—still more nearly approximated to
protein—until we arrive at such organisms as the _Psorospermiæ_ and the
_Panhistophyton_, which are as much animal as vegetable in structure,
but are animal in their dependence on other organisms for their food.

The singular circumstance observed by Meyer, that the _Torula_ of
yeast, though an indubitable plant, still flourishes most vigorously
when supplied with the complex nitrogenous substance, pepsin; the
probability that the _Peronospora_ is nourished directly by the
protoplasm of the potato-plant; and the wonderful facts which have
recently been brought to light respecting insectivorous plants, all
favour this view; and tend to the conclusion that the difference
between animal and plant is one of degree rather than of kind; and that
the problem whether, in a given case, an organism is an animal or a
plant, may be essentially insoluble.




VIII.

ON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART
ATTRIBUTED TO ARISTOTLE.


In all the commentaries upon the “Historia Animalium” which I have met
with, Aristotle’s express and repeated statement, that the heart of
man and the largest animals contains only three cavities, is noted as
a remarkable error. Even Cuvier, who had a great advantage over most
of the commentators in his familiarity with the subject of Aristotle’s
description, and whose habitual caution and moderation seem to desert
him when the opportunity of panegyrising the philosopher presents
itself, is betrayed into something like a sneer on this topic.

  “Du reste il n’attribue à cet organe que trois cavités,
  erreur qui prouve au moins qu’il en avait regardé la
  structure.”[36]

To which remark, what follows will, I think, justify the reply, that it
“prouve au moins” that Cuvier had not given ordinary attention, to say
nothing of the careful study which they deserve, to sundry passages in
the first and the third books of the “Historia” which I proceed to lay
before the reader.

For convenience of reference these passages are marked _A_, _B_, _C_,
etc.[37]

  Book i. 17.—(_A_) “The heart has three cavities, it lies
  above the lung on the division of the windpipe, and has
  a fatty and thick membrane where it is united with the
  great vein and the aorta. It lies upon the aorta, with
  its point down the chest, in all animals that have a
  chest. In all, alike in those that have a chest and in
  those that have none, the foremost part of it is the
  apex. This is often overlooked through the turning upside
  down of the dissection. The rounded end of the heart is
  uppermost, the pointed end of it is largely fleshy and
  thick, and in its cavities there are tendons. In other
  animals which have a chest the heart lies in the middle
  of the chest; in men, more to the left side, between the
  nipples, a little inclined to the left nipple in the
  upper part of the chest. The heart is not large, and its
  general form is not elongated but rounded, except that
  the apex is produced into a point.

  (_B_) “It has, as already stated, three cavities, the
  largest of them is on the right, the smallest on the
  left, the middle-sized one in the middle; they have all,
  also the two small ones, passages (τετρημένας) towards
  the lung, very evidently as respects one of the cavities.
  In the region of the union [with the great vein and the
  aorta] the largest cavity is connected with the largest
  vein (near which is the mesentery); the middle cavity
  with the aorta.

  (_C_) “Canals (πόροι) from the heart pass to the lung and
  divide in the same fashion as the windpipe does, closely
  accompanying those from the windpipe through the whole
  lung. The canals from the heart are uppermost.

  (_D_) “No canal is common [to the branches of the
  windpipe and those of the vein] (οὐδεὶς δ’ ἐστὶ κοινὸς
  πόρος) but through those parts of them which are in
  contact (τὴν σύναψιν) the air passes in and they [the
  πόροι] carry it to the heart.

  (_E_) “One of the canals leads to the right cavity, the
  other to the left.

  (_F_) “Of all the viscera, the heart alone contains blood
  [in itself]. The lung contains blood, not in itself but
  in the veins, the heart in itself; for in each of the
  cavities there is blood; the thinnest is in the middle
  cavity.”

  Book iii. 3.—(_G_) “Two veins lie in the thorax alongside
  the spine, on its inner face; the larger more forwards,
  the smaller behind; the larger more to the right, the
  smaller, which some call _aorta_ (on account of the
  tendinous part of it seen in dead bodies), to the left.
  These take their origin from the heart; they pass entire,
  preserving the nature of veins, through the other viscera
  that they reach; while the heart is rather a part of
  them, and more especially of the anterior and larger one,
  which is continued into veins above and below, while
  between these is the heart.

  (_H_) “All hearts contain cavities, but, in those of very
  small animals, the largest [cavity] is hardly visible,
  those of middling size have another, and the biggest all
  three.

  (_I_) “The point of the heart is directed forwards, as
  was mentioned at first; the largest cavity to the right
  and upper side of it, the smallest to the left, and the
  middle-sized one between these; both of these are much
  smaller than the largest.

  (_K_) “They are all connected by passages (συντέτρηνται)
  with the lung, but, on account of the smallness of the
  canals, this is obscure except in one.

  (_L_) “The great vein proceeds from the largest cavity
  which lies upwards and to the right; next through the
  hollow middle part (διὰ τοῦ κοίλου τοῦ μέσου) it becomes
  vein again, this cavity being a part of the vein in which
  the blood stagnates.

  (_M_) “The aorta [proceeds from] the middle [cavity], but
  not in the same way, for it is connected [with the middle
  cavity] by a much more narrow tube (σύριγγα).

  (_N_) “The [great] vein extends through the heart,
  towards the aorta from the heart.

  (_O_) “The great vein is membranous like skin, the aorta
  narrower than it and very tendinous, and as it extends
  towards the head and the lower parts it becomes narrow
  and altogether tendinous.

  (_P_) “In the first place, a part of the great vein
  extends upwards from the heart towards the lung and
  the attachment of the aorta, the vein being large and
  undivided. It divides into two parts, the one to the
  lung, the other to the spine and the lowest vertebra of
  the neck.

  (_Q_) “The vein which extends to the lung first divides
  into two parts for the two halves of it and then extends
  alongside each tube (σύριγγα) and each passage (τρῆμα),
  the larger beside the larger and the smaller beside the
  smaller, so that no part [of the lung] can be found
  from which a passage (τρῆμα) and a vein are absent.
  The terminations are invisible on account of their
  minuteness, but the whole lung appears full of blood. The
  canals from the vein lie above the tubes given off from
  the windpipe.”

The key to the whole of the foregoing description of the heart lies
in the passages (_G_) and (_L_). They prove that Aristotle, like
Galen, five hundred years afterwards, and like the great majority
of the old Greek anatomists, did not reckon what we call the right
auricle as a constituent of the heart at all, but as a hollow part, or
dilatation, of the “great vein.” Aristotle is careful to state that his
observations were conducted on suffocated animals; and if any one will
lay open the thorax of a dog or a rabbit, which has been killed with
chloroform, in such a manner as to avoid wounding any important vessel,
he will at once see why Aristotle adopted this view.

For, as the subjoined figure (p. 185) shows, the vena cava inferior
(_b_), the right auricle (_R.a._), and the vena cava superior and
innominate vein (_V.I._) distended with blood seem to form one
continuous column, to which the heart is attached as a sort of
appendage. This column is, as Aristotle says, vein above (_a_) and vein
below (_b_), the upper and the lower divisions being connected διὰ
τοῦ κοίλου τοῦ μέσου—or by means of the intervening cavity or chamber
(_R.a._)—which is that which we call the right auricle.

[Illustration:

  A dog having been killed by chloroform, enough of the
  right wall of the thorax was removed, without any notable
  bleeding, to expose the thoracic viscera. A carefully
  measured outline sketch of the parts _in situ_ was then
  made, and on dissection, twenty-four hours afterwards,
  the necessary anatomical details were added. The woodcut
  is a faithfully reduced copy of the drawing thus
  constructed; and it represents the relations of the heart
  and great vessels as Aristotle saw them in a suffocated
  animal.

  All but the inner lobe of the right lung has been
  removed; as well as the right half of the pericardium and
  the right walls of the right auricle and ventricle. It
  must be remembered that the thin transparent pericardial
  membrane appears nothing like so distinct in nature.

  _a.b._, Aristotle’s “great vein”; _V.I._, right vena
  innominata and vena cava superior; _b_, the inferior
  vena cava; _R.a._, the “hollow middle” part of the great
  vein or the right auricle; _R.v′_, the prolongation of
  the cavity of the right ventricle _R.v_ towards the
  pulmonary artery; _tr_, one of the tricuspid valves;
  _Pc_, the pericardium; _I.sv_, superior intercostal
  vein; _Az_, vena azygos; _P.A._, right pulmonary artery;
  _Br_, right bronchus; _L_, inner lobe of the right lung;
  _Œ_, œsophagus; _Ao_, descending aorta; _H_, liver, in
  section, with hepatic vein, vena portæ, and gall-bladder,
  _gb_, separated by the diaphragm, also seen in section,
  from the thoracic cavity.]

But when, from the four cavities of the heart recognised by us moderns,
one is excluded, there remain three—which is just what Aristotle says.
The solution of the difficulty is, in fact, as absurdly simple as that
presented by the egg of Columbus; and any error there may be, is not
to be put down to Aristotle, but to that inability to comprehend that
the same fact may be accurately described in different ways, which
is the special characteristic of the commentatorial mind. That the
three cavities mentioned by Aristotle are just those which remain if
the right auricle is omitted, is plain enough from what is said in
(_B_), (_C_), (_E_), (_I_), and (_L_). For, in a suffocated animal,
the “right cavity” which is directly connected with the great vein,
and is obviously the right ventricle, being distended with blood, will
look much larger than the middle cavity, which, since it gives rise
to the aorta, can only be the left ventricle. And this, again, will
appear larger than the thin and collapsed left auricle, which must
be Aristotle’s left cavity, inasmuch as this cavity is said to be
connected by πόροι with the lung. The reason why Aristotle considered
the left auricle to be a part of the heart, while he merged the right
auricle in the great vein, is, obviously, the small relative size of
the venous trunks and their sharper demarcation from the auricle.
Galen, however, perhaps more consistently, regarded the left auricle
also as a mere part of the “arteria venosa.” The canal which leads
from the right cavity of the heart to the lung (or, as Aristotle
puts it (_E_), from the lung to the heart) is, without doubt, the
pulmonary artery. But it may be said that, in this case, Aristotle
contradicts himself, inasmuch as in (_P_) and (_Q_) a vessel, which
is obviously the pulmonary artery, is described as a branch of the
great vein. However, this difficulty also disappears, if we reflect
that, in Aristotle’s way of looking at the matter, the line of
demarcation between the great vein and the heart coincides with the
right auriculo-ventricular aperture; and that, inasmuch as the conical
prolongation of the right ventricle which leads to the pulmonary
artery (_R.v′_ in the Figure), lies close in front of the auricle,
its base may very easily (as the figure shows) be regarded as part of
the general opening of the great vein into the right ventricle. In
fact, it is clear that Aristotle, having failed to notice the valves
of the heart, did not distinguish the part of the right ventricle
from which the pulmonary artery arises (_R.v′_) from the proper trunk
of the artery on the one hand, and from the right auricle (_R.a_) on
the other. Thus the root, as we may call it, of the pulmonary artery
and the right auricle, taken together, are spoken of as the “part of
the great vein which extends upwards” (_P_); and, as the vena azygos
(_Az_) was one branch of this, so the “vein to the lung” was regarded
as another branch of it. But the latter branch, being given off close
to the connection of the great vein with the ventricle, was also
counted as one of the two πόροι by which the “heart” (that is to say
the right ventricle, the left ventricle, and the left auricle of our
nomenclature) communicates with the lung.

The only other difficulty that I observe is connected with (_K_). If
Aristotle intended by this to affirm that the middle cavity (the left
ventricle), like the other two, is directly connected with the lung by
a πόρος, he would be in error. But he has excluded this interpretation
of his words by (_E_), in which the number and relations of the
canals, the existence of which he admits, are distinctly defined. I
can only imagine then, that, so far as this passage applies to the
left ventricle, it merely refers to the indirect communication of that
cavity with the vessels of the lungs, through the left auricle.

On this evidence I submit that there is no escape from the conclusion
that, instead of having committed a gross blunder, Aristotle has given
a description of the heart which, so far as it goes, is remarkably
accurate. He is in error only in regard to the differences which he
imagines to exist between large and small hearts (_H_).

Cuvier (who has been followed by other commentators) ascribes another
error to Aristotle:—

  “Aristote suppose que la trachée-artère se prolonge
  jusqu’au cœur, et semble croire, en conséquence, que
  l’air y pénétre (_l. c._ p. 152).”

Upon what foundation Cuvier rested the first of these two assertions,
I am at a loss to divine. As a matter of fact, it will appear from the
following excerpts that Aristotle gives an account of the structure of
the lungs which is almost as good as that of the heart, and that it
contains nothing about any prolongation of the windpipe to the heart.

  “Within the neck lie what is called the œsophagus (so
  named on account of its length and its narrowness) and
  the windpipe (ἀρτηρία). The position of the windpipe in
  all animals that have one, is in front of the œsophagus.
  All animals which possess a lung have a windpipe. The
  windpipe is of a cartilaginous nature and is exsanguine,
  but is surrounded by many little veins....

  “It goes downwards towards the middle of the lung, and
  then divides for each of the halves of the lung. In all
  animals that possess one, the lung is divided into two
  parts; but, in those which bring forth their young alive,
  the separation is not equally well marked, least of all
  in man.

  “In oviparous animals, such as birds, and in quadrupeds
  which are oviparous, the one half of the lung is widely
  separated from the other; so that it appears as if they
  had two lungs. And from being single, the windpipe
  becomes (divided into) two, which extend to each half of
  the lung. It is fastened to the great vein, and to what
  is called the aorta. When the windpipe is blown up, the
  air passes into the hollow parts of the lung. In these,
  are cartilaginous tubes (διαφύσεις) which unite at an
  angle; from the tubes passages (τρήματα) traverse the
  whole of the lung; they are continually given off, the
  smaller from the larger.” (Book i. 16.)

That Aristotle should speak of the lung as a single organ divided into
two halves, and should say that the division is least marked in man,
is puzzling at first; but the statement becomes intelligible, if we
reflect upon the close union of the bronchi, the pulmonary vessels and
the mediastinal walls of the pleuræ, in mammals;[38] and it is quite
true that the lungs are much more obviously distinct from one another
in birds.

Aubert and Wimmer translate the last paragraph of the passage just
cited as follows:—

  “Diese haben aber knorpelige Scheidewände, welche unter
  spitzen Winkeln zusammentreten, und aus ihnen führen
  Oeffnungen durch die ganze Lunge, indem sie sich in immer
  kleineren verzweigen.”

But I cannot think that by διαφύσεις and τρήματα, in this passage,
Aristotle meant either “partitions” or openings in the ordinary
sense of the latter word. For, in Book iii. Cap. 3, in describing
the distribution of the “vein which goes to the lung” (the pulmonary
artery), he says that it

  “extends alongside each tube (σύριγγα) and each passage
  (τρῆμα), the larger beside the larger, and the smaller
  beside the smaller; so that no part (of the lung) can be
  found from which a passage (τρῆμα) and a vein are absent.”

Moreover, in Book i. 17, he says—

  “Canals (πόροι) from the heart pass to the lung and
  divide in the same fashion as the windpipe does, closely
  accompanying those from the windpipe through the whole
  lung.”

And again in Book i. 17—

  “It (the lung) is entirely spongy, and alongside of each
  tube (σύριγγα) run canals (πόροι) from the great vein.”

On comparing the last three statements with the facts of the case, it
is plain that by σύριγγες, or tubes, Aristotle means the bronchi and so
many of their larger divisions as obviously contain cartilages; and
that by διαφύσεις χονδρώδεις he denotes the same things; and, if this
be so, then the τρήματα must be the smaller bronchial canals, in which
the cartilages disappear.

This view of the structure of the lung is perfectly correct so far
as it extends; and, bearing it in mind, we shall be in a position to
understand what Aristotle thought about the passage of air from the
lungs into the heart. In every part of the lung, he says, in effect,
there is an air tube which is derived from the trachea, and other tubes
which are derived from the πόροι which connect the lung with the heart
(_suprà_, _C_). Their applied walls constitute the thin “synapses” (τὴν
σύναψιν) through which the air passes out of the air tubes into the
πόροι, or blood-vessels, by transudation or diffusion; for there is no
community between the cavities of the air tubes and cavities of the
canals; that is to say, no opening from one into the other (_suprà_,
_D_).

On the words “κοινὸς πόρος” Aubert and Wimmer remark (_l. c._ p. 239),
“Da A. die Ansicht hat die Lungenluft würde dem Herzen zugeführt,
so postulirt er statt vieler kleiner Verbindungen einen grossen
Verbindungsgang zwischen Lunge und Herz.”

But does Aristotle make this assumption? The only evidence so far as
I know in favour of the affirmative answer to this question is the
following passage:—

  “Συνήρτεται δὲ καὶ ἡ καρδία τῇ ἀρτηριᾷ πιμελώδεσι
  καὶ χονδρώδεσι καὶ ἰνώδεσι δεσμοῖς· ᾗ δὲ συνήρτεται,
  κοῖλόν ἐστιν. φυσωμένης δὲ τῆς ἀρτηρίας μὲν ἐνίοις ἐν οὐ
  κατάδηλον ποιεῖ, ἐν δὲ τοῖς μείζοσι τῶν ζῴων δῆλον ὅτι
  εἰσέρχεται τὸ πνεῦμα εἰς αὐτὴν” (i. cap. 16).

  “The heart and the windpipe are connected by fatty and
  cartilaginous and fibrous bands; where they are connected
  it is hollow. Blowing into the windpipe does not show
  clearly in some animals, but in the larger animals it is
  clear that the air goes into it.”

Aubert and Wimmer give a somewhat different rendering of this passage:—

  “Auch das Herz hängt mit der Luftröhre durch fettreiche,
  knorpelige und faserige Bänder zusammen; und da, wo sie
  zusammenhängen, ist eine Höhlung. Beim Aufblasen der
  Lunge wird es bei manchen Thieren nicht wahrnehmbar, bei
  den grösseren aber ist es offenbar, dass die Luft in das
  Herz gelangt.”

The sense here turns upon the signification which is to be ascribed to
εἰς αὐτὴν. But if these words refer to the heart, then Aristotle has
distinctly pointed out the road which the air, in his opinion, takes,
namely, through the “synapses” (_D_); and there is no reason that I
can discover to believe that he “postulated” any other and more direct
communication.

With respect to the meaning of κοῖλόν ἐστιν, Aubert and Wimmer observe:—

  “Dies scheint wohl die kurze Lungenvene zu sein.
  Schneider bezieht dies auf die Vorkammern, allein diese
  werden unten als Höhlen des Herzens beschrieben.”

I am disposed to think, on the contrary, that the words refer simply
to the cavity of the pericardium. For a part of this cavity (_sinus
transversus pericardii_) lies between the aorta, on the one hand, and
the pulmonary vessels with the bifurcation of the trachea, on the other
hand, and is much more conspicuous in some animals than in man. It is
strictly correct, therefore, in Aristotle’s words, to say that where
the heart and the windpipe are connected “it is hollow.” If he had
meant to speak of one of the pulmonary veins, or of any of the cavities
of the heart, he would have used the terms πόροι or κοιλίας which he
always employs for these parts.

According to Aristotle, then, the air taken into the lungs passes, from
the final ramifications of the bronchial tubes into the corresponding
branches of the pulmonary blood-vessels, not through openings, but by
transudation, or, as we should nowadays say, diffusion, through the
thin partitions formed by the applied coats of the two sets of canals.
But the “pneuma” which thus reached the interior of the blood-vessels
was not, in Aristotle’s opinion, exactly the same thing as the air.
It was “ἀὴρ πολὺς ῥέων καὶ ἀθρόος” (“De Mundo,” iv. 9)—subtilised and
condensed air; and it is hard to make out whether Aristotle considered
it to possess the physical properties of an elastic fluid or those of
a liquid. As he affirms that all the cavities of the heart contain
blood (_F_), it is clear that he did not hold the erroneous view
propounded in the next generation by Erasistratus. On the other hand,
the fact that he supposes that the spermatic arteries do not contain
blood but only an αἱματῶδης ὑγρόν (“Hist. Animalium,” iii. 1), shows
that his notions respecting the contents of the arteries were vague.
Nor does he seem to have known that the pulse is characteristic only
of the arteries; and as he thought that the arteries end in solid
fibrous bands, he naturally could not have entertained the faintest
conception of the true motion of the blood. But, without attempting
to read into Aristotle modern conceptions which never entered his
mind, it is only just to observe that his view of what becomes of the
air taken into the lungs is by no means worthy of contempt as a gross
error. On the contrary, here, as in the case of his anatomy of the
heart, what Aristotle asserts is true as far as it goes. Something
does actually pass from the air contained in the lungs through the
coats of the vessels into the blood, and thence to the heart; to wit,
oxygen. And I think that it speaks very well for ancient Greek science
that the investigator of so difficult a physiological problem as that
of respiration, should have arrived at a conclusion, the statement of
which, after the lapse of more than two thousand years, can be accepted
as a thoroughly established scientific truth.

I trust that the case in favour of removing the statements about
the heart, from the list of the “errors of Aristotle” is now clear;
and that the evidence proves, on the contrary, that they justify
us in forming a very favourable estimate of the oldest anatomical
investigations among the Greeks of which any sufficient record remains.

But is Aristotle to be credited with the merit of having ascertained so
much of the truth? This question will not appear superfluous to those
who are acquainted with the extraordinary history of Aristotle’s works,
or who adopt the conclusion of Aubert and Wimmer, that, of the ten
books of the “Historia Animalium” which have come down to us, three
are largely or entirely spurious, and that the others contain many
interpolations by later writers.

It so happens, however, that, apart from other reasons, there are
satisfactory internal grounds for ascribing the account of the heart
to a writer of the time at which Aristotle lived. For, within thirty
years of his death, the anatomists of the Alexandrian school had
thoroughly investigated the structure and the functions of the valves
of the heart. During this time, the manuscripts of Aristotle were in
the possession of Theophrastus; and no interpolator of later date would
have shown that he was ignorant of the nature and significance of
these important structures, by the brief and obscure allusion—“in its
cavities there are tendons” (_A_). On the other hand, Polybus, whose
account of the vascular system is quoted in the “Historia Animalium”
was an elder contemporary of Aristotle. Hence, if any part of the
work faithfully represents that which Aristotle taught, we may safely
conclude that the description of the heart does so. Having granted
this much, however, it is another question, whether Aristotle is to
be regarded as the first discoverer of the facts which he has so well
stated, or whether he, like other men, was the intellectual child of
his time and simply carried on a step or two the work which had been
commenced by others.

On the subject of Aristotle’s significance as an original worker in
biology extraordinarily divergent views have been put forward. If we
are to adopt Cuvier’s estimate, Aristotle was simply a miracle:—

  “Avant Aristote la philosophie, entièrement spéculative,
  se perdait dans les abstractions dépourvues de fondement;
  la science n’existait pas. Il semble qu’elle soit
  sortie toute faite du cerveau d’Aristote comme Minerve,
  toute armée, du cerveau de Jupiter. Seul, en effet,
  sans antécédents, sans rien emprunter aux siècles qui
  l’avaient précédé, puisqu’ils n’avaient rien produit de
  solide, le disciple de Platon découvrit et démontra plus
  de vérités, executa plus de travaux scientifiques en un
  vie de soixante-deux ans, qu’après lui vingt siècles n’en
  ont pu faire,”[39] etc. etc.

  “Aristote est le premier qui ait introduit la méthode
  de l’induction, de la comparaison des observations
  pour en faire sortir des idées générales, et celle de
  l’expérience pour multiplier les faits dont ces idées
  générales peuvent être déduites.”—ii. p. 515.

The late Mr. G. H. Lewes,[40] on the contrary, tells us “on a
superficial examination, therefore, he [Aristotle] will seem to have
given tolerable descriptions; especially if approached with that
disposition to discover marvels which unconsciously determines us
in our study of eminent writers. But a more unbiassed and impartial
criticism will disclose that he has given no single anatomical
description of the least value. All that he knew may have been known,
and probably was known, without dissection.... I do not assert that
he never opened an animal; on the contrary it seems highly probable
that he had opened many.... He never followed the course of a vessel
or a nerve; never laid bare the origin and insertion of a muscle;
never discriminated the component parts of organs; never made clear to
himself the connection of organs into systems.”—(pp. 156-7.)

In the face of the description of the heart and lungs, just quoted,
I think we may venture to say that no one who has acquired even an
elementary practical acquaintance with anatomy, and knows of his own
knowledge that which Aristotle describes, will agree with the opinion
expressed by Mr. Lewes; and those who turn to the accounts of the
structure of the rock lobster and the common lobster, or to that of the
Cephalopods and other Mollusks, in the fourth book of the “Historia
Animalium” will probably feel inclined to object to it still more
strongly.

On the other hand, Cuvier’s exaggerated panegyric will as little bear
the test of cool discussion. In Greece, the century before Aristotle’s
birth was a period of great intellectual activity, in the field of
physical science no less than elsewhere. The method of induction has
never been used to better effect than by Hippocrates; and the labours
of such men as Alkmeon, Demokritus, and Polybus, among Aristotle’s
predecessors; Diokles, and Praxagoras, among his contemporaries, laid a
solid foundation for the scientific study of anatomy and development,
independently of his labours. Aristotle himself informs us that the
dissection of animals was commonly practised; that the aorta had been
distinguished from the great vein; and that the connection of both with
the heart had been observed by his predecessors. What they thought
about the structure of the heart itself or that of the lungs, he does
not tell us, and we have no means of knowing. So far from arrogantly
suggesting that he owed nothing to his predecessors, Aristotle is
careful to refer to their observations, and to explain why, in his
judgment, they fell into the errors which he corrects.

Aristotle’s knowledge, in fact, appears to have stood in the same
relation to that of such men as Polybus and Diogenes of Apollonia, as
that of Herophilus and Erasistratus did to his own, so far as the heart
is concerned. He carried science a step beyond the point at which he
found it; a meritorious, but not a miraculous, achievement. What he
did, required the possession of very good powers of observation; if
they had been powers of the highest class, he could hardly have left
such conspicuous objects as the valves of the heart to be discovered by
his successors.

And this leads me to make a final remark upon a singular feature of
the “Historia Animalium.” As a whole, it is a most notable production,
full of accurate information, and of extremely acute generalisations of
the observations accumulated by naturalists up to that time. And yet,
every here and there, one stumbles upon assertions respecting matters
which lie within the scope of the commonest inspection, which are not
so much to be called errors, as stupidities. What is to be made of the
statement that the sutures of women’s skulls are different from those
of men; that men and sundry male animals have more teeth than their
respective females; that the back of the skull is empty; and so on? It
is simply incredible to me, that the Aristotle who wrote the account of
the heart, also committed himself to absurdities which can be excused
by no theoretical prepossession and which are contradicted by the
plainest observation.

What, after all, were the original manuscripts of the “Historia
Animalium”? If they were notes of Aristotle’s lectures taken by some of
his students, any lecturer who has chanced to look through such notes,
would find the interspersion of a foundation of general and sometimes
minute accuracy, with patches of transcendent blundering, perfectly
intelligible. Some competent Greek scholar may perhaps think it worth
while to tell us what may be said for or against the hypothesis thus
hinted. One obvious difficulty in the way of adopting it is the fact
that, in other works, Aristotle refers to the “Historia Animalium” as
if it had already been made public by himself.




IX.

ON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS HISTORY.


The first half of the seventeenth century is one of the great epochs
of biological science. For though suggestions and indications of the
conceptions which took definite shape, at that time, are to be met
with in works of earlier date, they are little more than the shadows
which coming truth casts forward; men’s knowledge was neither extensive
enough, nor exact enough, to show them the solid body of fact which
threw these shadows.

But, in the seventeenth century, the idea that the physical processes
of life are capable of being explained in the same way as other
physical phenomena, and, therefore, that the living body is a
mechanism, was proved to be true for certain classes of vital actions;
and, having thus taken firm root in irrefragable fact, this conception
has not only successfully repelled every assault which has been made
upon it, but has steadily grown in force and extent of application,
until it is now the expressed or implied fundamental proposition of the
whole doctrine of scientific Physiology.

If we ask to whom mankind are indebted for this great service, the
general voice will name William Harvey. For, by his discovery of the
circulation of the blood in the higher animals, by his explanation of
the nature of the mechanism by which that circulation is effected,
and by his no less remarkable, though less known, investigations of
the process of development, Harvey solidly laid the foundations of
all those physical explanations of the functions of sustentation and
reproduction which modern physiologists have achieved.

But the living body is not only sustained and reproduced: it adjusts
itself to external and internal changes; it moves and feels. The
attempt to reduce the endless complexities of animal motion and
feeling to law and order is, at least, as important a part of the task
of the physiologist as the elucidation of what are sometimes called
the vegetative processes. Harvey did not make this attempt himself;
but the influence of his work upon the man who did make it is patent
and unquestionable. This man was René Descartes, who, though by many
years Harvey’s junior, died before him; and yet, in his short span
of fifty-four years, took an undisputed place, not only among the
chiefs of philosophy, but amongst the greatest and most original of
mathematicians; while, in my belief, he is no less certainly entitled
to the rank of a great and original physiologist; inasmuch as he did
for the physiology of motion and sensation that which Harvey had done
for the circulation of the blood, and opened up that road to the
mechanical theory of these processes, which has been followed by all
his successors.

Descartes was no mere speculator, as some would have us believe: but a
man who knew of his own knowledge what was to be known of the facts of
anatomy and physiology in his day. He was an unwearied dissector and
observer; and it is said, that, on a visitor once asking to see his
library, Descartes led him into a room set aside for dissections, and
full of specimens under examination. “There,” said he, “is my library.”

I anticipate a smile of incredulity when I thus champion Descartes’
claim to be considered a physiologist of the first rank. I expect to
be told that I have read into his works what I find there, and to be
asked, Why is it that we are left to discover Descartes’ deserts at
this time of day, more than two centuries after his death? How is it
that Descartes is utterly ignored in some of the latest works which
treat expressly of the subject in which he is said to have been so
great?

It is much easier to ask such questions than to answer them, especially
if one desires to be on good terms with one’s contemporaries; but, if I
must give an answer, it is this: The growth of physical science is now
so prodigiously rapid, that those who are actively engaged in keeping
up with the present, have much ado to find time to look at the past,
and even grow into the habit of neglecting it. But, natural as this
result may be, it is none the less detrimental. The intellect loses,
for there is assuredly no more effectual method of clearing up one’s
own mind on any subject than by talking it over, so to speak, with
men of real power and grasp, who have considered it from a totally
different point of view. The parallax of time helps us to the true
position of a conception, as the parallax of space helps us to that of
a star. And the moral nature loses no less. It is well to turn aside
from the fretful stir of the present and to dwell with gratitude and
respect upon the services of those “mighty men of old who have gone
down to the grave with their weapons of war,” but who, while they yet
lived, won splendid victories over ignorance. It is well, again, to
reflect that the fame of Descartes filled all Europe, and his authority
overshadowed it, for a century; while now, most of those who know his
name think of him, either as a person who had some preposterous notions
about vortices and was deservedly annihilated by the great Sir Isaac
Newton; or as the apostle of an essentially vicious method of deductive
speculation; and that, nevertheless, neither the chatter of shifting
opinion, nor the silence of personal oblivion, has in the slightest
degree affected the growth of the great ideas of which he was the
instrument and the mouthpiece.

It is a matter of fact that the greatest physiologist of the eighteenth
century, Haller, in treating of the functions of nerve, does little
more than reproduce and enlarge upon the ideas of Descartes. It is a
matter of fact that David Hartley, in his remarkable work the “Essay
on Man,” expressly, though still insufficiently, acknowledges the
resemblance of his fundamental conceptions to those of Descartes; and
I shall now endeavour to show that a series of propositions, which
constitute the foundation and essence of the modern physiology of the
nervous system, are fully expressed and illustrated in the works of
Descartes.

  I. _The brain is the organ of sensation, thought, and
  emotion; that is to say, some change in the condition of
  the matter of this organ is the invariable antecedent of
  the state of consciousness to which each of these terms
  is applied._

In the “Principes de la Philosophie” (§ 169), Descartes says:—[41]

  “Although the soul is united to the whole body, its
  principal functions are, nevertheless, performed in
  the brain; it is here that it not only understands and
  imagines, but also feels; and this is effected by the
  intermediation of the nerves, which extend in the form
  of delicate threads from the brain to all parts of the
  body, to which they are attached in such a manner, that
  we can hardly touch any part of the body without setting
  the extremity of some nerve in motion. This motion passes
  along the nerve to that part of the brain which is the
  common sensorium, as I have sufficiently explained in
  my Treatise on Dioptrics; and the movements which thus
  travel along the nerves, as far as that part of the
  brain with which the soul is closely joined and united,
  cause it, by reason of their diverse characters, to have
  different thoughts. And it is these different thoughts of
  the soul, which arise immediately from the movements that
  are excited by the nerves in the brain, which we properly
  term our feelings, or the perceptions of our senses.”

Elsewhere,[42] Descartes, in arguing that the seat of the passions is
not (as many suppose) the heart, but the brain, uses the following
remarkable language:—

  “The opinion of those who think that the soul receives
  its passions in the heart, is of no weight, for it is
  based upon the fact that the passions cause a change to
  be felt in that organ; and it is easy to see that this
  change is felt, as if it were in the heart, only by the
  intermediation of a little nerve which descends from the
  brain to it; Just as pain is felt, as if it were in the
  foot, by the intermediation of the nerves of the foot;
  and the stars are perceived, as if they were in the
  heavens, by the intermediation of their light and of the
  optic nerves. So that it is no more necessary for the
  soul to exert its functions immediately in the heart, to
  feel its passions there, than it is necessary that it
  should be in the heavens to see the stars there.”

This definite allocation of all the phenomena of consciousness to the
brain as their organ, was a step the value of which it is difficult
for us to appraise, so completely has Descartes’ view incorporated
itself with every-day thought and common language. A lunatic is said
to be “crack-brained” or “touched in the head,” a confused thinker
is “muddle-headed,” while a clever man is said to have “plenty of
brains;” but it must be remembered that at the end of the last century
a considerable, though much over-estimated, anatomist, Bichat, so far
from having reached the level of Descartes, could gravely argue that
the apparatuses of organic life are the sole seat of the passions,
which in no way affect the brain, except so far as it is the agent by
which the influence of the passions is transmitted to the muscles.[43]

Modern physiology, aided by pathology, easily demonstrates that the
brain is the seat of all forms of consciousness, and fully bears out
Descartes’ explanation of the reference of those sensations in the
viscera which accompany intense emotion, to these organs. It proves,
directly, that those states of consciousness which we call sensations
are the immediate consequent of a change in the brain excited by
the sensory nerves; and, on the well-known effects of injuries, of
stimulants, and of narcotics, it bases the conclusion that thought and
emotion are, in like manner, the consequents of physical antecedents.

  II. _The movements of animals are due to the change of
  form of muscles, which shorten and become thicker; and
  this change of form in a muscle arises from a motion of
  the substance contained within the nerves which go to the
  muscle_.

In the “Passions de l’Âme,” Art. vii., Descartes writes:—

  “Moreover, we know that all the movements of the limbs
  depend on the muscles, and that these muscles are opposed
  to one another in such a manner, that when one of them
  shortens, it draws along the part of the body to which
  it is attached, and so gives rise to a simultaneous
  elongation of the muscle which is opposed to it. Then,
  if it happens, afterwards, that the latter shortens, it
  causes the former to elongate, and draws towards itself
  the part to which it is attached. Lastly, we know that
  all these movements of the muscles, as all the senses,
  depend on the nerves, which are like little threads or
  tubes, which all come from the brain, and, like it,
  contain a certain very subtle air or wind, termed the
  animal spirits.”

The property of muscle mentioned by Descartes now goes by the general
name of contractility, but his definition of it remains untouched. The
long-continued controversy whether contractile substance, speaking
generally, has an inherent power of contraction, or whether it
contracts only in virtue of an influence exerted by nerve, is now
settled in Haller’s favour; but Descartes’ statement of the dependence
of muscular contraction on nerve holds good for the higher forms of
muscle, under normal circumstances; so that, although the structure of
the various modifications of contractile matter has been worked out
with astonishing minuteness—although the delicate physical and chemical
changes which accompany muscular contraction have been determined to
an extent of which Descartes could not have dreamed, and have quite
upset his hypothesis that the cause of the shortening and thickening of
the muscle is the flow of animal spirits into it from the nerves—the
important and fundamental part of his statement remains perfectly true.

The like may be affirmed of what he says about nerve. We know now that
nerves are not exactly tubes, and that “animal spirits” are myths; but
the exquisitely refined methods of investigation of Dubois-Reymond and
of Helmholz have no less clearly proved that the antecedent of ordinary
muscular contraction is a motion of the molecules of the nerve going to
the muscle; and that this motion is propagated with a measurable, and
by no means great, velocity, through the substance of the nerve towards
the muscle.

With the progress of research, the term “animal spirits” gave way to
“nervous fluid,” and “nervous fluid” has now given way to “molecular
motion of nerve-substance.” Our conceptions of what takes place in
nerve have altered in the same way as our conceptions of what takes
place in a conducting wire have altered, since electricity was shown to
be not a fluid, but a mode of molecular motion. The change is of vast
importance, but it does not affect Descartes’ fundamental idea, that a
change in the substance of a motor nerve propagated towards a muscle is
the ordinary cause of muscular contraction.

  III. _The sensations of animals are due to a motion of
  the substance of the nerves which connect the sensory
  organs with the brain._

In _La Dioptrique_ (Discours Quatrième), Descartes explains, more fully
than in the passage cited above, his hypothesis of the mode of action
of sensory nerves:—

  “It is the little threads of which the inner substance
  of the nerves is composed which subserve sensation. You
  must conceive that these little threads, being inclosed
  in tubes, which are always distended and kept open by
  the animal spirits which they contain, neither press
  upon nor interfere with one another, and are extended
  from the brain to the extremities of all the members
  which are sensitive—in such a manner, that the slightest
  touch which excites the part of one of the members to
  which a thread is attached, gives rise to a motion of
  the part of the brain whence it arises, just as by
  pulling one of the ends of a stretched cord, the other
  end is instantaneously moved.... And we must take care
  not to imagine that, in order to feel, the soul needs
  to behold certain images sent by the objects of sense
  to the brain, as our philosophers commonly suppose;
  or, at least, we must conceive these images to be
  something quite different from what they suppose them
  to be. For, as all they suppose is that these images
  ought to resemble the objects which they represent, it
  is impossible for them to show how they can be formed by
  the objects received by the organs of the external senses
  and transmitted to the brain. And they have had no reason
  for supposing the existence of these images except this;
  seeing that the mind is readily excited by a picture to
  conceive the object which is depicted, they have thought
  that it must be excited in the same way to conceive those
  objects which affect our senses by little pictures of
  them formed in the head; instead of which we ought to
  recollect that there are many things besides images which
  may excite the mind, as, for example, signs and words,
  which have not the least resemblance to the objects which
  they signify.”[44]

Modern physiology amends Descartes’ conception of the mode of action of
sensory nerves in detail, by showing that their structure is the same
as that of motor nerves; and that the changes which take place in them,
when the sensory organs with which they are connected are excited, are
of just the same nature as those which occur in motor nerves, when the
muscles to which they are distributed are made to contract: there is a
molecular change which, in the case of the sensory nerve, is propagated
towards the brain. But the great fact insisted upon by Descartes, that
no likeness of external things is, or can be, transmitted to the mind
by the sensory organs; on the contrary, that, between the external
cause of a sensation and the sensation, there is interposed a mode
of motion of nervous matter, of which the state of consciousness is
no likeness, but a mere symbol, is of the profoundest importance. It
is the physiological foundation of the doctrine of the relativity
of knowledge, and a more or less complete idealism is a necessary
consequence of it.

For of two alternatives one must be true. Either consciousness is
the function of a something distinct from the brain, which we call
the soul, and a sensation is the mode in which this soul is affected
by the motion of a part of the brain; or there is no soul, and a
sensation is something generated by the mode of motion of a part of
the brain. In the former case, the phenomena of the senses are purely
spiritual affections; in the latter, they are something manufactured
by the mechanism of the body, and as unlike the causes which set that
mechanism in motion, as the sound of a repeater is unlike the pushing
of the spring which gives rise to it.

The nervous system stands between consciousness and the assumed
external world, as an interpreter who can talk with his fingers stands
between a hidden speaker and a man who is stone deaf—and Realism is
equivalent to a belief on the part of the deaf man, that the speaker
must also be talking with his fingers. “Les extrêmes se touchent;” the
shibboleth of materialists that “thought is a secretion of the brain,”
is the Fichtean doctrine that “the phenomenal universe is the creation
of the Ego,” expressed in other language.

  IV. _The motion of the matter of a sensory nerve may
  be transmitted through the brain to motor nerves, and
  thereby give rise to contraction of the muscles to which
  these motor nerves are distributed; and this reflection
  of motion from a sensory into a motor nerve may take
  place without volition, or even contrary to it._

In stating these important truths, Descartes defined that which we now
term “reflex action.” Indeed he almost uses the term itself, as he
talks of the “animal spirits” as “réfléchis,”[45] from the sensory into
the motor nerves. And that this use of the word “reflected” was no mere
accident, but that the importance and appropriateness of the idea it
suggests was fully understood by Descartes’ contemporaries, is apparent
from a passage in Willis’s well-known essay, “De Animâ Brutorum,”
published in 1672, in which, in giving an account of Descartes’ views,
he speaks of the animal spirits being diverted into motor channels,
“velut undulatione reflexâ.”[46]

Nothing can be clearer in statement, or in illustration, than the view
of reflex action which Descartes gives in the “Passions de l’Âme,” Art.
xiii.

After recapitulating the manner in which sensory impressions
transmitted by the sensory nerves to the brain give rise to sensation,
he proceeds:—

  “And in addition to the different feelings excited in the
  soul by these different motions of the brain, the animal
  spirits, without the intervention of the soul, may take
  their course towards certain muscles, rather than towards
  others, and thus move the limbs, as I shall prove by
  an example. If some one moves his hand rapidly towards
  our eyes, as if he were going to strike us, although
  we know that he is a friend, that he does it only in
  jest, and that he will be very careful to do us no harm,
  nevertheless it will be hard to keep from winking. And
  this shows, that it is not by the agency of the soul
  that the eyes shut, since this action is contrary to
  that volition which is the only, or at least the chief,
  function of the soul; but it is because the mechanism
  of our body is so disposed, that the motion of the hand
  towards our eyes excites another movement in our brain,
  and this sends the animal spirits into those muscles
  which cause the eyelids to close.”

Since Descartes’ time, experiment has eminently enlarged our knowledge
of the details of reflex action. The discovery of Bell has enabled us
to follow the tracks of the sensory and motor impulses, along distinct
bundles of nerve fibres; and the spinal cord, apart from the brain, has
been proved to be a great centre of reflex action; but the fundamental
conception remains as Descartes left it, and it is one of the pillars
of nerve physiology at the present day.

  V. _The motion of any given portion of the matter of the
  brain excited by the motion of a sensory nerve, leaves
  behind a readiness to be moved in the same way, in that
  part. Anything which resuscitates the motion gives
  rise to the appropriate feeling. This is the physical
  mechanism of memory_.

Descartes imagined that the pineal body (a curious appendage to the
upper side of the brain, the function of which, if it have any, is
wholly unknown) was the instrument through which the soul received
impressions from, and communicated them to, the brain. And he thus
endeavours to explain what happens when one tries to recollect
something:—

  “Thus when the soul wills to remember anything, this
  volition, causing the [pineal] gland to incline itself
  in different directions, drives the [animal] spirits
  towards different regions of the brain, until they reach
  that part in which are the traces, which the object
  which it desires to remember has left. These traces are
  produced thus: those pores of the brain through which the
  [animal] spirits have previously been driven, by reason
  of the presence of the object, have thereby acquired a
  tendency to be opened by the animal spirits which return
  towards them, more easily than other pores, so that the
  animal spirits, impinging on these pores, enter them
  more readily than others. By this means they excite a
  particular movement in the pineal gland, which represents
  the object to the soul, and causes it to know what it is
  which it desired to recollect.”[47]

That memory is dependent upon some condition of the brain is a fact
established by many considerations—among the most important of which
are the remarkable phenomena of aphasia. And that the condition of the
brain on which memory depends, is largely determined by the repeated
occurrence of that condition of its molecules, which gives rise to the
idea of the thing remembered, is no less certain.
Every boy who learns his lesson by repeating it exemplifies the fact.
Descartes, as we have seen, supposes that the pores of a given part
of the brain are stretched by the animal spirits, on the occurrence
of a sensation, and that the part of the brain thus stretched, being
imperfectly elastic, does not return to exactly its previous condition,
but remains more distensible than it was before. Hartley supposes
that the vibrations, excited by a sensory, or other, impression,
do not die away, but are represented by smaller vibrations or
“vibratiuncules,” the permanency and intensity of which are in relation
with the frequency of repetition of the primary vibrations. Haller has
substantially the same idea, but contents himself with the general term
“mutationes,” to express the cerebral change which is the cause of a
state of consciousness. These “mutationes” persist for a long time
after the cause which gives rise to them has ceased to operate, and
are arranged in the brain according to the order of coexistence and
succession of their causes. And he gives these persistent “mutationes”
the picturesque name of _vestigia rerum_, “quæ non in mente sed in ipso
corpore et in medulla quidem cerebri ineffabili modo incredibiliter
minutis notis et copia infinita, inscriptæ sunt.”[48] I do not know
that any modern theory of the physical conditions of memory differs
essentially from these, which are all children—_mutatis mutandis_—of
the Cartesian doctrine. Physiology is, at present, incompetent to
say anything positively about the matter, or to go farther than the
expression of the high probability, that every molecular change
which gives rise to a state of consciousness, leaves a more or less
persistent structural modification, through which the same molecular
change may be regenerated by other agencies than the cause which first
produced it.

Thus far, the propositions respecting the physiology of the nervous
system which are stated by Descartes have simply been more clearly
defined, more fully illustrated, and, for the most part, demonstrated,
by modern physiological research. But there remains a doctrine to which
Descartes attached great weight, so that full acceptance of it became
a sort of note of a thorough-going Cartesian, but which, nevertheless,
is so opposed to ordinary prepossessions that it attained more general
notoriety, and gave rise to more discussion, than almost any other
Cartesian hypothesis. It is the doctrine, that brute animals are mere
machines or automata, devoid not only of reason, but of any kind of
consciousness, which is stated briefly in the “Discours de la Méthode,”
and more fully in the “Réponses aux Quatrièmes Objections,” and in the
correspondence with Henry More.[49]

The process of reasoning by which Descartes arrived at this startling
conclusion is well shown in the following passage of the “Réponses:”—

  “But as regards the souls of beasts, although this is not
  the place for considering them, and though, without a
  general exposition of physics, I can say no more on this
  subject than I have already said in the fifth part of my
  Treatise on Method; yet, I will further state, here, that
  it appears to me to be a very remarkable circumstance
  that no movement can take place, either in the bodies of
  beasts, or even in our own, if these bodies have not in
  themselves all the organs and instruments by means of
  which the very same movements would be accomplished in a
  machine. So that, even in us, the spirit, or the soul,
  does not directly move the limbs, but only determines
  the course of that very subtle liquid which is called
  the animal spirits, which, running continually from the
  heart by the brain into the muscles, is the cause of all
  the movements of our limbs, and often may cause many
  different motions, one as easily as the other.

  “And it does not even always exert this determination;
  for among the movements which take place in us, there
  are many which do not depend on the mind at all, such
  as the beating of the heart, the digestion of food, the
  nutrition, the respiration, of those who sleep; and,
  even in those who are awake, walking, singing, and other
  similar actions, when they are performed without the
  mind thinking about them. And, when one who falls from
  a height throws his hands forwards to save his head, it
  is in virtue of no ratiocination that he performs this
  action; it does not depend upon his mind, but takes place
  merely because his senses being affected by the present
  danger, some change arises in his brain which determines
  the animal spirits to pass thence into the nerves, in
  such a manner as is required to produce this motion,
  in the same way as in a machine, and without the mind
  being able to hinder it. Now since we observe this in
  ourselves, why should we be so much astonished if the
  light reflected from the body of a wolf into the eye of
  a sheep has the same force to excite in it the motion of
  flight?

  “After having observed this, if we wish to learn by
  reasoning, whether certain movements of beasts are
  comparable to those which are effected in us by the
  operation of the mind, or, on the contrary, to those
  which depend only on the animal spirits and the
  disposition of the organs, it is necessary to consider
  the difference between the two, which I have explained
  in the fifth part of the Discourse on Method (for I do
  not think that any others are discoverable), and then
  it will easily be seen, that all the actions of beasts
  are similar only to those which we perform without the
  help of our minds. For which reason we shall be forced
  to conclude, that we know of the existence in them of no
  other principle of motion than the disposition of their
  organs and the continual affluence of animal spirits
  produced by the heat of the heart, which attenuates and
  subtilises the blood; and, at the same time, we shall
  acknowledge that we have had no reason for assuming any
  other principle, except that, not having distinguished
  these two principles of motion, and seeing that the one,
  which depends only on the animal spirits and the organs,
  exists in beasts as well as in us, we have hastily
  concluded that the other, which depends on mind and on
  thought, was also possessed by them.”

Descartes’ line of argument is perfectly clear. He starts from reflex
action in man, from the unquestionable fact that, in ourselves,
co-ordinate, purposive, actions may take place, without the
intervention of consciousness or volition, or even contrary to the
latter. As actions of a certain degree of complexity are brought about
by mere mechanism, why may not actions of still greater complexity
be the result of a more refined mechanism? What proof is there that
brutes are other than a superior race of marionettes, which eat without
pleasure, cry without pain, desire nothing, know nothing, and only
simulate intelligence as a bee simulates a mathematician?[50]

The Port Royalists adopted the hypothesis that brutes are machines,
and are said to have carried its practical applications so far, as to
treat domestic animals with neglect, if not with actual cruelty. As
late as the middle of the eighteenth century, the problem was discussed
very fully and ably by Bouillier, in his “Essai philosophique sur l’Âme
des Bêtes,” while Condillac deals with it in his “Traité des Animaux;”
but since then it has received little attention. Nevertheless, modern
research has brought to light a great multitude of facts, which not
only show that Descartes’ view is defensible, but render it far more
defensible than it was in his day.

It must be premised, that it is wholly impossible absolutely to prove
the presence or absence of consciousness in anything but one’s own
brain, though, by analogy, we are justified in assuming its existence
in other men. Now if, by some accident, a man’s spinal cord is divided,
his limbs are paralysed, so far as his volition is concerned, below
the point of injury; and he is incapable of experiencing all those
states of consciousness, which, in his uninjured state, would be
excited by irritation of those nerves which come off below the injury.
If the spinal cord is divided in the middle of the back, for example,
the skin of the feet may be cut, or pinched, or burned, or wetted
with vitriol, without any sensation of touch, or of pain, arising in
consciousness. So far as the man is concerned, therefore, the part of
the central nervous system which lies beyond the injury is cut off
from consciousness. It must indeed be admitted, that, if any one think
fit to maintain that the spinal cord below the injury is conscious, but
that it is cut off from any means of making its consciousness known to
the other consciousness in the brain, there is no means of driving him
from his position by logic. But assuredly there is no way of proving
it, and in the matter of consciousness, if in anything, we may hold by
the rule, “De non apparentibus et de non existentibus eadem est ratio.”
However near the brain the spinal cord is injured, consciousness
remains intact, except that the irritation of parts below the injury
is no longer represented by sensation. On the other hand, pressure
upon the anterior division of the brain, or extensive injuries to it,
abolish consciousness. Hence, it is a highly probable conclusion,
that consciousness in man depends upon the integrity of the anterior
division of the brain, while the middle and hinder divisions of the
brain, and the rest of the nervous centres, have nothing to do with it.
And it is further highly probable, that what is true for man is true
for other vertebrated animals.

We may assume, then, that in a living vertebrated animal, any
segment of the cerebro-spinal axis (or spinal cord and brain)
separated from that anterior division of the brain which is the
organ of consciousness, is as completely incapable of giving rise to
consciousness, as we know it to be incapable of carrying out volitions.
Nevertheless, this separated segment of the spinal cord is not passive
and inert. On the contrary, it is the seat of extremely remarkable
powers. In our imaginary case of injury, the man would, as we have
seen, be devoid of sensation in his legs, and would have not the least
power of moving them. But, if the soles of his feet were tickled, the
legs would be drawn up, just as vigorously as they would have been
before the injury. We know exactly what happens when the soles of the
feet are tickled; a molecular change takes place in the sensory nerves
of the skin, and is propagated along them and through the posterior
roots of the spinal nerves, which are constituted by them, to the grey
matter of the spinal cord. Through that grey matter, the molecular
motion is reflected into the anterior roots of the same nerves,
constituted by the filaments which supply the muscles of the legs, and,
travelling along these motor filaments, reaches the muscles, which at
once contract, and cause the limbs to be drawn up.

In order to move the legs in this way, a definite co-ordination of
muscular contractions is necessary; the muscles must contract in a
certain order and with duly proportioned force; and moreover, as the
feet are drawn away from the source of irritation, it may be said that
the action has a final cause, or is purposive.

Thus it follows, that the grey matter of the segment of the man’s
spinal cord, though it is devoid of consciousness, nevertheless
responds to a simple stimulus by giving rise to a complex set of
muscular contractions, co-ordinated towards a definite end, and serving
an obvious purpose.

If the spinal cord of a frog is cut across, so as to provide us with a
segment separated from the brain, we shall have a subject parallel to
the injured man, on which experiments can be made without remorse; as
we have a right to conclude that a frog’s spinal cord is not likely to
be conscious, when a man’s is not.

Now the frog behaves just as the man did. The legs are utterly
paralysed, so far as voluntary movement is concerned; but they are
vigorously drawn up to the body when any irritant is applied to the
foot. But let us study our frog a little farther. Touch the skin of
the side of the body with a little acetic acid, which gives rise to
all the signs of great pain in an uninjured frog. In this case, there
can be no pain, because the application is made to a part of the skin
supplied with nerves which come off from the cord below the point of
section; nevertheless, the frog lifts up the limb of the same side,
and applies the foot to rub off the acetic acid; and, what is still
more remarkable, if the limb be held so that the frog cannot use it, it
will, by-and-by, move the limb of the other side, turn it across the
body, and use it for the same rubbing process. It is impossible that
the frog, if it were in its entirety and could reason, should perform
actions more purposive than these: and yet we have most complete
assurance that, in this case, the frog is not acting from purpose, has
no consciousness, and is a mere insensible machine.

But now suppose that, instead of making a section of the cord in the
middle of the body, it had been made in such a manner as to separate
the hindermost division of the brain from the rest of the organ, and
suppose the foremost two-thirds of the brain entirely taken away. The
frog is then absolutely devoid of any spontaneity; it sits upright in
the attitude which a frog habitually assumes; and it will not stir
unless it is touched; but it differs from the frog which I have just
described in this, that, if it be thrown into the water, it begins to
swim, and swims just as well as the perfect frog does. But swimming
requires the combination and successive co-ordination of a great number
of muscular actions. And we are forced to conclude, that the impression
made upon the sensory nerves of the skin of the frog by the contact
with the water into which it is thrown, causes the transmission to the
central nervous apparatus of an impulse, which sets going a certain
machinery by which all the muscles of swimming are brought into play
in due co-ordination. If the frog be stimulated by some irritating
body, it jumps or walks as well as the complete frog can do. The simple
sensory impression, acting through the machinery of the cord, gives
rise to these complex combined movements.

It is possible to go a step farther. Suppose that only the anterior
division of the brain—so much of it as lies in front of the “optic
lobes”—is removed. If that operation is performed quickly and
skilfully, the frog may be kept in a state of full bodily vigour for
months, or it may be for years; but it will sit unmoved. It sees
nothing; it hears nothing. It will starve sooner than feed itself,
although food put into its mouth is swallowed. On irritation, it jumps
or walks; if thrown into the water it swims. If it be put on the hand,
it sits there, crouched, perfectly quiet, and would sit there for ever.
If the hand be inclined very gently and slowly, so that the frog would
naturally tend to slip off, the creature’s fore paws are shifted on to
the edge of the hand, until he can just prevent himself from falling.
If the turning of the hand be slowly continued, he mounts up with great
care and deliberation, putting first one leg forward and then another,
until he balances himself with perfect precision upon the edge; and, if
the turning of the hand is continued, over he goes through the needful
set of muscular operations, until he comes to be seated in security,
upon the back of the hand. The doing of all this requires a delicacy of
co-ordination, and a precision of adjustment of the muscular apparatus
of the body, which are only comparable to those of a rope-dancer. To
the ordinary influences of light, the frog, deprived of its cerebral
hemispheres, appears to be blind. Nevertheless, if the animal be put
upon a table, with a book at some little distance between it and the
light, and the skin of the hinder part of its body is then irritated,
it will jump forward, avoiding the book by passing to the right or left
of it. Therefore, although the frog appears to have no sensation of
light, visible objects act through its brain upon the motor mechanism
of its body.[51]

It is obvious, that had Descartes been acquainted with these remarkable
results of modern research, they would have furnished him with far
more powerful arguments than he possessed in favour of his view of
the automatism of brutes. The habits of a frog, leading its natural
life, involve such simple adaptations to surrounding conditions,
that the machinery which is competent to do so much without the
intervention of consciousness, might well do all. And this argument is
vastly strengthened by what has been learned in recent times of the
marvellously complex operations which are performed mechanically, and
to all appearance without consciousness, by men, when, in consequence
of injury or disease, they are reduced to a condition more or less
comparable to that of a frog, in which the anterior part of the brain
has been removed. A case has recently been published by an eminent
French physician, Dr. Mesnet, which illustrates this condition so
remarkably, that I make no apology for dwelling upon it at considerable
length.[52]

A sergeant of the French army, F——, twenty-seven years of age, was
wounded during the battle of Bazeilles, by a ball which fractured his
left parietal bone. He ran his bayonet through the Prussian soldier who
wounded him, but almost immediately his right arm became paralysed;
after walking about two hundred yards, his right leg became similarly
affected, and he lost his senses. When he recovered them, three weeks
afterwards, in hospital at Mayence, the right half of the body was
completely paralysed, and remained in this condition for a year. At
present, the only trace of the paralysis which remains is a slight
weakness of the right half of the body. Three or four months after
the wound was inflicted, periodical disturbances of the functions of
the brain made their appearance, and have continued ever since. The
disturbances last from fifteen to thirty hours; the intervals at which
they occur being from fifteen to thirty days.

For four years, therefore, the life of this man has been divided into
alternating phases—short abnormal states intervening between long
normal states.

In the periods of normal life, the ex-sergeant’s health is perfect; he
is intelligent and kindly, and performs, satisfactorily, the duties of
a hospital attendant. The commencement of the abnormal state is ushered
in by uneasiness and a sense of weight about the forehead, which the
patient compares to the constriction of a circle of iron; and, after
its termination, he complains, for some hours, of dulness and heaviness
of the head. But the transition from the normal to the abnormal state
takes place in a few minutes, without convulsions or cries, and without
anything to indicate the change to a bystander. His movements remain
free and his expression calm, except for a contraction of the brow, an
incessant movement of the eyeballs, and a chewing motion of the jaws.
The eyes are wide open, and their pupils dilated. If the man happens to
be in a place to which he is accustomed, he walks about as usual; but,
if he is in a new place, or if obstacles are intentionally placed in
his way, he stumbles gently against them, stops, and then, feeling over
the objects with his hands, passes on one side of them. He offers no
resistance to any change of direction which may be impressed upon him,
or to the forcible acceleration or retardation of his movements. He
eats, drinks, smokes, walks about, dresses and undresses himself, rises
and goes to bed at the accustomed hours. Nevertheless, pins may be
run into his body, or strong electric shocks sent through it, without
causing the least indication of pain; no odorous substance, pleasant or
unpleasant, makes the least impression; he eats and drinks with avidity
whatever is offered, and takes asafœtida, or vinegar, or quinine, as
readily as water; no noise affects him; and light influences him only
under certain conditions. Dr. Mesnet remarks, that the sense of touch
alone seems to persist, and indeed to be more acute and delicate than
in the normal state; and it is by means of the nerves of touch, almost
exclusively, that his organism is brought into relation with the
external world. Here a difficulty arises. It is clear from the facts
detailed, that the nervous apparatus by which, in the normal state,
sensations of touch are excited, is that by which external influences
determine the movements of the body, in the abnormal state. But does
the state of consciousness, which we term a tactile sensation,
accompany the operation of this nervous apparatus in the abnormal
state? or is consciousness utterly absent, the man being reduced to an
insensible mechanism?

It is impossible to obtain direct evidence in favour of the one
conclusion or the other; all that can be said is, that the case of the
frog shows that the man may be devoid of any kind of consciousness.

A further difficult problem is this. The man is insensible to sensory
impressions made through the ear, the nose, the tongue, and, to a great
extent, the eye; nor is he susceptible of pain from causes operating
during his abnormal state. Nevertheless, it is possible so to act upon
his tactile apparatus, as to give rise to those molecular changes in
his sensorium, which are ordinarily the causes of associated trains of
ideas. I give a striking example of this process in Dr. Mesnet’s words:—

  “Il se promenait dans le jardin, sous un massif d’arbres,
  on lui remet à la main sa canne qu’il avait laissé
  tomber quelques minutes avant. Il la palpe, promène à
  plusieurs reprises la main sur la poignée coudée de
  sa canne—devient attentif—semble prêter l’oreille—et,
  tout-à-coup, appelle ‘Henri!’ Puis, ‘Les voilà! Ils sont
  au moins une vingtaine! à nous deux, nous en viendrons à
  bout!’ Et alors portant la main derrière son dos comme
  pour prendre une cartouche, il fait le mouvement de
  charger son arme, se couche dans l’herbe à plat ventre,
  la tête cachée par un arbre, dans la position d’un
  tirailleur, et suit, l’arme épaulée, tous les mouvements
  de l’ennemi qu’il croit voir à courte distance.”

In a subsequent abnormal period, Dr. Mesnet caused the patient to
repeat this scene by placing him in the same conditions. Now, in this
case, the question arises whether the series of actions constituting
this singular pantomime was accompanied by the ordinary states of
consciousness, the appropriate train of ideas, or not? Did the man
dream that he was skirmishing? or was he in the condition of one of
Vaucauson’s automata—a senseless mechanism worked by molecular changes
in his nervous system? The analogy of the frog shows that the latter
assumption is perfectly justifiable.

The ex-sergeant has a good voice, and had, at one time, been employed
as a singer at a café. In one of his abnormal states he was observed
to begin humming a tune. He then went to his room, dressed himself
carefully, and took up some parts of a periodical novel, which lay on
his bed, as if he were trying to find something. Dr. Mesnet, suspecting
that he was seeking his music, made up one of these into a roll and
put it into his hand. He appeared satisfied, took up his cane and went
down-stairs to the door. Here Dr. Mesnet turned him round, and he
walked quite contentedly, in the opposite direction, towards the room
of the concièrge. The light of the sun shining through a window now
happened to fall upon him, and seemed to suggest the footlights of the
stage on which he was accustomed to make his appearance. He stopped,
opened his roll of imaginary music, put himself into the attitude of a
singer, and sang, with perfect execution, three songs, one after the
other. After which he wiped his face with his handkerchief and drank,
without a grimace, a tumbler of strong vinegar and water which was put
into his hand.

An experiment which may be performed upon the frog deprived of the
fore part of its brain, well known as Göltz’s “Quak-versuch,” affords
a parallel to this performance. If the skin of a certain part of the
back of such a frog is gently stroked with the finger, it immediately
croaks. It never croaks unless it is so stroked, and the croak always
follows the stroke, just as the sound of a repeater follows the
touching of the spring. In the frog, this “song” is innate—so to speak
_à priori_—and depends upon a mechanism in the brain governing the
vocal apparatus, which is set at work by the molecular change set up in
the sensory nerves of the skin of the back by the contact of a foreign
body.

In man there is also a vocal mechanism, and the cry of an infant is
in the same sense innate and _à priori_, inasmuch as it depends on an
organic relation between its sensory nerves and the nervous mechanism
which governs the vocal apparatus. Learning to speak, and learning to
sing, are processes by which the vocal mechanism is set to new tunes.
A song which has been learned has its molecular equivalent, which
potentially represents it in the brain, just as a musical box wound up
potentially represents an overture. Touch the stop and the overture
begins; send a molecular impulse along the proper afferent nerve and
the singer begins his song.

Again, the manner in which the frog, though apparently insensible to
light, is yet, under some circumstances, influenced by visual images,
finds a singular parallel in the case of the ex-sergeant.

Sitting at a table, in one of his abnormal states, he took up a
pen, felt for paper and ink, and began to write a letter to his
general, in which he recommended himself for a medal, on account of
his good conduct and courage. It occurred to Dr. Mesnet to ascertain
experimentally how far vision was concerned in this act of writing. He
therefore interposed a screen between the man’s eyes and his hands;
under these circumstances he went on writing for a short time, but the
words became illegible, and he finally stopped, without manifesting
any discontent. On the withdrawal of the screen he began to write
again where he had left off. The substitution of water for ink in the
inkstand had a similar result. He stopped, looked at his pen, wiped it
on his coat, dipped it in the water, and began again, with the same
effect.

On one occasion, he began to write upon the topmost of ten superimposed
sheets of paper. After he had written a line or two, this sheet was
suddenly drawn away. There was a slight expression of surprise, but he
continued his letter on the second sheet exactly as if it had been the
first. This operation was repeated five times, so that the fifth sheet
contained nothing but the writer’s signature at the bottom of the page.
Nevertheless, when the signature was finished, his eyes turned to the
top of the blank sheet, and he went through the form of reading over
what he had written, a movement of the lips accompanying each word;
moreover, with his pen, he put in such corrections as were needed, in
that part of the blank page which corresponded with the position of the
words which required correction, in the sheets which had been taken
away. If the five sheets had been transparent, therefore, they would,
when superposed, have formed a properly written and corrected letter.

Immediately after he had written his letter, F—— got up, walked down
to the garden, made himself a cigarette, lighted and smoked it. He was
about to prepare another, but sought in vain for his tobacco-pouch,
which had been purposely taken away. The pouch was now thrust before
his eyes and put under his nose, but he neither saw nor smelt it; but,
when it was placed in his hand, he at once seized it, made a fresh
cigarette, and ignited a match to light the latter. The match was blown
out, and another lighted match placed close before his eyes, but he
made no attempt to take it; and, if his cigarette was lighted for him,
he made no attempt to smoke. All this time the eyes were vacant, and
neither winked, nor exhibited any contraction of the pupils. From these
and other experiments, Dr. Mesnet draws the conclusion that his patient
sees some things and not others; that the sense of sight is accessible
to all things which are brought into relation with him by the sense of
touch, and, on the contrary, insensible to things which lie outside
this relation. He sees the match he holds, and does not see any other.

Just so the frog “sees” the book which is in the way of his jump, at
the same time that isolated visual impressions take no effect upon
him.[53]

As I have pointed out, it is impossible to prove that F—— is absolutely
unconscious in his abnormal state, but it is no less impossible to
prove the contrary; and the case of the frog goes a long way to
justify the assumption that, in the abnormal state, the man is a mere
insensible machine.

If such facts as these had come under the knowledge of Descartes, would
they not have formed an apt commentary upon that remarkable passage in
the “Traité de l’Homme,” which I have quoted elsewhere,[54] but which
is worth repetition?—

  “All the functions which I have attributed to this
  machine (the body), as the digestion of food, the
  pulsation of the heart and of the arteries; the nutrition
  and the growth of the limbs; respiration, wakefulness,
  and sleep; the reception of light, sounds, odours,
  flavours, heat, and such like qualities, in the organs of
  the external senses; the impression of the ideas of these
  in the organ of common sensation and in the imagination;
  the retention or the impression of these ideas on the
  memory: the internal movements of the appetites and the
  passions; and lastly the external movements of all the
  limbs, which follow so aptly, as well the action of
  the objects which are presented to the senses, as the
  impressions which meet in the memory, that they imitate
  as nearly as possible those of a real man; I desire, I
  say, that you should consider that these functions in the
  machine naturally proceed from the mere arrangement of
  its organs, neither more nor less than do the movements
  of a clock, or other automaton, from that of its weights
  and its wheels; so that, so far as these are concerned,
  it is not necessary to conceive any other vegetative or
  sensitive soul, nor any other principle of motion or of
  life, than the blood and the spirits agitated by the fire
  which burns continually in the heart, and which is no
  wise essentially different from all the fires which exist
  in inanimate bodies.”

And would Descartes not have been justified in asking why we need deny
that animals are machines, when men, in a state of unconsciousness,
perform, mechanically, actions as complicated and as seemingly rational
as those of any animals?

But though I do not think that Descartes’ hypothesis can be positively
refuted, I am not disposed to accept it. The doctrine of continuity
is too well established for it to be permissible to me to suppose
that any complex natural phenomenon comes into existence suddenly,
and without being preceded by simpler modifications; and very strong
arguments would be needed to prove that such complex phenomena, as
those of consciousness, first make their appearance in man. We know,
that, in the individual man, consciousness grows from a dim glimmer to
its full light, whether we consider the infant advancing in years, or
the adult emerging from slumber and swoon. We know, further, that the
lower animals possess, though less developed, that part of the brain
which we have every reason to believe to be the organ of consciousness
in man; and as, in other cases, function and organ are proportional, so
we have a right to conclude it is with the brain; and that the brutes,
though they may not possess our intensity of consciousness, and though,
from the absence of language, they can have no trains of thoughts, but
only trains of feelings, yet have a consciousness which, more or less
distinctly, foreshadows our own.

I confess that, in view of the struggle for existence which goes on
in the animal world, and of the frightful quantity of pain with which
it must be accompanied, I should be glad if the probabilities were in
favour of Descartes’ hypothesis; but, on the other hand, considering
the terrible practical consequences to domestic animals which might
ensue from any error on our part, it is as well to err on the right
side, if we err at all, and deal with them as weaker brethren, who are
bound, like the rest of us, to pay their toll for living, and suffer
what is needful for the general good. As Hartley finely says, “We
seem to be in the place of God to them;” and we may justly follow the
precedents He sets in nature in our dealings with them.

But though we may see reason to disagree with Descartes’ hypothesis
that brutes are unconscious machines, it does not follow that he
was wrong in regarding them as automata. They may be more or less
conscious, sensitive, automata; and the view that they are such
conscious machines is that which is implicitly, or explicitly, adopted
by most persons. When we speak of the actions of the lower animals
being guided by instinct and not by reason, what we really mean is
that, though they feel as we do, yet their actions are the results
of their physical organisation. We believe, in short, that they are
machines, one part of which (the nervous system) not only sets the rest
in motion, and co-ordinates its movements in relation with changes
in surrounding bodies, but is provided with special apparatus, the
function of which is the calling into existence of those states of
consciousness which are termed sensations, emotions, and ideas. I
believe that this generally accepted view is the best expression of the
facts at present known.

It is experimentally demonstrable—any one who cares to run a pin into
himself may perform a sufficient demonstration of the fact—that a mode
of motion of the nervous system is the immediate antecedent of a state
of consciousness. All but the adherents of “Occasionalism,” or of the
doctrine of “Pre-established Harmony” (if any such now exist), must
admit that we have as much reason for regarding the mode of motion
of the nervous system as the cause of the state of consciousness, as
we have for regarding any event as the cause of another. How the one
phenomenon causes the other we know, as much or as little, as in any
other case of causation; but we have as much right to believe that the
sensation is an effect of the molecular change, as we have to believe
that motion is an effect of impact; and there is as much propriety in
saying that the brain evolves sensation, as there is in saying that an
iron rod, when hammered, evolves heat.

As I have endeavoured to show, we are justified in supposing that
something analogous to what happens in ourselves takes place in the
brutes, and that the affections of their sensory nerves give rise to
molecular changes in the brain, which again give rise to, or evolve,
the corresponding states of consciousness. Nor can there be any
reasonable doubt that the emotions of brutes, and such ideas as they
possess, are similarly dependent upon molecular brain changes. Each
sensory impression leaves behind a record in the structure of the
brain—an “ideagenous” molecule, so to speak, which is competent, under
certain conditions, to reproduce, in a fainter condition, the state of
consciousness which corresponds with that sensory impression; and it is
these “ideagenous molecules” which are the physical basis of memory.

It may be assumed, then, that molecular changes in the brain are the
causes of all the states of consciousness of brutes. Is there any
evidence that these states of consciousness may, conversely, cause
those molecular changes which give rise to muscular motion? I see
no such evidence. The frog walks, hops, swims, and goes through his
gymnastic performances quite as well without consciousness, and
consequently without volition, as with it; and, if a frog, in his
natural state, possesses anything corresponding with what we call
volition, there is no reason to think that it is anything but a
concomitant of the molecular changes in the brain which form part of
the series involved in the production of motion.

The consciousness of brutes would appear to be related to the mechanism
of their body simply as a collateral product of its working, and to
be as completely without any power of modifying that working as the
steam-whistle which accompanies the work of a locomotive engine is
without influence upon its machinery. Their volition, if they have
any, is an emotion indicative of physical changes, not a cause of such
changes.

This conception of the relations of states of consciousness with
molecular changes in the brain—of _psychoses_ with _neuroses_—does not
prevent us from ascribing free will to brutes. For an agent is free
when there is nothing to prevent him from doing that which he desires
to do. If a greyhound chases a hare, he is a free agent, because his
action is in entire accordance with his strong desire to catch the
hare; while so long as he is held back by the leash he is not free,
being prevented by external force from following his inclination.
And the ascription of freedom to the greyhound under the former
circumstances is by no means inconsistent with the other aspect of
the facts of the case—that he is a machine impelled to the chase, and
caused, at the same time, to have the desire to catch the game by the
impression which the rays of light proceeding from the hare make upon
his eyes, and through them upon his brain.

Much ingenious argument has, at various times, been bestowed upon the
question: How is it possible to imagine that volition, which is a state
of consciousness, and, as such, has not the slightest community of
nature with matter in motion, can act upon the moving matter of which
the body is composed, as it is assumed to do in voluntary acts? But
if, as is here suggested, the voluntary acts of brutes—or, in other
words, the acts which they desire to perform—are as purely mechanical
as the rest of their actions, and are simply accompanied by the state
of consciousness called volition, the inquiry, so far as they are
concerned, becomes superfluous. Their volitions do not enter into the
chain of causation of their actions at all.

The hypothesis that brutes are conscious automata is perfectly
consistent with any view that may be held respecting the often
discussed and curious question whether they have souls or not; and,
if they have souls, whether those souls are immortal or not. It is
obviously harmonious with the most literal adherence to the text
of Scripture concerning “the beast that perisheth;” but it is not
inconsistent with the amiable conviction ascribed by Pope to his
“untutored savage,” that when he passes to the happy hunting-grounds
in the sky, “his faithful dog shall bear him company.” If the brutes
have consciousness and no souls, then it is clear that, in them,
consciousness is a direct function of material changes; while, if
they possess immaterial subjects of consciousness, or souls, then,
as consciousness is brought into existence only as the consequence
of molecular motion of the brain, it follows that it is an indirect
product of material changes. The soul stands related to the body as the
bell of a clock to the works, and consciousness answers to the sound
which the bell gives out when it is struck.

Thus far I have strictly confined myself to the problem with which I
proposed to deal at starting—the automatism of brutes. The question
is, I believe, a perfectly open one, and I feel happy in running
no risk of either Papal or Presbyterian condemnation for the views
which I have ventured to put forward. And there are so very few
interesting questions which one is, at present, allowed to think out
scientifically—to go as far as reason leads, and stop where evidence
comes to an end—without speedily being deafened by the tattoo of “the
drum ecclesiastic”—that I have luxuriated in my rare freedom, and would
now willingly bring this disquisition to an end if I could hope that
other people would go no farther. Unfortunately, past experience debars
me from entertaining any such hope, even if

          “... that drum’s discordant sound
  Parading round and round and round,”

were not, at present, as audible to me, as it was to the mild poet who
ventured to express his hatred of drums in general, in that well-known
couplet.

It will be said, that I mean that the conclusions deduced from the
study of the brutes are applicable to man, and that the logical
consequences of such application are fatalism, materialism, and
atheism—whereupon the drums will beat the _pas de charge_.

One does not do battle with drummers; but I venture to offer a few
remarks for the calm consideration of thoughtful persons, untrammelled
by foregone conclusions, unpledged to shore-up tottering dogmas, and
anxious only to know the true bearings of the case.

It is quite true that, to the best of my judgment, the argumentation
which applies to brutes holds equally good of men; and, therefore, that
all states of consciousness in us, as in them, are immediately caused
by molecular changes of the brain-substance. It seems to me that in
men, as in brutes, there is no proof that any state of consciousness
is the cause of change in the motion of the matter of the organism. If
these positions are well based, it follows that our mental conditions
are simply the symbols in consciousness of the changes which take
place automatically in the organism; and that, to take an extreme
illustration, the feeling we call volition is not the cause of a
voluntary act, but the symbol of that state of the brain which is
the immediate cause of that act. We are conscious automata, endowed
with free will in the only intelligible sense of that much-abused
term—inasmuch as in many respects we are able to do as we like—but
none the less parts of the great series of causes and effects which, in
unbroken continuity, composes that which is, and has been, and shall
be—the sum of existence.

As to the logical consequences of this conviction of mine, I may be
permitted to remark that logical consequences are the scarecrows of
fools and the beacons of wise men. The only question which any wise man
can ask himself, and which any honest man will ask himself, is whether
a doctrine is true or false. Consequences will take care of themselves;
at most their importance can only justify us in testing with extra care
the reasoning process from which they result.

So that if the view I have taken did really and logically lead to
fatalism, materialism, and atheism, I should profess myself a fatalist,
materialist, and atheist; and I should look upon those who, while they
believed in my honesty of purpose and intellectual competency, should
raise a hue and cry against me, as people who by their own admission
preferred lying to truth, and whose opinions therefore were unworthy of
the smallest attention.

But, as I have endeavoured to explain on other occasions, I really have
no claim to rank myself among fatalistic, materialistic, or atheistic
philosophers. Not among fatalists, for I take the conception of
necessity to have a logical, and not a physical foundation; not among
materialists, for I am utterly incapable of conceiving the existence
of matter if there is no mind in which to picture that existence; not
among atheists, for the problem of the ultimate cause of existence is
one which seems to me to be hopelessly out of reach of my poor powers.
Of all the senseless babble I have ever had occasion to read, the
demonstrations of these philosophers who undertake to tell us all about
the nature of God would be the worst, if they were not surpassed by the
still greater absurdities of the philosophers who try to prove that
there is no God.

And if this personal disclaimer should not be enough, let me further
point out that a great many persons whose acuteness and learning will
not be contested, and whose Christian piety, and, in some cases, strict
orthodoxy, are above suspicion, have held more or less definitely the
view that man is a conscious automaton.

It is held, for example, in substance, by the whole school of
predestinarian theologians, typified by St. Augustine, Calvin, and
Jonathan Edwards—the great work of the latter on the will showing
in this, as in other cases, that the growth of physical science has
introduced no new difficulties of principle into theological problems,
but has merely given visible body, as it were, to those which already
existed.

Among philosophers, the pious Geulincx and the whole school of
occasionalist Cartesians held this view; the orthodox Leibnitz invented
the term “automate spirituel,” and applied it to man; the fervent
Christian, Hartley, was one of the chief advocates and best expositors
of the doctrine; while another zealous apologist of Christianity in
a sceptical age, and a contemporary of Hartley, Charles Bonnet, the
Genevese naturalist, has embodied the doctrine in language of such
precision and simplicity, that I will quote the little-known passage of
his “Essai de Psychologie” at length:—


“ANOTHER HYPOTHESIS CONCERNING THE MECHANISM OF IDEAS.[55]

  “Philosophers accustomed to judge of things by that which
  they are in themselves, and not by their relation to
  received ideas, would not be shocked if they met with
  the proposition that the soul is a mere spectator of
  the movements of its body: that the latter performs of
  itself all that series of actions which constitutes life:
  that it moves of itself: that it is the body alone which
  reproduces ideas, compares and arranges them; which forms
  reasonings, imagines and executes plans of all kinds,
  etc. This hypothesis, though perhaps of an excessive
  boldness, nevertheless deserves some consideration.

  “It is not to be denied that Supreme Power could create
  an automaton which should exactly imitate all the
  external and internal actions of man.

  “I understand by external actions, all those movements
  which pass under our eyes; I term internal actions, all
  the motions which in the natural state cannot be observed
  because they take place in the interior of the body—such
  as the movements of digestion, circulation, sensation,
  etc. Moreover, I include in this category the movements
  which give rise to ideas, whatever be their nature.

  “In the automaton which we are considering everything
  would be precisely determined. Everything would occur
  according to the rules of the most admirable mechanism:
  one state would succeed another state, one operation
  would lead to another operation, according to invariable
  laws; motion would become alternately cause and effect,
  effect and cause; reaction would answer to action, and
  reproduction to production.

  “Constructed with definite relations to the activity
  of the beings which compose the world, the automaton
  would receive impressions from it, and, in faithful
  correspondence thereto, it would execute a corresponding
  series of motions.

  “Indifferent towards any determination, it would yield
  equally to all, if the first impressions did not, so to
  speak, wind up the machine and decide its operations and
  its course.

  “The series of movements which this automaton could
  execute would distinguish it from all others formed on
  the same model, but which, not having been placed in
  similar circumstances, would not have experienced the
  same impressions, or would not have experienced them in
  the same order.

  “The senses of the automaton, set in motion by the
  objects presented to it, would communicate their motion
  to the brain, the chief motor apparatus of the machine.
  This would put in action the muscles of the hands and
  feet, in virtue of their secret connection with the
  senses. These muscles, alternately contracted and
  dilated, would approximate or remove the automaton from
  the objects, in the relation which they would bear to the
  conservation or the destruction of the machine.

  “The motions of perception and sensation which the
  objects would have impressed on the brain, would be
  preserved in it by the energy of its mechanism. They
  would become more vivid according to the actual condition
  of the automaton, considered in itself and relatively to
  the objects.

  “Words being only the motions impressed on the organ
  of hearing and that of voice, the diversity of these
  movements, their combination, the order in which they
  would succeed one another, would represent judgments,
  reasoning, and all the operations of the mind.

  “A close correspondence between the organs of the senses,
  either by the opening into one another of their nervous
  ramifications, or by interposed springs (_ressorts_),
  would establish such a connection in their working, that,
  on the occasion of the movements impressed on one of
  these organs, other movements would be excited, or would
  become more vivid in some of the other senses.

  “Give the automaton a soul which contemplates its
  movements, which believes itself to be the author of
  them, which has different volitions on the occasion of
  the different movements, and you will on this hypothesis
  construct a man.

  “But would this man be free? Can the feeling of our
  liberty, this feeling which is so clear and so distinct
  and so vivid as to persuade us that we are the authors of
  our actions, be conciliated with this hypothesis? If it
  removes the difficulty which attends the conception of
  the action of the soul on the body, on the other hand it
  leaves untouched that which meets us in endeavouring to
  conceive the action of the body on the soul.”

But if Leibnitz, Jonathan Edwards, and Hartley—men who rank among
the giants of the world of thought—could see no antagonism between
the doctrine under discussion and Christian orthodoxy, is it not
just possible that smaller folk may be wrong in making such a coil
about “logical consequences”? And, seeing how large a share of this
clamour is raised by the clergy of one denomination or another, may
I say, in conclusion, that it really would be well if ecclesiastical
persons would reflect that ordination, whatever deep-seated graces
it may confer, has never been observed to be followed by any visible
increase in the learning or the logic of its subject. Making a man a
Bishop, or entrusting him with the office of ministering to even the
largest of Presbyterian congregations, or setting him up to lecture to
a Church congress, really does not in the smallest degree augment such
title to respect as his opinions may intrinsically possess. And, when
such a man presumes on an authority which was conferred upon him for
other purposes, to sit in judgment upon matters his incompetence to
deal with which is patent, it is permissible to ignore his sacerdotal
pretensions, and to tell him, as one would tell a mere common,
unconsecrated, layman: that it is not necessary for any man to occupy
himself with problems of this kind unless he so choose; life is filled
full enough by the performance of its ordinary and obvious duties. But
that, if a man elect to become a judge of these grave questions; still
more, if he assume the responsibility of attaching praise or blame
to his fellow-men for the conclusions at which they arrive touching
them, he will commit a sin more grievous than most breaches of the
Decalogue, unless he avoid a lazy reliance upon the information that
is gathered by prejudice and filtered through passion, unless he go
back to the prime sources of knowledge—the facts of nature, and the
thoughts of those wise men who for generations past have been her best
interpreters.




X.

ON SENSATION AND THE UNITY OF STRUCTURE OF SENSIFEROUS ORGANS.


The maxim that metaphysical inquiries are barren of result, and that
the serious occupation of the mind with them is a mere waste of time
and labour, finds much favour in the eyes of the many persons who
pride themselves on the possession of sound common sense; and we
sometimes hear it enunciated by weighty authorities, as if its natural
consequence, the suppression of such studies, had the force of a moral
obligation.

In this case, however, as in some others, those who lay down the law
seem to forget that a wise legislator will consider, not merely whether
his proposed enactment is desirable, but whether obedience to it is
possible. For, if the latter question is answered negatively, the
former is surely hardly worth debate.

Here, in fact, lies the pith of the reply to those who would make
metaphysics contraband of intellect. Whether it is desirable to
place a prohibitory duty upon philosophical speculations or not, it
is utterly impossible to prevent the importation of them into the
mind. And it is not a little curious to observe that those who most
loudly profess to abstain from such commodities are, all the while,
unconscious consumers, on a great scale, of one or other of their
multitudinous disguises or adulterations. With mouths full of the
particular kind of heavily buttered toast which they affect, they
inveigh against the eating of plain bread. In truth, the attempt to
nourish the human intellect upon a diet which contains no metaphysics
is about as hopeful as that of certain Eastern sages to nourish their
bodies without destroying life. Everybody has heard the story of the
pitiless microscopist, who ruined the peace of mind of one of these
mild enthusiasts by showing him the animals moving in a drop of the
water with which, in the innocency of his heart, he slaked his thirst;
and the unsuspecting devotee of plain common sense may look for as
unexpected a shock when the magnifier of severe logic reveals the
germs, if not the full-grown shapes, of lively metaphysical postulates
rampant amidst his most positive and matter-of-fact notions.

By way of escape from the metaphysical Will-o’-the-wisps generated
in the marshes of literature and theology, the serious student is
sometimes bidden to betake himself to the solid ground of physical
science. But the fish of immortal memory, who threw himself out of the
frying-pan into the fire, was not more ill advised than the man who
seeks sanctuary from philosophical persecution within the walls of
the observatory or of the laboratory. It is said that “metaphysics”
owe their name to the fact that, in Aristotle’s works, questions of
pure philosophy are dealt with immediately after those of physics. If
so, the accident is happily symbolical of the essential relations of
things; for metaphysical speculation follows as closely upon physical
theory as black care upon the horseman.

One need but mention such fundamental, and indeed indispensable,
conceptions of the natural philosopher as those of atoms and forces:
or that of attraction considered as action at a distance; or that of
potential energy; or the antinomies of a vacuum and a plenum; to call
to mind the metaphysical background of physics and chemistry; while, in
the biological sciences, the case is still worse. What is an individual
among the lower plants and animals? Are genera and species realities or
abstractions? Is there such a thing as Vital Force? or does the name
denote a mere relic of metaphysical fetichism? Is the doctrine of final
causes legitimate or illegitimate? These are a few of the metaphysical
topics which are suggested by the most elementary study of biological
facts. But, more than this, it may be truly said that the roots of
every system of philosophy lie deep among the facts of physiology. No
one can doubt that the organs and the functions of sensation are as
much a part of the province of the physiologist, as are the organs and
functions of motion, or those of digestion; and yet it is impossible
to gain an acquaintance with even the rudiments of the physiology of
sensation without being led straight to one of the most fundamental of
all metaphysical problems. In fact, the sensory operations have been,
from time immemorial, the battle-ground of philosophers.

I have more than once taken occasion to point out that we are
indebted to Descartes, who happened to be a physiologist as well as
a philosopher, for the first distinct enunciation of the essential
elements of the true theory of sensation. In later times, it is not to
the works of the philosophers, if Hartley and James Mill are excepted,
but to those of the physiologists, that we must turn for an adequate
account of the sensory process. Haller’s luminous, though summary,
account of sensation in his admirable “Primæ Lineæ,” the first edition
of which was printed in 1747, offers a striking contrast to the
prolixity and confusion of thought which pervade Reid’s “Inquiry,” of
seventeen years’ later date.[56] Even Sir William Hamilton, learned
historian and acute critic as he was, not only failed to apprehend the
philosophical bearing of long-established physiological truths; but,
when he affirmed that there is no reason to deny that the mind feels at
the finger points, and none to assert that the brain is the sole organ
of thought,[57] he showed that he had not apprehended the significance
of the revolution commenced, two hundred years before his time, by
Descartes, and effectively followed up by Haller, Hartley, and Bonnet,
in the middle of the last century.

In truth, the theory of sensation, except in one point, is, at the
present moment, very much where Hartley, led by a hint of Sir Isaac
Newton’s, left it, when, a hundred and twenty years since, the
“Observations on Man: his Frame, his Duty, and his Expectations,” was
laid before the world. The whole matter is put in a nutshell in the
following passages of this notable book.

  “External objects impressed upon the senses occasion,
  first on the nerves on which they are impressed, and then
  on the brain, vibrations of the small and, as we may say,
  infinitesimal medullary particles.

  “These vibrations are motions backwards and forwards
  of the small particles; of the same kind with the
  oscillations of pendulums and the tremblings of the
  particles of sounding bodies. They must be conceived to
  be exceedingly short and small, so as not to have the
  least efficacy to disturb or move the whole bodies of the
  nerves or brain.”[58]

  “The white medullary substance of the brain is also the
  immediate instrument by which ideas are presented to
  the mind; or, in other words, whatever changes are made
  in this substance, corresponding changes are made in our
  ideas; and _vice versa_.”[59]

Hartley, like Haller, had no conception of the nature and functions of
the grey matter of the brain. But, if for “white medullary substance,”
in the latter paragraph, we substitute “grey cellular substance,”
Hartley’s propositions embody the most probable conclusions which are
to be drawn from the latest investigations of physiologists. In order
to judge how completely this is the case, it will be well to study some
simple case of sensation, and, following the example of Reid and of
James Mill, we may begin with the sense of smell. Suppose that I become
aware of a musky scent, to which the name of “muskiness” may be given.
I call this an odour, and I class it along with the feelings of light,
colours, sounds, tastes, and the like, among those phenomena which are
known as sensations. To say that I am aware of this phenomenon, or that
I have it, or that it exists, are simply different modes of affirming
the same facts. If I am asked how I know that it exists, I can only
reply that its existence and my knowledge of it are one and the same
thing; in short, that my knowledge is immediate or intuitive, and, as
such, is possessed of the highest conceivable degree of certainty.

The pure sensation of muskiness is almost sure to be followed by
a mental state which is not a sensation, but a belief, that there
is somewhere close at hand a something on which the existence of
the sensation depends. It may be a musk-deer, or a musk-rat, or a
musk-plant, or a grain of dry musk, or simply a scented handkerchief;
but former experience leads us to believe that the sensation is due to
the presence of one or other of these objects, and that it will vanish
if the object is removed. In other words, there arises a belief in an
external cause of the muskiness, which, in common language, is termed
an odorous body.

But the manner in which this belief is usually put into words is
strangely misleading. If we are dealing with a musk-plant, for example,
we do not confine ourselves to a simple statement of that which we
believe, and say that the musk-plant is the cause of the sensation
called muskiness; but we say that the plant has a musky smell, and
we speak of the odour as a quality, or property, inherent in the
plant. And the inevitable reaction of words upon thought has in this
case become so complete, and has penetrated so deeply, that when an
accurate statement of the case—namely, that muskiness, inasmuch as
the term denotes nothing but a sensation, is a mental state, and has
no existence except as a mental phenomenon—is first brought under the
notice of common-sense folks, it is usually regarded by them as what
they are pleased to call a mere metaphysical paradox and a patent
example of useless subtlety. Yet the slightest reflection must suffice
to convince any one possessed of sound reasoning faculties, that it is
as absurd to suppose that muskiness is a quality inherent in one plant,
as it would be to imagine that pain is a quality inherent in another,
because we feel pain when a thorn pricks the finger.

Even the common-sense philosopher, _par excellence_, says of smell: “It
appears to be a simple and original affection or feeling of the mind,
altogether inexplicable and unaccountable. It is indeed impossible that
it can be in any body: it is a sensation, and a sensation can only be
in a sentient thing.”[60]

That which is true of muskiness is true of every other odour.
Lavender-smell, clove-smell, garlic-smell, are, like “muskiness,” names
of states of consciousness, and have no existence except as such.
But, in ordinary language, we speak of all these odours as if they
were independent entities residing in lavender, cloves, and garlic;
and it is not without a certain struggle that the false metaphysic of
so-called common sense, thus ingrained in us, is expelled.

For the present purpose, it is unnecessary to inquire into the origin
of our belief in external bodies, or into that of the notion of
causation. Assuming the existence of an external world, there is no
difficulty in obtaining experimental proof that, as a general rule,
olfactory sensations are caused by odorous bodies; and we may pass on
to the next step of the inquiry—namely, how the odorous body produces
the effect attributed to it.

The first point to be noted here is another fact revealed by
experience; that the appearance of the sensation is governed, not only
by the presence of the odorous substance, but by the condition of a
certain part of our corporeal structure, the nose. If the nostrils are
closed, the presence of the odorous substance does not give rise to
the sensation; while, when they are open, the sensation is intensified
by the approximation of the odorous substance to them, and by snuffing
up the adjacent air in such a manner as to draw it into the nose. On
the other hand, looking at an odorous substance, or rubbing it on the
skin, or holding it to the ear, does not awaken the sensation. Thus,
it can be readily established by experiment that the perviousness of
the nasal passages is, in some way, essential to the sensory function;
in fact, that the organ of that function is lodged somewhere in the
nasal passages. And, since odorous bodies give rise to their effects at
considerable distances, the suggestion is obvious that something must
pass from them into the sense organ. What is this “something,” which
plays the part of an intermediary between the odorous body and the
sensory organ?

The oldest speculation about the matter dates back to Democritus and
the Epicurean School, and it is to be found fully stated in the fourth
book of Lucretius. It comes to this: that the surfaces of bodies
are constantly throwing off excessively attenuated films of their
own substance: and that these films, reaching the mind, excite the
appropriate sensations in it.

Aristotle did not admit the existence of any such material films, but
conceived that it was the form of the substance, and not its matter,
which affected sense, as a seal impresses wax, without losing anything
in the process. While many, if not the majority, of the Schoolmen took
up an intermediate position and supposed that a something, which was
not exactly either material or immaterial, and which they called an
“intentional species,” effected the needful communication between the
bodily cause of sensation and the mind.

But all these notions, whatever may be said for or against them in
general, are fundamentally defective, by reason of an oversight
which was inevitable, in the state of knowledge at the time in which
they were promulgated. What the older philosophers did not know, and
could not know, before the anatomist and the physiologist had done
their work, is that, between the external object and that mind in
which they supposed the sensation to inhere, there lies a physical
obstacle. The sense organ is not a mere passage by which the “tenuia
simulacra rerum,” or the “intentional species” cast off by objects,
or the “forms” of sensible things, pass straight to the mind; on the
contrary, it stands as a firm and impervious barrier, through which no
material particle of the world without can make its way to the world
within.

Let us consider the olfactory sense organ more nearly. Each of the
nostrils leads into a passage completely separated from the other
by a partition, and these two passages place the nostrils in free
communication with the back of the throat, so that they freely transmit
the air passing to the lungs when the mouth is shut, as in ordinary
breathing. The floor of each passage is flat, but its roof is a high
arch, the crown of which is seated between the orbital cavities of the
skull, which serve for the lodgment and protection of the eyes; and
it therefore lies behind the apparent limits of that feature which,
in ordinary language, is called the nose. From the side walls of the
upper and back part of these arched chambers, certain delicate plates
of bone project, and these, as well as a considerable part of the
partition between the two chambers, are covered by a fine, soft, moist
membrane. It is to this “Schneiderian,” or olfactory, membrane that
odorous bodies must obtain direct access, if they are to give rise
to their appropriate sensations; and it is upon the relatively large
surface, which the olfactory membrane offers, that we must seek for
the seat of the organ of the olfactory sense. The only essential part
of that organ consists of a multitude of minute rod-like bodies, set
perpendicularly to the surface of the membrane, and forming a part of
the cellular coat, or epithelium, which covers the olfactory membrane,
as the epidermis covers the skin. In the case of the olfactory sense,
there can be no doubt that the Democritic hypothesis, at any rate for
such odorous substances as musk, has a good foundation. Infinitesimal
particles of musk fly off from the surface of the odorous body, and,
becoming diffused through the air, are carried into the nasal passages,
and thence into the olfactory chambers, where they come into contact
with the filamentous extremities of the delicate olfactory epithelium.

But this is not all. The “mind” is not, so to speak, upon the other
side of the epithelium. On the contrary, the inner ends of the
olfactory cells are connected with nerve fibres, and these nerve
fibres, passing into the cavity of the skull, at length end in a
part of the brain, the olfactory sensorium. It is certain that the
integrity of each, and the physical inter-connection of all these three
structures, the epithelium of the sensory organ, the nerve fibres,
and the sensorium, are essential conditions of ordinary sensation.
That is to say, the air in the olfactory chambers may be charged with
particles of musk; but, if either the epithelium, or the nerve fibres,
or the sensorium is injured, or if they are physically disconnected
from one another, sensation will not arise. Moreover, the epithelium
may be said to be receptive, the nerve fibres transmissive, and the
sensorium sensifacient. For, in the act of smelling, the particles of
the odorous substance produce a molecular change (which Hartley was in
all probability right in terming a vibration) in the epithelium, and
this change being transmitted to the nerve fibres, passes along them
with a measurable velocity, and, finally reaching the sensorium, is
immediately followed by the sensation.

Thus, modern investigation supplies a representative of the Epicurean
simulacra in the volatile particles of the musk; but it also gives us
the stamp of the particles on the olfactory epithelium, without any
transmission of matter, as the equivalent of the Aristotelian “form;”
while, finally, the modes of motion of the molecules of the olfactory
cells, of the nerve, and of the cerebral sensorium, which are Hartley’s
vibrations, may stand very well for a double of the “intentional
species” of the Schoolmen. And this last remark is not intended merely
to suggest a fanciful parallel; for, if the cause of the sensation is,
as analogy suggests, to be sought in the mode of motion of the object
of sense, then it is quite possible that the particular mode of motion
of the object is reproduced in the sensorium; exactly as the diaphragm
of a telephone reproduces the mode of motion taken up at its receiving
end. In other words, the secondary “intentional species” may be, as the
Schoolmen thought the primary one was, the last link between matter and
mind.

None the less, however, does it remain true that no similarity exists,
nor indeed is conceivable, between the cause of the sensation and the
sensation. Attend as closely to the sensations of muskiness, or any
other odour, as we will, no trace of extension, resistance, or motion
is discernible in them. They have no attribute in common with those
which we ascribe to matter; they are, in the strictest sense of the
words, immaterial entities.

Thus, the most elementary study of sensation justifies Descartes’
position, that we know more of mind than we do of body; that the
immaterial world is a firmer reality than the material. For the
sensation “muskiness” is known immediately. So long as it persists,
it is a part of what we call our thinking selves, and its existence
lies beyond the possibility of doubt. The knowledge of an objective or
material cause of the sensation, on the other hand, is mediate; it is
a belief as contradistinguished from an intuition; and it is a belief
which, in any given instance of sensation, may, by possibility, be
devoid of foundation. For odours, like other sensations, may arise from
the occurrence of the appropriate molecular changes in the nerve or in
the sensorium, by the operation of a cause distinct from the affection
of the sense organ by an odorous body. Such “subjective” sensations
are as real existences as any others, and as distinctly suggest an
external odorous object as their cause; but the belief thus generated
is a delusion. And, if beliefs are properly termed “testimonies of
consciousness,” then undoubtedly the testimony of consciousness may be,
and often is, untrustworthy.

Another very important consideration arises out of the facts as they
are now known. That which, in the absence of a knowledge of the
physiology of sensation, we call the cause of the smell, and term the
odorous object, is only such, mediately, by reason of its emitting
particles which give rise to a mode of motion in the sense organ. The
sense organ, again, is only a mediate cause by reason of its producing
a molecular change in the nerve fibre; while this last change is also
only a mediate cause of sensation, depending, as it does, upon the
change which it excites in the sensorium.

The sense organ, the nerve, and the sensorium, taken together,
constitute the sensiferous apparatus. They make up the thickness of the
wall between the mind, as represented by the sensation “muskiness,” and
the object, as represented by the particle of musk in contact with the
olfactory epithelium.

It will be observed that the sensiferous wall and the external world
are of the same nature; whatever it is that constitutes them both is
expressible in terms of matter and motion. Whatever changes take place
in the sensiferous apparatus are continuous with, and similar to, those
which take place in the external world.[61] But, with the sensorium,
matter and motion come to an end; while phenomena of another order,
or immaterial states of consciousness, make their appearance. How is
the relation between the material and the immaterial phenomena to
be conceived? This is the metaphysical problem of problems, and the
solutions which have been suggested have been made the corner-stones of
systems of philosophy. Three mutually irreconcilable readings of the
riddle have been offered.

The first is, that an immaterial substance of mind exists; and that it
is affected by the mode of motion of the sensorium in such a way as to
give rise to the sensation.

The second is, that the sensation is a direct effect of the mode of
motion of the sensorium, brought about without the intervention of any
substance of mind.

The third is, that the sensation is neither directly nor indirectly
an effect of the mode of motion of the sensorium, but that it has an
independent cause. Properly speaking, therefore, it is not an effect of
the motion of the sensorium, but a concomitant of it.

As none of these hypotheses is capable of even an approximation to
demonstration, it is almost needless to remark that they have been
severally held with tenacity and advocated with passion. I do not
think it can be said of any of the three that it is inconceivable, or
that it can be assumed on _à priori_ grounds to be impossible.

Consider the first, for example; an immaterial substance is perfectly
conceivable. In fact, it is obvious that, if we possessed no sensations
but those of smell and hearing, we should be unable to conceive a
material substance. We might have a conception of time, but could
have none of extension, or of resistance, or of motion. And without
the three latter conceptions no idea of matter could be formed. Our
whole knowledge would be limited to that of a shifting succession
of immaterial phenomena. But, if an immaterial substance may exist,
it may have any conceivable properties; and sensation may be one of
them. All these propositions may be affirmed with complete dialectic
safety, inasmuch as they cannot possibly be disproved; but neither
can a particle of demonstrative evidence be offered in favour of the
existence of an immaterial substance.

As regards the second hypothesis, it certainly is not inconceivable,
and therefore it may be true, that sensation is the direct effect of
certain kinds of bodily motion. It is just as easy to suppose this as
to suppose, on the former hypothesis, that bodily motion affects an
immaterial substance. But neither is it susceptible of proof.

And, as to the third hypothesis, since the logic of induction is in no
case competent to prove that events apparently standing in the relation
of cause and effect may not both be effects of a common cause—that
also is as safe from refutation, if as incapable of demonstration, as
the other two.

In my own opinion, neither of these speculations can be regarded
seriously as anything but a more or less convenient working hypothesis.
But, if I must choose among them, I take the “law of parsimony” for my
guide, and select the simplest—namely, that the sensation is the direct
effect of the mode of motion of the sensorium. It may justly be said
that this is not the slightest explanation of sensation; but then am
I really any the wiser, if I say that a sensation is an activity (of
which I know nothing) of a substance of mind (of which also I know
nothing)? Or, if I say that the Deity causes the sensation to arise in
my mind immediately after He has caused the particles of the sensorium
to move in a certain way, is anything gained? In truth, a sensation, as
we have already seen, is an intuition—a part of immediate knowledge.
As such, it is an ultimate fact and inexplicable; and all that we
can hope to find out about it, and that indeed is worth finding out,
is its relation to other natural facts. That relation appears to me
to be sufficiently expressed, for all practical purposes, by saying
that sensation is the invariable consequent of certain changes in the
sensorium—or, in other words, that, so far as we know, the change in
the sensorium is the cause of the sensation.

I permit myself to imagine that the untutored, if noble, savage of
“common sense” who has been misled into reading thus far by the hope
of getting positive solid information about sensation, giving way to
not unnatural irritation, may here interpellate: “The upshot of all
this long disquisition is that we are profoundly ignorant. We knew
that to begin with, and you have merely furnished another example of
the emptiness and uselessness of metaphysics.” But I venture to reply,
Pardon me, you were ignorant, but you did not know it. On the contrary,
you thought you knew a great deal, and were quite satisfied with the
particularly absurd metaphysical notions which you were pleased to
call the teachings of common sense. You thought that your sensations
were properties of external things, and had an existence outside of
yourself. You thought that you knew more about material than you do
about immaterial existences. And if, as a wise man has assured us,
the knowledge of what we don’t know is the next best thing to the
knowledge of what we do know, this brief excursion into the province of
philosophy has been highly profitable.

Of all the dangerous mental habits, that which schoolboys call
“cocksureness” is probably the most perilous; and the inestimable
value of metaphysical discipline is that it furnishes an effectual
counterpoise to this evil proclivity. Whoso has mastered the elements
of philosophy knows that the attribute of unquestionable certainty
appertains only to the existence of a state of consciousness so long
as it exists; all other beliefs are mere probabilities of a higher or
lower order. Sound metaphysic is an amulet which renders its possessor
proof alike against the poison of superstition and the counter-poison
of nihilism; by showing that the affirmations of the former and the
denials of the latter alike deal with matters about which, for lack of
evidence, nothing can be either affirmed or denied.


I have dwelt at length upon the nature and origin of our sensations of
smell, on account of the comparative freedom of the olfactory sense
from the complications which are met with in most of the other senses.

Sensations of taste, however, are generated in almost as simple a
fashion as those of smell. In this case, the sense organ is the
epithelium which covers the tongue and the palate: and which sometimes,
becoming modified, gives rise to peculiar organs termed “gustatory
bulbs,” in which the epithelial cells elongate and assume a somewhat
rod-like form. Nerve fibres connect the sensory organ with the
sensorium, and tastes or flavours are states of consciousness caused
by the change of molecular state of the latter. In the case of the
sense of touch there is often no sense organ distinct from the general
epidermis. But many fishes and amphibia exhibit local modifications
of the epidermic cells which are sometimes extraordinarily like the
gustatory bulbs; more commonly, both in lower and higher animals,
the effect of the contact of external bodies is intensified by the
development of hair-like filaments, or of true hairs, the bases of
which are in immediate relation with the ends of the sensory nerves.
Every one must have noticed the extreme delicacy of the sensations
produced by the contact of bodies with the ends of the hairs of the
head; and the “whiskers” of cats owe their functional importance to
the abundant supply of nerves to the follicles in which their bases
are lodged. What part, if any, the so-called “tactile corpuscles,”
“end bulbs,” and “Pacinian bodies,” play in the mechanism of touch is
unknown. If they are sense organs, they are exceptional in character,
in so far as they do not appear to be modifications of the epidermis.
Nothing is known respecting the organs of those sensations of
resistance which are grouped under the head of the muscular sense;
nor of the sensations of warmth and cold; nor of that very singular
sensation which we call tickling.

In the case of heat and cold, the organism not only becomes affected
by external bodies, far more remote than those which affect the
sense of smell; but the Democritic hypothesis is obviously no longer
permissible. When the direct rays of the sun fall upon the skin,
the sensation of heat is certainly not caused by “attenuated films”
thrown off from that luminary, but is due to a mode of motion which is
transmitted to us. In Aristotelian phrase, it is the form without the
matter of the sun which stamps the sense organ; and this, translated
into modern language, means nearly the same thing as Hartley’s
vibrations. Thus we are prepared for what happens in the case of
the auditory and the visual senses. For neither the ear, nor the
eye, receives anything but the impulses or vibrations originated by
sonorous or luminous bodies. Nevertheless, the receptive apparatus
still consists of nothing but specially modified epithelial cells.
In the labyrinth of the ear of the higher animals, the free ends of
these cells terminate in excessively delicate hair-like filaments;
while, in the lower forms of auditory organ, its free surface is
beset with delicate hairs like those of the surface of the body, and
the transmissive nerves are connected with the bases of these hairs.
Thus there is an insensible gradation in the forms of the receptive
apparatus, from the organ of touch, on the one hand, to those of taste
and smell; and, on the other hand, to that of hearing. Even in the
case of the most refined of all the sense organs, that of vision, the
receptive apparatus departs but little from the general type. The
only essential constituent of the visual sense organ is the retina,
which forms so small a part of the eyes of the higher animals; and the
simplest eyes are nothing but portions of the integument, in which
the cells of the epidermis have become converted into glassy rod-like
retinal corpuscles. The outer ends of these are turned towards the
light; their sides are more or less extensively coated with a dark
pigment, and their inner ends are connected with the transmissive nerve
fibres. The light, impinging on these visual rods, produces a change in
them which is communicated to the nerve fibres, and, being transmitted
to the sensorium, gives rise to the sensation—if indeed all animals
which possess eyes are endowed with what we understand as sensation.

In the higher animals, a complicated apparatus of lenses, arranged
on the principle of a camera obscura, serves at once to concentrate
and to individualise the pencils of light proceeding from external
bodies. But the essential part of the organ of vision is still a layer
of cells, which have the form of rods with truncated or conical ends.
By what seems a strange anomaly, however, the glassy ends of these are
turned not towards, but away from, the light; and the latter has to
traverse the layer of nervous tissues with which their outer ends are
connected, before it can affect them. Moreover, the rods and cones of
the vertebrate retina are so deeply seated, and in many respects so
peculiar in character, that it appears impossible, at first sight, that
they can have anything to do with that epidermis of which gustatory and
tactile, and at any rate the lower forms of auditory and visual, organs
are obvious modifications.

Whatever be the apparent diversities among the sensiferous apparatuses,
however, they share certain common characters. Each consists of a
receptive, a transmissive, and a sensificatory portion. The essential
part of the first is an epithelium, of the second, nerve fibres, of the
third, a part of the brain; the sensation is always the consequence
of the mode of motion excited in the receptive, and sent along the
transmissive, to the sensificatory part of the sensiferous apparatus.
And, in all the senses, there is no likeness whatever between the
object of sense, which is matter in motion, and the sensation, which is
an immaterial phenomenon.

On the hypothesis which appears to me to be the most convenient,
sensation is a product of the sensiferous apparatus caused by certain
modes of motion which are set up in it by impulses from without. The
sensiferous apparatuses are, as it were, factories, all of which at
the one end receive raw materials of a similar kind—namely, modes of
motion—while, at the other, each turns out a special product, the
feeling which constitutes the kind of sensation characteristic of it.

Or, to make use of a closer comparison, each sensiferous apparatus is
comparable to a musical-box wound up; with as many tunes as there are
separate sensations. The object of a simple sensation is the agent
which presses down the stop of one of these tunes, and the more feeble
the agent, the more delicate must be the mobility of the stop.[62]

But, if this be true, if the recipient part of the sensiferous
apparatus is, in all cases, merely a mechanism affected by coarser or
finer kinds of material motion, we might expect to find that all sense
organs are fundamentally alike, and result from the modification of the
same morphological elements. And this is exactly what does result from
all recent histological and embryological investigations.

It has been seen that the receptive part of the olfactory apparatus is
a slightly modified epithelium, which lines an olfactory chamber deeply
seated between the orbits in adult human beings. But, if we trace back
the nasal chambers to their origin in the embryo, we find, that, to
begin with, they are mere depressions of the skin of the fore part
of the head, lined by a continuation of the general epidermis. These
depressions become pits, and the pits, by the growth of the adjacent
parts, gradually acquire the position which they finally occupy. The
olfactory organ, therefore, is a specially modified part of the general
integument.

The human ear would seem to present greater difficulties. For the
essential part of the sense organ, in this case, is the membranous
labyrinth, a bag of complicated form, which lies buried in the depths
of the floor of the skull, and is surrounded by dense and solid bone.
Here, however, recourse to the study of development readily unravels
the mystery. Shortly after the time when the olfactory organ appears,
as a depression of the skin on the side of the fore part of the head,
the auditory organ appears as a similar depression on the side of its
back part. The depression, rapidly deepening, becomes a small pouch;
and then, the communication with the exterior becoming shut off, the
pouch is converted into a closed bag, the epithelial lining of which is
a part of the general epidermis segregated from the rest. The adjacent
tissues, changing first into cartilage and then into bone, enclose
the auditory sac in a strong case, in which it undergoes its further
metamorphoses; while the drum, the ear bones, and the external ear,
are superadded by no less extraordinary modifications of the adjacent
parts. Still more marvellous is the history of the development of the
organ of vision. In the place of the eye, as in that of the nose and
that of the ear, the young embryo presents a depression of the general
integument; but, in man and the higher animals, this does not give
rise to the proper sensory organ, but only to part of the accessory
structures concerned in vision. In fact, this depression, deepening
and becoming converted into a shut sac, produces only the cornea, the
aqueous humour, and the crystalline lens of the perfect eye.

The retina is added to this by the outgrowth of the wall of a portion
of the brain into a sort of bag, or sac, with a narrow neck, the convex
bottom of which is turned outwards, or towards the crystalline lens.
As the development of the eye proceeds, the convex bottom of the bag
becomes pushed in, so that it gradually obliterates the cavity of the
sac, the previously convex wall of which becomes deeply concave. The
sac of the brain is now like a double nightcap ready for the head, but
the place which the head would occupy is taken by the vitreous humour,
while the layer of nightcap next it becomes the retina. The cells of
this layer which lie farthest from the vitreous humour, or, in other
words, bound the original cavity of the sac, are metamorphosed into
the rods and cones. Suppose now that the sac of the brain could be
brought back to its original form; then the rods and cones would form
part of the lining of a side pouch of the brain. But one of the most
wonderful revelations of embryology is the proof of the fact that the
brain itself is, at its first beginning, merely an infolding of the
epidermic layer of the general integument. Hence it follows that the
rods and cones of the vertebrate eye are modified epidermic cells, as
much as the crystalline cones of the insect or crustacean eye are; and
that the inversion of the position of the former in relation to light
arises simply from the roundabout way in which the vertebrate retina is
developed.

Thus all the higher sense organs start from one foundation, and the
receptive epithelium of the eye, or of the ear, is as much modified
epidermis as is that of the nose. The structural unity of the sense
organs is the morphological parallel to their identity of physiological
function, which, as we have seen, is to be impressed by certain modes
of motion; and they are fine or coarse, in proportion to the delicacy
or the strength of the impulses by which they are to be affected.


In ultimate analysis, then, it appears that a sensation is the
equivalent in terms of consciousness for a mode of motion of the matter
of the sensorium. But, if inquiry is pushed a stage farther, and the
question is asked, What then do we know about matter and motion? there
is but one reply possible. All that we know about motion is that it is
a name for certain changes in the relations of our visual, tactile, and
muscular sensations; and all that we know about matter is that it is
the hypothetical substance of physical phenomena—the assumption of the
existence of which is as pure a piece of metaphysical speculation as is
that of the existence of the substance of mind.

Our sensations, our pleasures, our pains, and the relations of these,
make up the sum total of the elements of positive, unquestionable
knowledge. We call a large section of these sensations and their
relations matter and motion; the rest we term mind and thinking; and
experience shows that there is a certain constant order of succession
between some of the former and some of the latter.

This is all that just metaphysical criticism leaves of the idols
set up by the spurious metaphysics of vulgar common sense. It is
consistent either with pure Materialism, or with pure Idealism, but
it is neither. For the Idealist, not content with declaring the truth
that our knowledge is limited to facts of consciousness, affirms the
wholly unprovable proposition that nothing exists beyond these and the
substance of mind. And, on the other hand, the Materialist, holding by
the truth that, for anything that appears to the contrary, material
phenomena are the causes of mental phenomena, asserts his unprovable
dogma, that material phenomena and the substance of matter are the sole
primary existences.

Strike out the propositions about which neither controversialist does
or can know anything, and there is nothing left for them to quarrel
about. Make a desert of the Unknowable, and the divine Astræa of
philosophic peace will commence her blessed reign.




XI.

EVOLUTION IN BIOLOGY.


In the former half of the eighteenth century, the term “evolution” was
introduced into biological writings, in order to denote the mode in
which some of the most eminent physiologists of that time conceived
that the generation of living things took place; in opposition to the
hypothesis advocated, in the preceding century, by Harvey in that
remarkable work[63] which would give him a claim to rank among the
founders of biological science, even had he not been the discoverer of
the circulation of the blood.

One of Harvey’s prime objects is to defend and establish, on the
basis of direct observation, the opinion already held by Aristotle;
that, in the higher animals at any rate, the formation of the new
organism by the process of generation takes place, not suddenly, by
simultaneous accretion of rudiments of all, or of the most important,
of the organs of the adult; nor by sudden metamorphosis of a formative
substance into a miniature of the whole, which subsequently grows;
but by _epigenesis_, or successive differentiation of a relatively
homogeneous rudiment into the parts and structures which are
characteristic of the adult.

  “Et primò, quidem, quoniam per _epigenesin_ sive
  partium superexorientium additamentum pullum fabricari
  certum est: quænam pars ante alias omnes exstruatur,
  et quid de illa ejusque generandi modo observandum
  veniat, dispiciemus. Ratum sane est et in ovo manifestè
  apparet quod _Aristoteles_ de perfectorum animalium
  generatione enuntiat: nimirum, non omnes partes
  simul fieri, sed ordine aliam post aliam; primùmque
  existere particulam genitalem, cujus virtute postea
  (tanquam ex principio quodam) reliquæ omnes partes
  prosiliant. Qualem in plantarum seminibus (fabis,
  putà, aut glandibus) gemmam sive apicem protuberantem
  cernimus, totius futuræ arboris principium. _Estque
  hæc particula velut filius emancipatus seorsumque
  collocatus, et principium per se vivens; unde postea
  membrorum ordo describitur; et quæcunque ad absolvendum
  animal pertinent, disponuntur._[64] Quoniam enim _nulla
  pars se ipsam generat; sed postquam generata est, se
  ipsam jam auget; ideo eam primùm oriri necesse est, quæ
  principium augendi contineat (sive enim planta, sive
  animal est, æque omnibus inest quod vim habeat vegetandi,
  sive nutriendi)_,[65] simulque reliquas omnes partes
  suo quamque ordine distinguat et formet; proindeque
  in eadem primogenita particula anima primario inest,
  sensus, motusque, et totius vitæ auctor et principium.”
  (Exercitatio 51.)

Harvey proceeds to contrast this view with that of the “Medici,” or
followers of Hippocrates and Galen, who, “badly philosophising,”
imagined that the brain, the heart, and the liver were simultaneously
first generated in the form of vesicles; and, at the same time, while
expressing his agreement with Aristotle in the principle of epigenesis,
he maintains that it is the blood which is the primal generative part,
and not, as Aristotle thought, the heart.

In the latter part of the seventeenth century, the doctrine of
epigenesis, thus advocated by Harvey, was controverted, on the ground
of direct observation, by Malpighi, who affirmed that the body of
the chick is to be seen in the egg, before the _punctum sanguineum_
makes its appearance. But, from this perfectly correct observation
a conclusion which is by no means warranted was drawn; namely, that
the chick, as a whole, really exists in the egg antecedently to
incubation; and that what happens in the course of the latter process
is no addition of new parts, “alias post alias natas,” as Harvey puts
it, but a simple expansion, or unfolding, of the organs which already
exist, though they are too small and inconspicuous to be discovered.
The weight of Malpighi’s observations therefore fell into the scale of
that doctrine which Harvey terms _metamorphosis_, in contradistinction
to epigenesis.

The views of Malpighi were warmly welcomed, on philosophical grounds,
by Leibnitz,[66] who found in them a support to his hypothesis
of monads, and by Malebranche;[67] while, in the middle of the
eighteenth century, not only speculative considerations, but a
great number of new and interesting observations on the phenomena
of generation, led the ingenious Bonnet, and Haller,[68] the first
physiologist of the age, to adopt, advocate, and extend them.

Bonnet affirms that, before fecundation, the hen’s egg contains an
excessively minute but complete chick; and that fecundation and
incubation simply cause this germ to absorb nutritious matters, which
are deposited in the interstices of the elementary structures of which
the miniature chick, or germ, is made up. The consequence of this
intussusceptive growth is the “development” or “evolution” of the germ
into the visible bird. Thus an organised individual (_tout organisé_)
“is a composite body consisting of the original, or _elementary_,
parts and of the matters which have been associated with them by the
aid of nutrition;” so that, if these matters could be extracted from
the individual (_tout_), it would, so to speak, become concentrated
in a point, and would thus be restored to its primitive condition of
a _germ_; “just as by extracting from a bone the calcareous substance
which is the source of its hardness, it is reduced to its primitive
state of gristle or membrane.”[69]

“Evolution” and “development” are, for Bonnet, synonymous terms; and
since by “evolution” he means simply the expansion of that which was
invisible into visibility, he was naturally led to the conclusion,
at which Leibnitz had arrived by a different line of reasoning, that
no such thing as generation, in the proper sense of the word, exists
in nature. The growth of an organic being is simply a process of
enlargement, as a particle of dry gelatine may be swelled up by the
intussusception of water; its death is a shrinkage, such as the swelled
jelly might undergo on desiccation. Nothing really new is produced
in the living world, but the germs which develop have existed since
the beginning of things; and nothing really dies, but, when what we
call death takes place, the living thing shrinks back into its germ
state.[70]

The two parts of Bonnet’s hypothesis, namely, the doctrine that all
living things proceed from pre-existing germs, and that these contain,
one inclosed within the other, the germs of all future living things,
which is the hypothesis of “_emboîtement_;” and the doctrine that every
germ contains in miniature all the organs of the adult, which is the
hypothesis of evolution or development, in the primary senses of these
words, must be carefully distinguished. In fact, while holding firmly
by the former, Bonnet more or less modified the latter in his later
writings, and, at length, he admits that a “germ” need not be an actual
miniature of the organism; but that it may be merely an “original
preformation” capable of producing the latter.[71]

But, thus defined, the germ is neither more nor less than the
“particula genitalis” of Aristotle, or the “primordium vegetale” or
“ovum” of Harvey; and the “evolution” of such a germ would not be
distinguishable from “epigenesis.”

Supported by the great authority of Haller, the doctrine of evolution,
or development, prevailed throughout the whole of the eighteenth
century, and Cuvier appears to have substantially adopted Bonnet’s
later views, though probably he would not have gone all lengths in
the direction of “emboîtement.” In a well-known note to Laurillards’
“Éloge,” prefixed to the last edition of the “Ossemens fossiles,” the
“radical de l’être” is much the same thing as Aristotle’s “particula
genitalis” and Harvey’s “ovum.”[72]

Bonnet’s eminent contemporary, Buffon, held nearly the same views
with respect to the nature of the germ, and expresses them even more
confidently.[73]

  “Ceux qui ont cru que le cœur étoit le premier formé,
  se sont trompés; ceux qui disent que c’est le sang se
  trompent aussi: tout est formé en même temps. Si l’on ne
  consulte que l’observation, le poulet se voit dans l’œuf
  avant qui’il ait été couvé.”

  “J’ai ouvert une grande quantité d’œufs à differens temps
  avant et après l’incubation, et je me suis convaincu par
  mes yeux que le poulet existe en entier dans le milieu
  de la cicatricule au moment qu’il sort du corps de la
  poule.”[74]

The “moule intérieur” of Buffon is the aggregate of elementary
parts which constitute the individual, and is thus the equivalent
of Bonnet’s germ,[75] as defined in the passage cited above. But
Buffon further imagined that innumerable “molecules organiques” are
dispersed throughout the world, and that alimentation consists in the
appropriation by the parts of an organism of those molecules which
are analogous to them. Growth, therefore, was, on this hypothesis, a
process partly of simple evolution, and partly of what has been termed
“syngenesis.” Buffon’s opinion is, in fact, a sort of combination of
views, essentially similar to those of Bonnet, with others, somewhat
similar to those of the “Medici” whom Harvey condemns. The “molecules
organiques” are physical equivalents of Leibnitz’s “monads.”

It is a striking example of the difficulty of getting people to use
their own powers of investigation accurately, that this form of the
doctrine of evolution should have held its ground so long; for it was
thoroughly and completely exploded, not long after its enunciation, by
Caspar Friederich Wolff, who in his “Theoria Generationis,” published
in 1759, placed the opposite theory of epigenesis upon the secure
foundation of fact, from which it has never been displaced. But Wolff
had no immediate successors. The school of Cuvier was lamentably
deficient in embryologists; and it was only in the course of the
first thirty years of the present century, that Prévost and Dumas in
France, and, later on, Döllinger, Pander, Von Bär, Rathke, and Remak
in Germany, founded modern embryology; while, at the same time, they
proved the utter incompatibility of the hypothesis of evolution, as
formulated by Bonnet and Haller, with easily demonstrable facts.

Nevertheless, though the conceptions originally denoted by “evolution”
and “development” were shown to be untenable, the words retained
their application to the process by which the embryos of living
beings gradually make their appearance; and the terms “Development,”
“Entwickelung,” and “Evolutio,” are now indiscriminately used for
the series of genetic changes exhibited by living beings, by writers
who would emphatically deny that “Development” or “Entwickelung” or
“Evolutio,” in the sense in which these words were usually employed by
Bonnet or by Haller, ever occurs.

Evolution, or development, is, in fact, at present employed in biology
as a general name for the history of the steps by which any living
being has acquired the morphological and the physiological characters
which distinguish it. As civil history may be divided into biography,
which is the history of individuals, and universal history, which is
the history of the human race, so evolution falls naturally into two
categories,—the evolution of the individual, and the evolution of the
sum of living beings. It will be convenient to deal with the modern
doctrine of evolution under these two heads.


I. _The Evolution of the Individual._

No exception is, at this time, known to the general law, established
upon an immense multitude of direct observations, that every living
thing is evolved from a particle of matter in which no trace of the
distinctive characters of the adult form of that living thing is
discernible. This particle is termed a _germ_. Harvey[76] says—

  “Omnibus viventibus primordium insit, ex quo et a quo
  proveniant. Liceat hoc nobis _primordium vegetale_
  nominare; nempe substantiam quandam corpoream vitam
  habentem potentiâ; vel quoddam per se existens, quod
  aptum sit, in vegetativam formam, ab interno principio
  operante, mutari. Quale nempe primordium, ovum est et
  plantarum semen; tale etiam viviparorum conceptus,
  et insectorum _vermis_ ab Aristotele dictus: diversa
  scilicet diversorum viventium primordia.”

The definition of a germ as “matter potentially alive, and having
within itself the tendency to assume a definite living form,” appears
to meet all the requirements of modern science. For, notwithstanding it
might be justly questioned whether a germ is not merely potentially,
but rather actually, alive, though its vital manifestations are reduced
to a minimum, the term “potential” may fairly be used in a sense broad
enough to escape the objection. And the qualification of “potential”
has the advantage of reminding us that the great characteristic of
the germ is not so much what it is, but what it may, under suitable
conditions, become. Harvey shared the belief of Aristotle—whose
writings he so often quotes, and of whom he speaks as his precursor and
model, with the generous respect with which one genuine worker should
regard another—that such germs may arise by a process of “equivocal
generation” out of not-living matter; and the aphorism so commonly
ascribed to him, “_omne vivum ex ovo_,” and which is indeed a fair
summary of his reiterated assertions, though incessantly employed
against the modern advocates of spontaneous generation, can be honestly
so used only by those who have never read a score of pages of the
“Exercitationes.” Harvey, in fact, believed as implicitly as Aristotle
did in the equivocal generation of the lower animals. But, while the
course of modern investigation has only brought out into greater
prominence the accuracy of Harvey’s conception of the nature and mode
of development of germs, it has as distinctly tended to disprove the
occurrence of equivocal generation, or abiogenesis, in the present
course of nature. In the immense majority of both plants and animals,
it is certain that the germ is not merely a body in which life is
dormant or potential, but that it is itself simply a detached portion
of the substance of a pre-existing living body; and the evidence has
yet to be adduced which will satisfy any cautious reasoner that “omne
vivum ex vivo” is not as well-established a law of the existing course
of nature as “omne vivum ex ovo.”

In all instances which have yet been investigated, the substance of
this germ has a peculiar chemical composition, consisting of at fewest
four elementary bodies, viz. carbon, hydrogen, oxygen, and nitrogen,
united into the ill-defined compound known as protein, and associated
with much water, and very generally, if not always, with sulphur and
phosphorus in minute proportions. Moreover, up to the present time,
protein is known only as a product and constituent of living matter.
Again, a true germ is either devoid of any structure discernible by
optical means, or, at most, it is a simple nucleated cell.[77]

In all cases, the process of evolution consists in a succession of
changes of the form, structure, and functions of the germ, by which
it passes, step by step, from an extreme simplicity, or relative
homogeneity, of visible structure, to a greater or less degree
of complexity or heterogeneity; and the course of progressive
differentiation is usually accompanied by growth, which is effected by
intussusception. This intussusception, however, is a very different
process from that imagined either by Buffon, or by Bonnet. The
substance by the addition of which the germ is enlarged is, in no
case, simply absorbed ready-made from the not-living world and packed
between the elementary constituents of the germ, as Bonnet imagined;
still less does it consist of the “molecules organiques” of Buffon. The
new material is, in great measure, not only absorbed but assimilated,
so that it becomes part and parcel of the molecular structure of
the living body into which it enters. And, so far from the fully
developed organism being simply the germ _plus_ the nutriment which
it has absorbed, it is probable that the adult contains neither in
form, nor in substance, more than an inappreciable fraction of the
constituents of the germ, and that it is almost, if not wholly, made
up of assimilated and metamorphosed nutriment. In the great majority of
cases, at any rate, the full-grown organism becomes what it is by the
absorption of not-living matter, and its conversion into living matter
of a specific type. As Harvey says (Ex. 45), all parts of the body are
nourished “ab eodem succo alibili, aliter aliterque cambiato,” “ut
plantæ omnes ex eodem communi nutrimento (sive rore seu terræ humore).”

In all animals and plants, above the lowest, the germ is a nucleated
cell, using that term in its broadest sense; and the first step in the
process of the evolution of the individual is the division of this
cell into two or more portions. The process of division is repeated,
until the organism, from being unicellular, becomes multicellular.
The single cell becomes a cell-aggregate; and it is to the growth and
metamorphosis of the cells of the cell-aggregate thus produced, that
all the organs and tissues of the adult owe their origin.

In certain animals belonging to every one of the chief groups into
which the _Metazoa_ are divisible, the cells of the cell-aggregate
which results from the process of yelk-division, and which is termed
a _morula_, diverge from one another in such a manner as to give rise
to a central space, around which they dispose themselves as a coat or
envelope; and thus the morula becomes a vesicle filled with fluid,
the _planula_. The wall of the planula is next pushed in on one side,
or invaginated, whereby it is converted into a double-walled sac
with an opening, the _blastopore_, which leads into the cavity lined
by the inner wall. This cavity is the primitive alimentary cavity or
_archenteron_; the inner, or invaginated, layer is the _hypoblast_,
the outer the _epiblast_; and the embryo, in this stage, is termed
a _gastrula_. In all the higher animals, a layer of cells makes its
appearance between the hypoblast and the epiblast, and is termed the
_mesoblast_. In the further course of development, the epiblast becomes
the ectoderm or epidermic layer of the body; the hypoblast becomes
the epithelium of the middle portion of the alimentary canal; and the
mesoblast gives rise to all the other tissues, except the central
nervous system, which originates from an ingrowth of the epiblast.

With more or less modification in detail, the embryo has been observed
to pass through these successive evolutional stages in sundry Sponges,
Cœlenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks,
and Vertebrates; and there are valid reasons for the belief, that
all animals of higher organisation than the _Protozoa_ agree in the
general character of the early stages of their individual evolution.
Each, starting from the condition of a simple nucleated cell, becomes
a cell-aggregate; and this passes through a condition which represents
the gastrula stage, before taking on the features distinctive of the
group to which it belongs. Stated in this form, the “gastræa theory” of
Haeckel appears to the present writer to be one of the most important
and best founded of recent generalisations. So far as individual
plants and animals are concerned, therefore, evolution is not a
speculation but a fact; and it takes place by epigenesis.

  “Animal ... per _epigenesin_ procreatur, materiam simul
  attrahit, parat, concoquit, et eâdem utitur; formatur
  simul et augetur ... primum futuri corporis concrementum
  ... prout augetur, dividitur sensim et distinguitur in
  partes, non simul omnes, sed alias post alias natas, et
  ordine quasque suo emergentes.”[78]

In these words, by the divination of genius, Harvey, in the seventeenth
century, summed up the outcome of the work of all those who, with
appliances he could not dream of, are continuing his labours in the
nineteenth century.

Nevertheless, though the doctrine of epigenesis, as understood by
Harvey, has definitively triumphed over the doctrine of evolution,
as understood by his opponents of the eighteenth century, it is not
impossible that, when the analysis of the process of development is
carried still farther, and the origin of the molecular components of
the physically gross, though sensibly minute, bodies which we term
germs is traced, the theory of development will approach more nearly
to metamorphosis than to epigenesis. Harvey thought that impregnation
influenced the female organism as a contagion; and that the blood,
which he conceived to be the first rudiment of the germ, arose in
the clear fluid of the “colliquamentum” of the ovum by a process of
concrescence, as a sort of living precipitate. We now know, on the
contrary, that the female germ or ovum, in all the higher animals
and plants, is a body which possesses the structure of a nucleated
cell; that impregnation consists in the fusion of the substance[79]
of another more or less modified nucleated cell, the male germ, with
the ovum; and that the structural components of the body of the
embryo are all derived, by a process of division, from the coalesced
male and female germs. Hence it is conceivable, and indeed probable,
that every part of the adult contains molecules, derived both from
the male and from the female parent; and that, regarded as a mass
of molecules, the entire organism may be compared to a web of which
the warp is derived from the female and the woof from the male. And
each of these may constitute one individuality, in the same sense
as the whole organism is one individual, although the matter of the
organism has been constantly changing. The primitive male and female
molecules may play the part of Buffon’s “moules organiques,” and
mould the assimilated nutriment, each according to its own type, into
innumerable new molecules. From this point of view the process, which,
in its superficial aspect, is epigenesis, appears in essence, to be
evolution, in the modified sense adopted in Bonnet’s later writings;
and development is merely the expansion of a potential organism or
“original preformation” according to fixed laws.


II. _The Evolution of the Sum of Living Beings._

The notion that all the kinds of animals and plants may have come into
existence by the growth and modification of primordial germs is as old
as speculative thought; but the modern scientific form of the doctrine
can be traced historically to the influence of several converging lines
of philosophical speculation and of physical observation, none of which
go farther back than the seventeenth century. These are:—

1. The enunciation by Descartes of the conception that the physical
universe, whether living or not living, is a mechanism, and that, as
such, it is explicable on physical principles.

2. The observation of the gradations of structure, from extreme
simplicity to very great complexity, presented by living things, and of
the relation of these graduated forms to one another.

3. The observation of the existence of an analogy between the series
of gradations presented by the species which compose any great group
of animals or plants, and the series of embryonic conditions of the
highest members of that group.

4. The observation that large groups of species of widely different
habits present the same fundamental plan of structure; and that parts
of the same animal or plant, the functions of which are very different,
likewise exhibit modifications of a common plan.

5. The observation of the existence of structures, in a rudimentary
and apparently useless condition, in one species of a group, which are
fully developed and have definite functions in other species of the
same group.

6. The observation of the effects of varying conditions in modifying
living organisms.

7. The observation of the facts of geographical distribution.

8. The observation of the facts of the geological succession of the
forms of life.


1. Notwithstanding the elaborate disguise which fear of the powers that
were led Descartes to throw over his real opinions, it is impossible to
read the “Principes de la Philosophie” without acquiring the conviction
that this great philosopher held that the physical world and all things
in it, whether living or not living, have originated by a process of
evolution, due to the continuous operation of purely physical causes,
out of a primitive relatively formless matter.[80]

The following passage is especially instructive:—

  “Et tant s’en faut que je veuille que l’on croie toutes
  les choses que j’écrirai, que même je pretends en
  proposer ici quelques unes que je crois absolument être
  fausses; à savoir, je ne doute point que le monde n’ait
  été créé au commencement avec autant de perfection qu’il
  en a; en sorte que le soleil, la terre, la lune, et
  les étoiles ont été dès lors; et que la terre n’a pas
  eu seulement en soi les semences des plantes, mais que
  les plantes même en ont couvert une partie; et qu’Adam
  et Eve n’ont pas été créés enfans mais en âge d’hommes
  parfaits. La religion chrétienne veut que nous le croyons
  ainsi, et la raison naturelle nous persuade entièrement
  cette vérité; car si nous considérons la toute puissance
  de Dieu, nous devons juger que tout ce qu’il a fait a
  eu dès le commencement toute la perfection qu’il devoit
  avoir. Mais néanmoins, comme on connôitroit beaucoup
  mieux quelle a été la nature d’Adam et celle des arbres
  de Paradis si on avoit examiné comment les enfants se
  forment peu à peu dans le ventre de leurs mères et
  comment les plantes sortent de leurs semences, que si on
  avoit seulement considéré quels ils ont été quand Dieu
  les a créés: tout de même, nous ferons mieux entendre
  quelle est généralement la nature de toutes les choses
  qui sont au monde si nous pouvons imaginer quelques
  principes qui soient fort intelligibles et fort simples,
  desquels nous puissions voir clairement que les astres et
  la terre et enfin tout ce monde visible auroit pu être
  produit ainsi que de quelques semences (bien que nous
  sachions qu’il n’a pas été produit en cette façon) que si
  nous la decrivions seulement comme il est, ou bien comme
  nous croyons qu’il a été créé. Et parceque je pense avoir
  trouvé des principes qui sont tels, je tacherai ici de
  les expliquer.”[81]

If we read between the lines of this singular exhibition of force of
one kind and weakness of another, it is clear that Descartes believed
that he had divined the mode in which the physical universe had been
evolved; and the “Traité de l’homme,” and the essay “Sur les Passions”
afford abundant additional evidence that he sought for, and thought
he had found, an explanation of the phenomena of physical life by
deduction from purely physical laws.

Spinoza abounds in the same sense, and is as usual perfectly candid—

  “Naturæ leges et regulæ, secundum quas omnia fiunt et
  ex unis formis in alias mutantur, sunt ubique et semper
  eadem.”[82]

Leibnitz’s doctrine of continuity necessarily led him in the same
direction; and, of the infinite multitude of monads with which he
peopled the world, each is supposed to be the focus of an endless
process of evolution and involution. In the “Protogæa,” xxvi., Leibnitz
distinctly suggests the mutability of species—

  “Alii mirantur in saxis passim species videri quas vel
  in orbe cognito, vel saltem in vicinis locis frustra
  quæras. Ita “Cornua Ammonis,” quæ ex nautilorum numero
  habeantur, passim et forma et magnitudine (nam et pedali
  diametro aliquando reperiuntur) ab omnibus illis naturis
  discrepare dicunt, quas præbet mare. Sed quis absconditos
  ejus recessus aut subterraneas abyssos pervestigavit?
  quam multa nobis animalia antea ignota offert novus
  orbis? Et credibile est per magnas illas conversiones
  etiam animalium species plurimum immutatas.”

Thus, in the end of the seventeenth century, the seed was sown which
has, at intervals, brought forth recurrent crops of evolutional
hypotheses, based, more or less completely, on general reasonings.

Among the earliest of these speculations is that put forward by Benoit
de Maillet in his “Telliamed,” which, though printed in 1735, was
not published until twenty-three years later. Considering that this
book was written before the time of Haller, or Bonnet, or Linnæus,
or Hutton, it surely deserves more respectful consideration than it
usually receives. For De Maillet not only has a definite conception
of the plasticity of living things, and of the production of existing
species by the modification of their predecessors; but he clearly
apprehends the cardinal maxim of modern geological science, that the
explanation of the structure of the globe is to be sought in the
deductive application to geological phenomena of the principles
established inductively by the study of the present course of nature.
Somewhat later, Maupertuis[83] suggested a curious hypothesis as to
the causes of variation, which he thinks may be sufficient to account
for the origin of all animals from a single pair. Robinet[84] followed
out much the same line of thought as De Maillet, but less soberly; and
Bonnet’s speculations in the “Palingénésie,” which appeared in 1769,
have already been mentioned. Buffon (1753-1778), at first a partisan
of the absolute immutability of species, subsequently appears to have
believed that larger or smaller groups of species have been produced by
the modification of a primitive stock; but he contributed nothing to
the general doctrine of evolution.

Erasmus Darwin (“Zoonomia,” 1794), though a zealous evolutionist, can
hardly be said to have made any real advance on his predecessors;
and, notwithstanding that Goethe (1791-4) had the advantage of a
wide knowledge of morphological facts, and a true insight into their
signification, while he threw all the power of a great poet into
the expression of his conceptions, it may be questioned whether he
supplied the doctrine of evolution with a firmer scientific basis
than it already possessed. Moreover, whatever the value of Goethe’s
labours in that field, they were not published before 1820, long after
evolutionism had taken a new departure from the works of Treviranus
and Lamarck—the first of its advocates who were equipped for their
task with the needful large and accurate knowledge of the phenomena of
life, as a whole. It is remarkable that each of these writers seems
to have been led, independently and contemporaneously, to invent the
same name of “Biology” for the science of the phenomena of life; and
thus, following Buffon, to have recognised the essential unity of these
phenomena, and their contradistinction from those of inanimate nature.
And it is hard to say whether Lamarck or Treviranus has the priority in
propounding the main thesis of the doctrine of evolution; for though
the first volume of Treviranus’s “Biologie” appeared only in 1802, he
says, in the preface to his later work, the “Erscheinungen und Gesetze
des organischen Lebens,” dated 1831, that he wrote the first volume of
the “Biologie” “nearly five-and-thirty years ago,” or about 1796.

Now, in 1794, there is evidence that Lamarck held doctrines which
present a striking contrast to those which are to be found in the
“Philosophic Zoologique,” as the following passages show:—

  “685. Quoique mon unique objet dans cet article n’ait été
  que de traiter de la cause physique de l’entretien de la
  vie des êtres organiques, malgré cela j’ai osé avancer
  en débutant, que l’existence de ces êtres étonnants
  n’appartiennent nullement à la nature; que tout ce qu’on
  peut entendre par le mot _nature_, ne pouvoit donner la
  vie, c’est-à-dire, que toutes les qualités de la matière,
  jointes à toutes les circonstances possibles, et même à
  l’activité répandue dans l’univers, ne pouvaient point
  produire un être muni du mouvement organique, capable de
  reproduire son semblable, et sujet à la mort.

  “686. Tous les individus de cette nature, qui existent,
  proviennent d’individus semblables qui tous ensemble
  constituent l’espèce entière. Or, je crois qu’il est
  aussi impossible à l’homme de connôitre la cause physique
  du premier individu de chaque espèce, que d’assigner
  aussi physiquement la cause de l’existence de la
  matière ou de l’univers entier. C’est au moins ce que
  le résultat de mes connaissances et de mes réflexions
  me portent à penser. S’il existe beaucoup de variétés
  produites par l’effet des circonstances, ces variétés ne
  dénaturent point les espèces; mais on se trompe, sans
  doute souvent, en indiquant comme espèce, ce qui n’est
  que variété; et alors je sens que cette erreur peut tirer
  à conséquence dans les raisonnements que l’on fait sur
  cette matière.”[85]

The first three volumes of Treviranus’s “Biologie,” which contain
his general views of evolution, appeared between 1802 and 1805. The
“Recherches sur l’organisation des corps vivants,” in which the
outlines of Lamarck’s doctrines are given, was published in 1802; but
the full development of his views, in the “Philosophie Zoologique,” did
not take place until 1809.

The “Biologie” and the “Philosophie Zoologique” are both very
remarkable productions, and are still worthy of attentive study, but
they fell upon evil times. The vast authority of Cuvier was employed
in support of the traditionally respectable hypotheses of special
creation and of catastrophism; and the wild speculations of the
“Discours sur les Révolutions de la Surface du Globe” were held to be
models of sound scientific thinking, while the really much more sober
and philosophical hypotheses of the “Hydrogeologie” were scouted. For
many years it was the fashion to speak of Lamarck with ridicule, while
Treviranus was altogether ignored.

Nevertheless, the work had been done. The conception of evolution
was henceforward irrepressible, and it incessantly reappears, in one
shape or another,[86] up to the year 1858, when Mr. Darwin and Mr.
Wallace published their “Theory of Natural Selection.” The “Origin of
Species” appeared in 1859; and it is within the knowledge of all whose
memories go back to that time, that, henceforward, the doctrine of
evolution has assumed a position and acquired an importance which it
never before possessed. In the “Origin of Species,” and in his other
numerous and important contributions to the solution of the problem of
biological evolution, Mr. Darwin confines himself to the discussion of
the causes which have brought about the present condition of living
matter, assuming such matter to have once come into existence. On the
other hand, Mr. Spencer[87] and Professor Haeckel[88] have dealt with
the whole problem of evolution. The profound and vigorous writings of
Mr. Spencer embody the spirit of Descartes in the knowledge of our own
day, and may be regarded as the “Principes de la Philosophie” of the
nineteenth century; while, whatever hesitation may not unfrequently
be felt by less daring minds, in following Haeckel in many of his
speculations, his attempt to systematise the doctrine of evolution and
to exhibit its influence as the central thought of modern biology,
cannot fail to have a far-reaching influence on the progress of science.

If we seek for the reason of the difference between the scientific
position of the doctrine of evolution a century ago, and that which it
occupies now, we shall find it in the great accumulation of facts, the
several classes of which have been enumerated above, under the second
to the eighth heads. For those which are grouped under the second to
the seventh of these classes, respectively, have a clear significance
on the hypothesis of evolution, while they are unintelligible if that
hypothesis be denied. And those of the eighth group are not only
unintelligible without the assumption of evolution, but can be proved
never to be discordant with that hypothesis, while, in some cases,
they are exactly such as the hypothesis requires. The demonstration of
these assertions would require a volume, but the general nature of the
evidence on which they rest may be briefly indicated.

2. The accurate investigation of the lowest forms of animal life,
commenced by Leeuwenhoek and Swammerdam, and continued by the
remarkable labours of Reaumur, Trembley, Bonnet, and a host of other
observers, in the latter part of the seventeenth and the first half
of the eighteenth centuries, drew the attention of biologists to the
gradation in the complexity of organisation which is presented by
living beings, and culminated in the doctrine of the “échelle des
êtres,” so powerfully and clearly stated by Bonnet; and, before him,
adumbrated by Locke and by Leibnitz. In the then state of knowledge, it
appeared that all the species of animals and plants could be arranged
in one series; in such a manner that, by insensible gradations, the
mineral passed into the plant, the plant into the polype, the polype
into the worm, and so, through gradually higher forms of life, to man,
at the summit of the animated world.

But, as knowledge advanced, this conception ceased to be tenable in
the crude form in which it was first put forward. Taking into account
existing animals and plants alone, it became obvious that they fell
into groups which were more or less sharply separated from one another;
and, moreover, that even the species of a genus can hardly ever be
arranged in linear series. Their natural resemblances and differences
are only to be expressed by disposing them as if they were branches
springing from a common hypothetical centre.

Lamarck, while affirming the verbal proposition that animals form a
single series, was forced by his vast acquaintance with the details
of zoology to limit the assertion to such a series as may be formed
out of the abstractions constituted by the common characters of each
group.[89]

Cuvier on anatomical, and Von Baer on embryological grounds, made the
further step of proving that, even in this limited sense, animals
cannot be arranged in a single series, but that there are several
distinct plans of organisation to be observed among them, no one of
which, in its highest and most complicated modification, leads to any
of the others.

The conclusions enunciated by Cuvier and Von Baer have been confirmed,
in principle, by all subsequent research into the structure of animals
and plants. But the effect of the adoption of these conclusions has
been rather to substitute a new metaphor for that of Bonnet than to
abolish the conception expressed by it. Instead of regarding living
things as capable of arrangement in one series like the steps of a
ladder, the results of modern investigation compel us to dispose them
as if they were the twigs and branches of a tree. The ends of the twigs
represent individuals, the smallest groups of twigs species, larger
groups genera, and so on, until we arrive at the source of all these
ramifications of the main branch, which is represented by a common
plan of structure. At the present moment, it is impossible to draw up
any definition, based on broad anatomical or developmental characters,
by which any one of Cuvier’s great groups shall be separated from all
the rest. On the contrary, the lower members of each tend to converge
towards the lower members of all the others. The same may be said of
the vegetable world. The apparently clear distinction between flowering
and flowerless plants has been broken down by the series of gradations
between the two exhibited by the _Lycopodiaceæ_, _Rhizocarpeæ_, and
_Gymnospermeæ_. The groups of _Fungi_, _Lichenes_, and _Algæ_ have
completely run into one another, and, when the lowest forms of each are
alone considered, even the animal and vegetable kingdoms cease to have
a definite frontier.

If it is permissible to speak of the relations of living forms to one
another metaphorically, the similitude chosen must undoubtedly be
that of a common root, whence two main trunks, one representing the
vegetable and one the animal world, spring; and, each dividing into a
few main branches, these subdivide into multitudes of branchlets and
these into smaller groups of twigs.

As Lamarck has well said—[90]

  “Il n’y a que ceux qui se sont longtemps et fortement
  occupés de la détermination des espèces, et qui ont
  consulté de riches collections, qui peuvent savoir
  jusqu’à quel point les _espèces_, parmi les corps vivants
  se fondent les unes dans les autres, et qui ont pu se
  convaincre que, dans les parties où nous voyons des
  _espèces_ isolès, cela n’est ainsi que parcequ’il nous
  en manque d’autres qui en sont plus voisines et que nous
  n’avons pas encore recueillies.

  “Je ne veux pas dire pour cela que les animaux qui
  existent forment une série très-simple et partout
  également nuancée; mais je dis qu’ils forment une série
  rameuse, irréguliérement graduée et qui n’a point de
  discontinuité dans ses parties, ou qui, du moins, n’en
  a toujours pas eu, s’il est vrai que, par suite de
  quelques espèces perdues, il s’en trouve quelque part.
  Il en resulte que les _espèces_ qui terminent chaque
  rameau de la série générale tiennent, au moins d’un
  côté, à d’autres espèces voisines qui se nuancent avec
  elles. Voilà ce que l’état bien connu des choses me
  met maintenant à portée de demontrer. Je n’ai besoin
  d’aucune hypothèse ni d’aucune supposition pour cela:
  j’en atteste tous les naturalistes observateurs.”

3. In a remarkable essay[91] Meckel remarks—

  “There is no good physiologist who has not been struck by
  the observation that the original form of all organisms
  is one and the same, and that out of this one form, all,
  the lowest as well as the highest, are developed in such
  a manner that the latter pass through the permanent forms
  of the former as transitory stages. Aristotle, Haller,
  Harvey, Kielmeyer, Autenrieth, and many others, have
  either made this observation incidentally, or, especially
  the latter, have drawn particular attention to it, and
  drawn therefrom results of permanent importance for
  physiology.”

Meckel proceeds to exemplify the thesis, that the lower forms of
animals represent stages in the course of the development of the
higher, with a large series of illustrations.

After comparing the Salamanders and the perenni-branchiate _Urodela_
with the Tadpoles and the Frogs, and enunciating the law that the more
highly any animal is organised the more quickly does it pass through
the lower stages, Meckel goes on to say—

  “From these lowest Vertebrata to the highest, and to
  the highest forms among these, the comparison between
  the embryonic conditions of the higher animals and the
  adult states of the lower can be more completely and
  thoroughly instituted than if the survey is extended to
  the Invertebrata, inasmuch as the latter are in many
  respects constructed upon an altogether too dissimilar
  type; indeed they often differ from one another far more
  than the lowest vertebrate does from the highest mammal;
  yet the following pages will show that the comparison
  may also be extended to them with interest. In fact,
  there is a period when, as Aristotle long ago said, the
  embryo of the highest animal has the form of a mere worm;
  and, devoid of internal and external organisation, is
  merely an almost structureless lump of polype-substance.
  Notwithstanding the origin of organs, it still for a
  certain time, by reason of its want of an internal bony
  skeleton, remains worm and mollusk, and only later enters
  into the series of the Vertebrata, although traces of the
  vertebral column even in the earliest periods testify its
  claim to a place in that series.”—_Op. cit._ pp. 4, 5.

If Meckel’s proposition is so far qualified, that the comparison of
adult with embryonic forms is restricted within the limits of one type
of organisation; and, if it is further recollected that the resemblance
between the permanent lower form and the embryonic stage of a higher
form is not special but general, it is in entire accordance with modern
embryology; although there is no branch of biology which has grown so
largely, and improved its methods so much, since Meckel’s time, as
this. In its original form, the doctrine of “arrest of development,”
as advocated by Geoffroy Saint-Hilaire and Serres, was no doubt an
over-statement of the case. It is not true, for example, that a fish
is a reptile arrested in its development, or that a reptile was ever
a fish: but it is true that the reptile embryo, at one stage of its
development, is an organism which, if it had an independent existence,
must be classified among fishes; and all the organs of the reptile
pass, in the course of their development, through conditions which are
closely analogous to those which are permanent in some fishes.

4. That branch of biology which is termed Morphology is a commentary
upon, and expansion of, the proposition that widely different animals
or plants, and widely different parts of animals or plants, are
constructed upon the same plan. From the rough comparison of the
skeleton of a bird with that of a man by Belon, in the sixteenth
century (to go no farther back), down to the theory of the limbs
and the theory of the skull at the present day; or, from the first
demonstration of the homologies of the parts of a flower by C. F.
Wolff, to the present elaborate analysis of the floral organs,
morphology exhibits a continual advance towards the demonstration of a
fundamental unity among the seeming diversities of living structures.
And this demonstration has been completed by the final establishment
of the cell theory, which involves the admission of a primitive
conformity, not only of all the elementary structures in animals and
plants respectively, but of those in the one of these great divisions
of living things with those in the other. No _à priori_ difficulty can
be said to stand in the way of evolution, when it can be shown that
all animals and all plants proceed by modes of development, which are
similar in principle, from a fundamental protoplasmic material.

5. The innumerable cases of structures, which are rudimentary and
apparently useless, in species, the close allies of which possess
well developed and functionally important homologous structures, are
readily intelligible on the theory of evolution, while it is hard to
conceive their _raison d’être_ on any other hypothesis. However, a
cautious reasoner will probably rather explain such cases deductively
from the doctrine of evolution than endeavour to support the doctrine
of evolution by them. For it is almost impossible to prove that any
structure, however rudimentary, is useless—that is to say, that it
plays no part whatever in the economy; and, if it is in the slightest
degree useful, there is no reason why, on the hypothesis of direct
creation, it should not have been created. Nevertheless, double-edged
as is the argument from rudimentary organs, there is probably none
which has produced a greater effect in promoting the general acceptance
of the theory of evolution.

6. The older advocates of evolution sought for the causes of the
process exclusively in the influence of varying conditions, such
as climate and station, or hybridisation, upon living forms. Even
Treviranus has got no farther than this point. Lamarck introduced
the conception of the action of an animal on itself as a factor in
producing modification. Starting from the well-known fact that the
habitual use of a limb tends to develop the muscles of the limb, and to
produce a greater and greater facility in using it, he made the general
assumption that the effort of an animal to exert an organ in a given
direction tends to develop the organ in that direction. But a little
consideration showed that, though Lamarck had seized what, as far as
it goes, is a true cause of modification, it is a cause the actual
effects of which are wholly inadequate to account for any considerable
modification in animals, and which can have no influence at all in the
vegetable world; and probably nothing contributed so much to discredit
evolution, in the early part of this century, as the floods of easy
ridicule which were poured upon this part of Lamarck’s speculation.
The theory of natural selection, or survival of the fittest, was
suggested by Wells in 1813, and further elaborated by Matthew in 1831.
But the pregnant suggestions of these writers remained practically
unnoticed and forgotten, until the theory was independently devised
and promulgated by Darwin and Wallace in 1858, and the effect of its
publication was immediate and profound.

Those who were unwilling to accept evolution, without better grounds
than such as are offered by Lamarck, or the author of that particularly
unsatisfactory book, the “Vestiges of the Natural History of the
Creation,” and who therefore preferred to suspend their judgment on the
question, found, in the principle of selective breeding, pursued in all
its applications with marvellous knowledge and skill by Mr. Darwin,
a valid explanation of the occurrence of varieties and races; and
they saw clearly that, if the explanation would apply to species, it
would not only solve the problem of their evolution, but that it would
account for the facts of teleology, as well as for those of morphology;
and for the persistence of some forms of life unchanged through long
epochs of time, while others undergo comparatively rapid metamorphosis.

How far “natural selection” suffices for the production of species
remains to be seen. Few can doubt that, if not the whole cause, it is a
very important factor in that operation; and that it must play a great
part in the sorting out of varieties into those which are transitory
and those which are permanent.

But the causes and conditions of variation have yet to be thoroughly
explored; and the importance of natural selection will not be impaired,
even if further inquiries should prove that variability is definite,
and is determined in certain directions rather than in others, by
conditions inherent in that which varies. It is quite conceivable that
every species tends to produce varieties of a limited number and kind,
and that the effect of natural selection is to favour the development
of some of these, while it opposes the development of others along
their predetermined lines of modification.

7. No truths brought to light by biological investigation were better
calculated to inspire distrust of the dogmas intruded upon science
in the name of theology, than those which relate to the distribution
of animals and plants on the surface of the earth. Very skilful
accommodation was needful, if the limitation of sloths to South
America, and of the ornithorhynchus to Australia, was to be reconciled
with the literal interpretation of the history of the deluge; and,
with the establishment of the existence of distinct provinces of
distribution, any serious belief in the peopling of the world by
migration from Mount Ararat came to an end.

Under these circumstances, only one alternative was left for those
who denied the occurrence of evolution—namely, the supposition that
the characteristic animals and plants of each great province were
created, as such, within the limits in which we find them. And as the
hypothesis of “specific centres,” thus formulated, was heterodox from
the theological point of view, and unintelligible under its scientific
aspect, it may be passed over without further notice, as a phase of
transition from the creational to the evolutional hypothesis.

8. In fact, the strongest and most conclusive arguments in favour of
evolution are those which are based upon the facts of geographical,
taken in conjunction with those of geological, distribution.

Both Mr. Darwin and Mr. Wallace lay great stress on the close relation
which obtains between the existing fauna of any region and that of
the immediately antecedent geological epoch in the same region; and
rightly, for it is in truth inconceivable that there should be no
genetic connection between the two. It is possible to put into words
the proposition that all the animals and plants of each geological
epoch were annihilated, and that a new set of very similar forms was
created for the next epoch; but it may be doubted if any one who ever
tried to form a distinct mental image of this process of spontaneous
generation on the grandest scale, ever really succeeded in realising it.

Within the last twenty years, the attention of the best palæontologists
has been withdrawn from the hodman’s work of making “new species”
of fossils, to the scientific task of completing our knowledge of
individual species, and tracing out the succession of the forms
presented by any given type in time.

Those who desire to inform themselves of the nature and extent of
the evidence bearing on these questions may consult the works of
Rütimeyer, Gaudry, Kowalewsky, Marsh, and the writer of the present
article. It must suffice, in this place, to say that the successive
forms of the Equine type have been fully worked out; while those of
nearly all the other existing types of Ungulate mammals and of the
_Carnivora_ have been almost as closely followed through the Tertiary
deposits; the gradations between birds and reptiles have been traced;
and the modifications undergone by the _Crocodilia_, from the Triassic
epoch to the present day, have been demonstrated. On the evidence of
palæontology, the evolution of many existing forms of animal life
from their predecessors is no longer an hypothesis, but an historical
fact; it is only the nature of the physiological factors to which that
evolution is due which is still open to discussion.




XII.

THE COMING OF AGE OF “THE ORIGIN OF SPECIES.”


Many of you will be familiar with the aspect of this small
green-covered book. It is a copy of the first edition of the “Origin of
Species,” and bears the date of its production—the 1st of October 1859.
Only a few months, therefore, are needed to complete the full tale of
twenty-one years since its birthday.

Those whose memories carry them back to this time will remember that
the infant was remarkably lively, and that a great number of excellent
persons mistook its manifestations of a vigorous individuality for
mere naughtiness; in fact there was a very pretty turmoil about its
cradle. My recollections of the period are particularly vivid; for,
having conceived a tender affection for a child of what appeared to me
to be such remarkable promise, I acted for some time in the capacity
of a sort of under-nurse, and thus came in for my share of the storms
which threatened the very life of the young creature. For some years it
was undoubtedly warm work; but considering how exceedingly unpleasant
the apparition of the new-comer must have been to those who did not
fall in love with him at first sight, I think it is to the credit of
our age that the war was not fiercer, and that the more bitter and
unscrupulous forms of opposition died away as soon as they did.

I speak of this period as of something past and gone, possessing
merely an historical, I had almost said an antiquarian interest. For,
during the second decade of the existence of the “Origin of Species,”
opposition, though by no means dead, assumed a different aspect. On the
part of all those who had any reason to respect themselves, it assumed
a thoroughly respectful character. By this time, the dullest began to
perceive that the child was not likely to perish of any congenital
weakness or infantile disorder, but was growing into a stalwart
personage, upon whom mere goody scoldings and threatenings with the
birch-rod were quite thrown away.

In fact, those who have watched the progress of science within the last
ten years will bear me out to the full, when I assert that there is no
field of biological inquiry in which the influence of the “Origin of
Species” is not traceable; the foremost men of science in every country
are either avowed champions of its leading doctrines, or at any rate
abstain from opposing them; a host of young and ardent investigators
seek for and find inspiration and guidance in Mr. Darwin’s great work;
and the general doctrine of evolution, to one side of which it gives
expression, obtains, in the phenomena of biology, a firm base of
operations whence it may conduct its conquest of the whole realm of
nature.

History warns us, however, that it is the customary fate of new truths
to begin as heresies and to end as superstitions; and, as matters now
stand, it is hardly rash to anticipate that, in another twenty years,
the new generation, educated under the influences of the present day,
will be in danger of accepting the main doctrines of the “Origin of
Species,” with as little reflection, and it may be with as little
justification, as so many of our contemporaries, twenty years ago,
rejected them.

Against any such a consummation let us all devoutly pray; for the
scientific spirit is of more value than its products, and irrationally
held truths may be more harmful than reasoned errors. Now the essence
of the scientific spirit is criticism. It tells us that whenever a
doctrine claims our assent we should reply, Take it if you can compel
it. The struggle for existence holds as much in the intellectual as in
the physical world. A theory is a species of thinking, and its right
to exist is coextensive with its power of resisting extinction by its
rivals.

From this point of view, it appears to me that it would be but a poor
way of celebrating the Coming of Age of the “Origin of Species,” were I
merely to dwell upon the facts, undoubted and remarkable as they are,
of its far-reaching influence and of the great following of ardent
disciples who are occupied in spreading and developing its doctrines.
Mere insanities and inanities have before now swollen to portentous
size in the course of twenty years. Let us rather ask this prodigious
change in opinion to justify itself; let us inquire whether anything
has happened since 1859, which will explain, on rational grounds, why
so many are worshipping that which they burned, and burning that which
they worshipped. It is only in this way that we shall acquire the means
of judging whether the movement we have witnessed is a mere eddy of
fashion, or truly one with the irreversible current of intellectual
progress, and, like it, safe from retrogressive reaction.

Every belief is the product of two factors: the first is the state of
the mind to which the evidence in favour of that belief is presented;
and the second is the logical cogency of the evidence itself. In both
these respects, the history of biological science during the last
twenty years appears to me to afford an ample explanation of the change
which has taken place; and a brief consideration of the salient events
of that history will enable us to understand why, if the “Origin of
Species” appeared now, it would meet with a very different reception
from that which greeted it in 1859.

One-and-twenty years ago, in spite of the work commenced by Hutton and
continued with rare skill and patience by Lyell, the dominant view
of the past history of the earth was catastrophic. Great and sudden
physical revolutions, wholesale creations and extinctions of living
beings, were the ordinary machinery of the geological epic brought into
fashion by the misapplied genius of Cuvier. It was gravely maintained
and taught that the end of every geological epoch was signalised by a
cataclysm, by which every living being on the globe was swept away,
to be replaced by a brand-new creation when the world returned to
quiescence. A scheme of nature which appeared to be modelled on the
likeness of a succession of rubbers of whist, at the end of each of
which the players upset the table and called for a new pack, did not
seem to shock anybody.

I may be wrong, but I doubt if, at the present time, there is a single
responsible representative of these opinions left. The progress
of scientific geology has elevated the fundamental principle of
uniformitarianism, that the explanation of the past is to be sought
in the study of the present, into the position of an axiom; and the
wild speculations of the catastrophists, to which we all listened with
respect a quarter of a century ago, would hardly find a single patient
hearer at the present day. No physical geologist now dreams of seeking,
outside the range of known natural causes, for the explanation of
anything that happened millions of years ago, any more than he would be
guilty of the like absurdity in regard to current events.

The effect of this change of opinion upon biological speculation
is obvious. For, if there have been no periodical general physical
catastrophes, what brought about the assumed general extinctions
and re-creations of life which are the corresponding biological
catastrophes? And, if no such interruptions of the ordinary course of
nature have taken place in the organic, any more than in the inorganic,
world, what alternative is there to the admission of evolution?

The doctrine of evolution in biology is the necessary result of the
logical application of the principles of uniformitarianism to the
phenomena of life. Darwin is the natural successor of Hutton and Lyell,
and the “Origin of Species” the logical sequence of the “Principles of
Geology.”

The fundamental doctrine of the “Origin of Species,” as of all forms of
the theory of evolution applied to biology, is “that the innumerable
species, genera, and families of organic beings with which the world
is peopled have all descended, each within its own class or group,
from common parents, and have all been modified in the course of
descent.”[92]

And, in view of the facts of geology, it follows that all living
animals and plants “are the lineal descendants of those which lived
long before the Silurian epoch.”[93]

It is an obvious consequence of this theory of descent with
modification, as it is sometimes called, that all plants and animals,
however different they may now be, must, at one time or other, have
been connected by direct or indirect intermediate gradations, and that
the appearance of isolation presented by various groups of organic
beings must be unreal.

No part of Mr. Darwin’s work ran more directly counter to the
prepossessions of naturalists twenty years ago than this. And such
prepossessions were very excusable, for there was undoubtedly a great
deal to be said, at that time, in favour of the fixity of species
and of the existence of great breaks, which there was no obvious or
probable means of filling up, between various groups of organic beings.

For various reasons, scientific and unscientific, much had been made of
the hiatus between man and the rest of the higher mammalia, and it is
no wonder that issue was first joined on this part of the controversy.
I have no wish to revive past and happily forgotten controversies; but
I must state the simple fact that the distinctions in the cerebral and
other characters, which were so hotly affirmed to separate man from all
other animals in 1860, have all been demonstrated to be non-existent,
and that the contrary doctrine is now universally accepted and taught.

But there were other cases in which the wide structural gaps asserted
to exist between one group of animals and another, were by no means
fictitious; and, when such structural breaks were real, Mr. Darwin
could account for them only by supposing that the intermediate forms
which once existed had become extinct. In a remarkable passage he says—

“We may thus account even for the distinctness of whole classes from
each other—for instance, of birds from all other vertebrate animals—by
the belief that many animal forms of life have been utterly lost,
through which the early progenitors of birds were formerly connected
with the early progenitors of the other vertebrate classes.”[94]

Adverse criticism made merry over such suggestions as these. Of course
it was easy to get out of the difficulty by supposing extinction; but
where was the slightest evidence that such intermediate forms between
birds and reptiles as the hypothesis required ever existed? And then
probably followed a tirade upon this terrible forsaking of the paths of
“Baconian induction.”

But the progress of knowledge has justified Mr. Darwin to an extent
which could hardly have been anticipated. In 1862, the specimen of
_Archæopteryx_, which, until the last two or three years, has remained
unique, was discovered; and it is an animal which, in its feathers and
the greater part of its organisation, is a veritable bird, while, in
other parts, it is as distinctly reptilian.

In 1868, I had the honour of bringing under your notice, in this
theatre, the results of investigations made, up to that time, into
the anatomical characters of certain ancient reptiles, which showed
the nature of the modifications in virtue of which the type of the
quadrupedal reptile passed into that of a bipedal bird; and abundant
confirmatory evidence of the justice of the conclusions which I then
laid before you has since come to light.

In 1875, the discovery of the toothed birds of the cretaceous
formation in North America by Professor Marsh completed the series of
transitional forms between birds and reptiles, and removed Mr. Darwin’s
proposition that “many animal forms of life have been utterly lost,
through which the early progenitors of birds were formerly connected
with the early progenitors of the other vertebrate classes,” from the
region of hypothesis to that of demonstrable fact.

In 1859, there appeared to be a very sharp and clear hiatus between
vertebrated and invertebrated animals, not only in their structure,
but, what was more important, in their development. I do not think
that we even yet know the precise links of connection between the two;
but the investigations of Kowalewsky and others upon the development
of _Amphioxus_ and of the _Tunicata_ prove, beyond a doubt, that the
differences which were supposed to constitute a barrier between the two
are non-existent. There is no longer any difficulty in understanding
how the vertebrate type may have arisen from the invertebrate, though
the full proof of the manner in which the transition was actually
effected may still be lacking.

Again, in 1859, there appeared to be a no less sharp separation
between the two great groups of flowering and flowerless plants. It
is only subsequently that the series of remarkable investigations
inaugurated by Hofmeister has brought to light the extraordinary and
altogether unexpected modifications of the reproductive apparatus in
the _Lycopodiaceæ_, the _Rhizocarpeæ_, and the _Gymnospermeæ_, by which
the ferns and the mosses are gradually connected with the Phanerogamic
division of the vegetable world.

So, again, it is only since 1859 that we have acquired that wealth of
knowledge of the lowest forms of life which demonstrates the futility
of any attempt to separate the lowest plants from the lowest animals,
and shows that the two kingdoms of living nature have a common
borderland which belongs to both or to neither.

Thus it will be observed that the whole tendency of biological
investigation, since 1859, has been in the direction of removing the
difficulties which the apparent breaks in the series created at that
time; and the recognition of gradation is the first step towards the
acceptance of evolution.

As another great factor in bringing about the change of opinion which
has taken place among naturalists, I count the astonishing progress
which has been made in the study of embryology. Twenty years ago,
not only were we devoid of any accurate knowledge of the mode of
development of many groups of animals and plants, but the methods of
investigation were rude and imperfect. At the present time, there is
no important group of organic beings the development of which has
not been carefully studied; and the modern methods of hardening and
section-making enable the embryologist to determine the nature of the
process, in each case, with a degree of minuteness and accuracy which
is truly astonishing to those whose memories carry them back to the
beginnings of modern histology. And the results of these embryological
investigations are in complete harmony with the requirements of the
doctrine of evolution. The first beginnings of all the higher forms of
animal life are similar, and however diverse their adult conditions,
they start from a common foundation. Moreover, the process of
development of the animal or the plant from its primary egg or germ is
a true process of evolution—a progress from almost formless to more or
less highly organised matter, in virtue of the properties inherent in
that matter.

To those who are familiar with the process of development, all _à
priori_ objections to the doctrine of biological evolution appear
childish. Any one who has watched the gradual formation of a
complicated animal from the protoplasmic mass, which constitutes the
essential element of a frog’s or a hen’s egg, has had under his eyes
sufficient evidence that a similar evolution of the whole animal world
from the like foundation is, at any rate, possible.

Yet another product of investigation has largely contributed to the
removal of the objections to the doctrine of evolution current in 1859.
It is the proof afforded by successive discoveries that Mr. Darwin
did not over-estimate the imperfection of the geological record. No
more striking illustration of this is needed than a comparison of our
knowledge of the mammalian fauna of the Tertiary epoch in 1859 with its
present condition. M. Gaudry’s researches on the fossils of Pikermi
were published in 1868, those of Messrs. Leidy, Marsh, and Cope, on
the fossils of the Western Territories of America, have appeared
almost wholly since 1870, those of M. Filhol on the phosphorites of
Quercy in 1878. The general effect of these investigations has been
to introduce to us a multitude of extinct animals, the existence of
which was previously hardly suspected; just as if zoologists were to
become acquainted with a country, hitherto unknown, as rich in novel
forms of life as Brazil or South Africa once were to Europeans. Indeed,
the fossil fauna of the Western Territories of America bids fair to
exceed in interest and importance all other known Tertiary deposits
put together; and yet, with the exception of the case of the American
tertiaries, these investigations have extended over very limited areas;
and, at Pikermi, were confined to an extremely small space.


Such appear to me to be the chief events in the history of the progress
of knowledge during the last twenty years, which account for the
changed feeling with which the doctrine of evolution is at present
regarded by those who have followed the advance of biological science,
in respect of those problems which bear indirectly upon that doctrine.

But all this remains mere secondary evidence. It may remove dissent,
but it does not compel assent. Primary and direct evidence in favour of
evolution can be furnished only by palæontology. The geological record,
so soon as it approaches completeness, must, when properly questioned,
yield either an affirmative or a negative answer: if evolution has
taken place, there will its mark be left; if it has not taken place,
there will lie its refutation.

What was the state of matters in 1859? Let us hear Mr. Darwin, who may
be trusted always to state the case against himself as strongly as
possible.

“On this doctrine of the extermination of an infinitude of connecting
links between the living and extinct inhabitants of the world, and at
each successive period between the extinct and still older species,
why is not every geological formation charged with such links? Why
does not every collection of fossil remains afford plain evidence
of the gradation and mutation of the forms of life? We meet with no
such evidence, and this is the most obvious and plausible of the many
objections which may be urged against my theory.”[95]

Nothing could have been more useful to the opposition than this
characteristically candid avowal, twisted as it immediately was into
an admission that the writer’s views were contradicted by the facts of
palæontology. But, in fact, Mr. Darwin made no such admission. What he
says in effect is, not that palæontological evidence is against him,
but that it is not distinctly in his favour; and, without attempting
to attenuate the fact, he accounts for it by the scantiness and the
imperfection of that evidence.

What is the state of the case now, when, as we have seen, the amount
of our knowledge respecting the mammalia of the Tertiary epoch
is increased fifty-fold, and in some directions even approaches
completeness?

Simply this, that, if the doctrine of evolution had not existed,
palæontologists must have invented it, so irresistibly is it forced
upon the mind by the study of the remains of the Tertiary mammalia
which have been brought to light since 1859.

Among the fossils of Pikermi, Gaudry found the successive stages
by which the ancient civets passed into the more modern hyænas;
through the Tertiary deposits of Western America, Marsh tracked the
successive forms by which the ancient stock of the horse has passed
into its present form; and innumerable less complete indications of
the mode of evolution of other groups of the higher mammalia have been
obtained. In the remarkable memoir on the phosphorites of Quercy, to
which I have referred, M. Filhol describes no fewer than seventeen
varieties of the genus _Cynodictis_, which fill up all the interval
between the viverine animals and the bear-like dog _Amphicyon_; nor
do I know any solid ground of objection to the supposition that, in
this _Cynodictis-Amphicyon_ group, we have the stock whence all the
Viveridæ, Felidæ, Hyænidæ, Canidæ, and perhaps the Procyonidæ and
Ursidæ, of the present fauna have been evolved. On the contrary, there
is a great deal to be said in favour.

In the course of summing up his results, M. Filhol observes:—

  “During the epoch of the phosphorites, great changes took
  place in animal forms, and almost the same types as those
  which now exist became defined from one another.

  “Under the influence of natural conditions of which
  we have no exact knowledge, though traces of them are
  discoverable, species have been modified in a thousand
  ways: races have arisen which, becoming fixed, have thus
  produced a corresponding number of secondary species.”

In 1859, language of which this is an unintentional paraphrase,
occurring in the “Origin of Species,” was scouted as wild speculation;
at present, it is a sober statement of the conclusions to which an
acute and critically-minded investigator is led by large and patient
study of the facts of palæontology. I venture to repeat what I have
said before, that, so far as the animal world is concerned, evolution
is no longer a speculation, but a statement of historical fact. It
takes its place alongside of those accepted truths which must be
reckoned with by philosophers of all schools.

Thus when, on the first day of October next, the “Origin of Species”
comes of age, the promise of its youth will be amply fulfilled; and we
shall be prepared to congratulate the venerated author of the book, not
only that the greatness of his achievement and its enduring influence
upon the progress of knowledge have won him a place beside our Harvey;
but, still more, that, like Harvey, he has lived long enough to outlast
detraction and opposition, and to see the stone that the builders
rejected become the head-stone of the corner.




XIII.

THE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE.


The great body of theoretical and practical knowledge which has been
accumulated by the labours of some eighty generations, since the dawn
of scientific thought in Europe, has no collective English name to
which an objection may not be raised; and I use the term “medicine” as
that which is least likely to be misunderstood; though, as every one
knows, the name is commonly applied, in a narrower sense, to one of the
chief divisions of the totality of medical science.

Taken in this broad sense, “medicine” not merely denotes a kind
of knowledge, but it comprehends the various applications of that
knowledge to the alleviation of the sufferings, the repair of the
injuries, and the conservation of the health, of living beings. In
fact, the practical aspect of medicine so far dominates over every
other, that the “Healing Art” is one of its most widely-received
synonyms. It is so difficult to think of medicine otherwise than as
something which is necessarily connected with curative treatment, that
we are apt to forget that there must be, and is, such a thing as a
pure science of medicine—a “pathology” which has no more necessary
subservience to practical ends than has zoology or botany.

The logical connection between this purely scientific doctrine of
disease, or pathology, and ordinary biology, is easily traced.
Living matter is characterised by its innate tendency to exhibit a
definite series of the morphological and physiological phenomena which
constitute organisation and life. Given a certain range of conditions,
and these phenomena remain the same, within narrow limits, for each
kind of living thing. They furnish the normal and typical character
of the species, and, as such, they are the subject-matter of ordinary
biology.

Outside the range of these conditions, the normal course of the
cycle of vital phenomena is disturbed; abnormal structure makes its
appearance, or the proper character and mutual adjustment of the
functions cease to be preserved. The extent and the importance of these
deviations from the typical life may vary indefinitely. They may have
no noticeable influence on the general well-being of the economy, or
they may favour it. On the other hand, they may be of such a nature
as to impede the activities of the organism, or even to involve its
destruction.

In the first case, these perturbations are ranged under the wide and
somewhat vague category of “variations;” in the second, they are called
lesions, states of poisoning, or diseases; and, as morbid states, they
lie within the province of pathology. No sharp line of demarcation can
be drawn between the two classes of phenomena. No one can say where
anatomical variations end and tumours begin, nor where modification
of function, which may at first promote health, passes into disease.
All that can be said is, that whatever change of structure or function
is hurtful belongs to pathology. Hence it is obvious that pathology
is a branch of biology; it is the morphology, the physiology, the
distribution, the ætiology of abnormal life.

However obvious this conclusion may be now, it was nowise apparent
in the infancy of medicine. For it is a peculiarity of the physical
sciences, that they are independent in proportion as they are
imperfect; and it is only as they advance that the bonds which really
unite them all become apparent. Astronomy had no manifest connection
with terrestrial physics before the publication of the “Principia;”
that of chemistry with physics is of still more modern revelation;
that of physics and chemistry with physiology, has been stoutly denied
within the recollection of most of us, and perhaps still may be.

Or, to take a case which affords a closer parallel with that of
medicine. Agriculture has been cultivated from the earliest times,
and, from a remote antiquity, men have attained considerable practical
skill in the cultivation of the useful plants, and have empirically
established many scientific truths concerning the conditions under
which they flourish. But, it is within the memory of many of us, that
chemistry on the one hand, and vegetable physiology on the other,
attained a stage of development such that they were able to furnish
a sound basis for scientific agriculture. Similarly, medicine took
its rise in the practical needs of mankind. At first, studied without
reference to any other branch of knowledge, it long maintained, indeed
still to some extent maintains, that independence. Historically, its
connection with the biological sciences has been slowly established,
and the full extent and intimacy of that connection are only now
beginning to be apparent. I trust I have not been mistaken in supposing
that an attempt to give a brief sketch of the steps by which a
philosophical necessity has become an historical reality, may not be
devoid of interest, possibly of instruction, to the members of this
great Congress, profoundly interested as all are in the scientific
development of medicine.

The history of medicine is more complete and fuller than that of any
other science, except, perhaps, astronomy; and, if we follow back the
long record as far as clear evidence lights us, we find ourselves taken
to the early stages of the civilisation of Greece. The oldest hospitals
were the temples of Æsculapius; to these Asclepeia, always erected on
healthy sites, hard by fresh springs and surrounded by shady groves,
the sick and the maimed resorted to seek the aid of the god of health.
Votive tablets or inscriptions recorded the symptoms, no less than the
gratitude, of those who were healed; and, from these primitive clinical
records, the half-priestly, half-philosophic caste of the Asclepiads
compiled the data upon which the earliest generalisations of medicine,
as an inductive science, were based.

In this state, pathology, like all the inductive sciences at their
origin, was merely natural history; it registered the phenomena of
disease, classified them, and ventured upon a prognosis, wherever
the observation of constant co-existences and sequences suggested a
rational expectation of the like recurrence under similar circumstances.

Further than this it hardly went. In fact, in the then state of
knowledge, and in the condition of philosophical speculation at that
time, neither the causes of the morbid state, nor the _rationale_ of
treatment, were likely to be sought for as we seek for them now. The
anger of a god was a sufficient reason for the existence of a malady,
and a dream ample warranty for therapeutic measures; that a physical
phenomenon must needs have a physical cause was not the implied or
expressed axiom that it is to us moderns.

The great man whose name is inseparately connected with the foundation
of medicine, Hippocrates, certainly knew very little, indeed
practically nothing, of anatomy or physiology; and he would, probably,
have been perplexed, even to imagine the possibility of a connection
between the zoological studies of his contemporary Democritus and
medicine. Nevertheless, in so far as he, and those who worked before
and after him, in the same spirit, ascertained, as matters of
experience, that a wound, or a luxation, or a fever, presented such
and such symptoms, and that the return of the patient to health was
facilitated by such and such measures, they established laws of
nature, and began the construction of the science of pathology. All
true science begins with empiricism—though all true science is such
exactly, in so far as it strives to pass out of the empirical stage
into that of the deduction of empirical from more general truths.
Thus, it is not wonderful, that the early physicians had little or
nothing to do with the development of biological science; and, on the
other hand, that the early biologists did not much concern themselves
with medicine. There is nothing to show that the Asclepiads took any
prominent share in the work of founding anatomy, physiology, zoology,
and botany. Rather do these seem to have sprung from the early
philosophers, who were essentially natural philosophers, animated by
the characteristically Greek thirst for knowledge as such. Pythagoras,
Alcmeon, Democritus, Diogenes of Apollonia, are all credited with
anatomical and physiological investigations; and, though Aristotle is
said to have belonged to an Asclepiad family, and not improbably owed
his taste for anatomical and zoological inquiries to the teachings of
his father, the physician Nicomachus, the “Historia Animalium,” and
the treatise “De Partibus Animalium,” are as free from any allusion to
medicine as if they had issued from a modern biological laboratory.

It may be added, that it is not easy to see in what way it could have
benefited a physician of Alexander’s time to know all that Aristotle
knew on these subjects. His human anatomy was too rough to avail
much in diagnosis; his physiology was too erroneous to supply data
for pathological reasoning. But when the Alexandrian school, with
Erasistratus and Herophilus at their head, turned to account the
opportunities of studying human structure, afforded to them by the
Ptolemies, the value of the large amount of accurate knowledge thus
obtained to the surgeon for his operations, and to the physician for
his diagnosis of internal disorders, became obvious, and a connection
was established between anatomy and medicine, which has ever become
closer and closer. Since the revival of learning, surgery, medical
diagnosis, and anatomy have gone hand in hand. Morgagni called his
great work, “De sedibus et causis morborum per anatomen indagatis,” and
not only showed the way to search out the localities and the causes
of disease by anatomy, but himself travelled wonderfully far upon the
road. Bichat, discriminating the grosser constituents of the organs and
parts of the body, one from another, pointed out the direction which
modern research must take; until, at length, histology, a science of
yesterday, as it seems to many of us, has carried the work of Morgagni
as far as the microscope can take us, and has extended the realm of
pathological anatomy to the limits of the invisible world.

Thanks to the intimate alliance of morphology with medicine, the
natural history of disease has, at the present day, attained a
high degree of perfection. Accurate regional anatomy has rendered
practicable the exploration of the most hidden parts of the organism,
and the determination, during life, of morbid changes in them;
anatomical and histological postmortem investigations have supplied
physicians with a clear basis upon which to rest the classification
of diseases, and with unerring tests of the accuracy or inaccuracy of
their diagnoses.

If men could be satisfied with pure knowledge, the extreme precision
with which, in these days, a sufferer may be told what is happening,
and what is likely to happen, even in the most recondite parts of
his bodily frame, should be as satisfactory to the patient as it is
to the scientific pathologist who gives him the information. But I
am afraid it is not; and even the practising physician, while nowise
underestimating the regulative value of accurate diagnosis, must often
lament that so much of his knowledge rather prevents him from doing
wrong than helps him to do right.

A scorner of physic once said that nature and disease may be compared
to two men fighting, the doctor to a blind man with a club, who strikes
into the _melée_, sometimes hitting the disease, and sometimes hitting
nature. The matter is not mended if you suppose the blind man’s hearing
to be so acute that he can register every stage of the struggle, and
pretty clearly predict how it will end. He had better not meddle at
all, until his eyes are opened—until he can see the exact position of
the antagonists, and make sure of the effect of his blows. But that
which it behoves the physician to see, not, indeed, with his bodily
eye, but with clear, intellectual vision, is a process, and the chain
of causation involved in that process. Disease, as we have seen, is
a perturbation of the normal activities of a living body, and it is,
and must remain, unintelligible, so long as we are ignorant of the
nature of these normal activities. In other words, there could be no
real science of pathology until the science of physiology had reached a
degree of perfection unattained, and indeed unattainable, until quite
recent times.

So far as medicine is concerned, I am not sure that physiology, such
as it was down to the time of Harvey, might as well not have existed.
Nay, it is perhaps no exaggeration to say that, within the memory of
living men, justly renowned practitioners of medicine and surgery knew
less physiology than is now to be learned from the most elementary
text-book; and, beyond a few broad facts, regarded what they did know
as of extremely little practical importance. Nor am I disposed to
blame them for this conclusion; physiology must be useless, or worse
than useless, to pathology, so long as its fundamental conceptions are
erroneous.

Harvey is often said to be the founder of modern physiology; and there
can be no question that the elucidations of the function of the heart,
of the nature of the pulse, and of the course of the blood, put forth
in the ever-memorable little essay, “De motu cordis,” directly worked
a revolution in men’s views of the nature and of the concatenation of
some of the most important physiological processes among the higher
animals; while, indirectly, their influence was perhaps even more
remarkable.

But, though Harvey made this signal and perennially important
contribution to the physiology of the moderns, his general conception
of vital processes was essentially identical with that of the ancients;
and, in the “Exercitationes de generatione,” and notably in the
singular chapter “De calido innato,” he shows himself a true son of
Galen and of Aristotle.

For Harvey, the blood possesses powers superior to those of the
elements; it is the seat of a soul which is not only vegetative, but
also sensitive and motor. The blood maintains and fashions all parts of
the body, “idque summâ cum providentiâ et intellectu in finem certum
agens, quasi ratiocinio quodam uteretur.”

Here is the doctrine of the “pneuma,” the product of the philosophical
mould into which the animism of primitive men ran in Greece, in full
force. Nor did its strength abate for long after Harvey’s time. The
same ingrained tendency of the human mind to suppose that a process
is explained when it is ascribed to a power of which nothing is known
except that it is the hypothetical agent of the process, gave rise, in
the next century, to the animism of Stahl; and, later, to the doctrine
of a vital principle, that “asylum ignorantiæ” of physiologists, which
has so easily accounted for everything and explained nothing, down to
our own times.

Now the essence of modern, as contrasted with ancient, physiological
science appears to me to lie in its antagonism to animistic hypotheses
and animistic phraseology. It offers physical explanations of vital
phenomena, or frankly confesses that it has none to offer. And, so far
as I know, the first person who gave expression to this modern view
of physiology, who was bold enough to enunciate the proposition that
vital phenomena, like all the other phenomena of the physical world,
are, in ultimate analysis, resolvable into matter and motion, was René
Descartes.

The fifty-four years of life of this most original and powerful thinker
are widely overlapped, on both sides, by the eighty of Harvey, who
survived his younger contemporary by seven years, and takes pleasure
in acknowledging the French philosopher’s appreciation of his great
discovery.

In fact, Descartes accepted the doctrine of the circulation as
propounded by “Harvæus médecin d’Angleterre,” and gave a full account
of it in his first work, the famous “Discours de la Méthode,” which
was published in 1637, only nine years after the exercitation “De motu
cordis;” and, though differing from Harvey on some important points
(in which it may be noted, in passing, Descartes was wrong and Harvey
right), he always speaks of him with great respect. And so important
does the subject seem to Descartes, that he returns to it in the
“Traité des Passions,” and in the “Traité de l’Homme.”

It is easy to see that Harvey’s work must have had a peculiar
significance for the subtle thinker, to whom we owe both the
spiritualistic and the materialistic philosophies of modern times. It
was in the very year of its publication, 1628, that Descartes withdrew
into that life of solitary investigation and meditation of which his
philosophy was the fruit. And, as the course of his speculations
led him to establish an absolute distinction of nature between the
material and the mental worlds, he was logically compelled to seek
for the explanation of the phenomena of the material world within
itself; and having allotted the realm of thought to the soul, to see
nothing but extension and motion in the rest of nature. Descartes uses
“thought” as the equivalent of our modern term “consciousness.” Thought
is the function of the soul, and its only function. Our natural heat
and all the movements of the body, says he, do not depend on the soul.
Death does not take place from any fault of the soul, but only because
some of the principal parts of the body become corrupted. The body of a
living man differs from that of a dead man in the same way as a watch
or other automaton (that is to say, a machine which moves of itself)
when it is wound up and has, in itself, the physical principle of the
movements which the mechanism is adapted to perform, differs from the
same watch, or other machine, when it is broken, and the physical
principle of its movement no longer exists. All the actions which are
common to us and the lower animals depend only on the conformation of
our organs, and the course which the animal spirits take in the brain,
the nerves, and the muscles; in the same way as the movement of a watch
is produced by nothing but the force of its spring and the figure of
its wheels and other parts.

Descartes’ “Treatise on Man” is a sketch of human physiology, in which
a bold attempt is made to explain all the phenomena of life, except
those of consciousness, by physical reasonings. To a mind turned in
this direction, Harvey’s exposition of the heart and vessels as a
hydraulic mechanism must have been supremely welcome.

Descartes was not a mere philosophical theorist, but a hardworking
dissector and experimenter, and he held the strongest opinion
respecting the practical value of the new conception which he was
introducing. He speaks of the importance of preserving health, and of
the dependence of the mind on the body being so close that, perhaps,
the only way of making men wiser and better than they are, is to be
sought in medical science. “It is true,” says he, “that as medicine
is now practised, it contains little that is very useful; but without
any desire to depreciate, I am sure that there is no one, even among
professional men, who will not declare that all we know is very little
as compared with that which remains to be known; and that we might
escape an infinity of diseases of the mind, no less than of the body,
and even perhaps from the weakness of old age, if we had sufficient
knowledge of their causes, and of all the remedies with which nature
has provided us.”[96] So strongly impressed was Descartes with this,
that he resolved to spend the rest of his life in trying to acquire
such a knowledge of nature as would lead to the construction of a
better medical doctrine.[97] The anti-Cartesians found material for
cheap ridicule in these aspirations of the philosopher; and it is
almost needless to say that, in the thirteen years which elapsed
between the publication of the “Discours” and the death of Descartes,
he did not contribute much to their realisation. But, for the next
century, all progress in physiology took place along the lines which
Descartes laid down.

The greatest physiological and pathological work of the seventeenth
century, Borelli’s treatise “De Motu Animalium,” is, to all intents
and purposes, a development of Descartes’ fundamental conception; and
the same may be said of the physiology and pathology of Boerhaave,
whose authority dominated in the medical world of the first half of the
eighteenth century.

With the origin of modern chemistry, and of electrical science, in the
latter half of the eighteenth century, aids in the analysis of the
phenomena of life, of which Descartes could not have dreamed, were
offered to the physiologist. And the greater part of the gigantic
progress which has been made in the present century is a justification
of the prevision of Descartes. For it consists, essentially, in a more
and more complete resolution of the grosser organs of the living body
into physico-chemical mechanisms.

“I shall try to explain our whole bodily machinery in such a way, that
it will be no more necessary for us to suppose that the soul produces
such movements as are not voluntary, than it is to think that there is
in a clock a soul which causes it to show the hours.”[98] These words
of Descartes might be appropriately taken as a motto by the author of
any modern treatise on physiology.

But though, as I think, there is no doubt that Descartes was the
first to propound the fundamental conception of the living body as
a physical mechanism, which is the distinctive feature of modern,
as contrasted with ancient physiology, he was misled by the natural
temptation to carry out, in all its details, a parallel between the
machines with which he was familiar, such as clocks and pieces of
hydraulic apparatus, and the living machine. In all such machines there
is a central source of power, and the parts of the machine are merely
passive distributors of that power. The Cartesian school conceived
of the living body as a machine of this kind; and herein they might
have learned from Galen, who, whatever ill use he may have made of the
doctrine of “natural faculties,” nevertheless had the great merit of
perceiving that local forces play a great part in physiology.

The same truth was recognised by Glisson, but it was first prominently
brought forward in the Hallerian doctrine of the “vis insita” of
muscles. If muscle can contract without nerve, there is an end of the
Cartesian mechanical explanation of its contraction by the influx of
animal spirits.

The discoveries of Trembley tended in the same direction. In the
freshwater _Hydra_, no trace was to be found of that complicated
machinery upon which the performance of the functions in the higher
animals was supposed to depend. And yet the hydra moved, fed, grew,
multiplied, and its fragments exhibited all the powers of the whole.
And, finally, the work of Caspar F. Wolff,[99] by demonstrating the
fact that the growth and development of both plants and animals take
place antecedently to the existence of their grosser organs, and are,
in fact, the causes and not the consequences of organisation (as then
understood), sapped the foundations of the Cartesian physiology as a
complete expression of vital phenomena.

For Wolff, the physical basis of life is a fluid, possessed of a “vis
essentialis” and a “solidescibilitas,” in virtue of which it gives rise
to organisation; and, as he points out, this conclusion strikes at the
root of the whole iatro-mechanical system.

In this country, the great authority of John Hunter exerted a similar
influence; though it must be admitted that the too sibylline utterances
which are the outcome of Hunter’s struggles to define his conceptions
are often susceptible of more than one interpretation. Nevertheless,
on some points Hunter is clear enough. For example, he is of opinion
that “Spirit is only a property of matter” (“Introduction to Natural
History,” p. 6), he is prepared to renounce animism (_l.c._ p. 8),
and his conception of life is so completely physical that he thinks
of it as something which can exist in a state of combination in the
food. “The aliment we take in has in it, in a fixed state, the real
life; and this does not become active until it has got into the lungs;
for there it is freed from its prison” (“Observations on Physiology,”
p. 113). He also thinks that “It is more in accord with the general
principles of the animal machine to suppose that none of its effects
are produced from any mechanical principle whatever; and that every
effect is produced from an action in the part; which action is produced
by a stimulus upon the part which acts, or upon some other part with
which this part sympathises so as to take up the whole action” (_l.c._
p. 152).

And Hunter is as clear as Wolff, with whose work he was probably
unacquainted, that “whatever life is, it most certainly does not depend
upon structure or organisation” (_l.c._ p. 114).

Of course it is impossible that Hunter could have intended to deny
the existence of purely mechanical operations in the animal body.
But while, with Borelli and Boerhaave, he looked upon absorption,
nutrition, and secretion as operations effected by means of the small
vessels, he differed from the mechanical physiologists, who regarded
these operations as the result of the mechanical properties of the
small vessels, such as the size, form, and disposition of their canals
and apertures. Hunter, on the contrary, considers them to be the effect
of properties of these vessels which are not mechanical but vital. “The
vessels,” says he, “have more of the polypus in them than any other
part of the body,” and he talks of the “living and sensitive principles
of the arteries,” and even of the “dispositions or feelings of the
arteries.” “When the blood is good and genuine the sensations of the
arteries, or the dispositions for sensation, are agreeable.... It is
then they dispose of the blood to the best advantage, increasing the
growth of the whole, supplying any losses, keeping up a due succession,
etc.” (_l.c._ p. 133).

If we follow Hunter’s conceptions to their logical issue, the life of
one of the higher animals is essentially the sum of the lives of all
the vessels, each of which is a sort of physiological unit, answering
to a polype; and, as health is the result of the normal “action of the
vessels,” so is disease an effect of their abnormal action. Hunter thus
stands in thought, as in time, midway between Borelli on the one hand,
and Bichat on the other.

The acute founder of general anatomy, in fact, outdoes Hunter in his
desire to exclude physical reasonings from the realm of life. Except in
the interpretation of the action of the sense organs, he will not allow
physics to have anything to do with physiology.

“To apply the physical sciences to physiology is to explain the
phenomena of living bodies by the laws of inert bodies. Now this
is a false principle, hence all its consequences are marked with
the same stamp. Let us leave to chemistry its affinity; to physics,
its elasticity and its gravity. Let us invoke for physiology only
sensibility and contractility.”[100]

Of all the unfortunate dicta of men of eminent ability this seems
one of the most unhappy, when we think of what the application of
the methods and the data of physics and chemistry has done towards
bringing physiology into its present state. It is not too much to say
that one half of a modern text-book of physiology consists of applied
physics and chemistry; and that it is exactly in the exploration of the
phenomena of sensibility and contractility that physics and chemistry
have exerted the most potent influence.

Nevertheless, Bichat rendered a solid service to physiological progress
by insisting upon the fact that what we call life, in one of the higher
animals, is not an indivisible unitary archæus dominating, from its
central seat, the parts of the organism, but a compound result of the
synthesis of the separate lives of those parts.

“All animals,” says he, “are assemblages of different organs, each of
which performs its function and concurs, after its fashion, in the
preservation of the whole. They are so many special machines in the
general machine which constitutes the individual. But each of these
special machines is itself compounded of many tissues of very different
natures, which in truth constitute the elements of those organs”
(_l.c._ lxxix.) “The conception of a proper vitality is applicable only
to these simple tissues, and not to the organs themselves” (_l.c._
lxxxiv.)

And Bichat proceeds to make the obvious application of this doctrine of
synthetic life, if I may so call it, to pathology. Since diseases are
only alterations of vital properties, and the properties of each tissue
are distinct from those of the rest, it is evident that the diseases of
each tissue must be different from those of the rest. Therefore, in any
organ composed of different tissues, one may be diseased and the other
remain healthy; and this is what happens in most cases (_l.c._ lxxxv.)

In a spirit of true prophecy, Bichat says, “We have arrived at an
epoch, in which pathological anatomy should start afresh.” For, as the
analysis of the organs had led him to the tissues, as the physiological
units of the organism; so, in a succeeding generation, the analysis
of the tissues led to the cell as the physiological element of the
tissues. The contemporaneous study of development brought out the same
result; and the zoologists and botanists, exploring the simplest and
the lowest forms of animated beings, confirmed the great induction of
the cell theory. Thus the apparently opposed views, which have been
battling with one another ever since the middle of the last century,
have proved to be each half the truth.

The proposition of Descartes that the body of a living man is a
machine, the actions of which are explicable by the known laws of
matter and motion, is unquestionably largely true. But it is also
true, that the living body is a synthesis of innumerable physiological
elements, each of which may nearly be described, in Wolff’s words, as a
fluid possessed of a “vis essentialis,” and a “solidescibilitas”; or,
in modern phrase, as protoplasm susceptible of structural metamorphosis
and functional metabolism: and that the only machinery, in the precise
sense in which the Cartesian school understood mechanism, is, that
which co-ordinates and regulates these physiological units into an
organic whole.

In fact, the body is a machine of the nature of an army, not of that
of a watch or of a hydraulic apparatus. Of this army each cell is a
soldier, an organ a brigade, the central nervous system headquarters
and field telegraph, the alimentary and circulatory system the
commissariat. Losses are made good by recruits born in camp, and the
life of the individual is a campaign, conducted successfully for a
number of years, but with certain defeat in the long run.

The efficacy of an army, at any given moment, depends on the health of
the individual soldier, and on the perfection of the machinery by which
he is led and brought into action at the proper time; and, therefore,
if the analogy holds good, there can be only two kinds of diseases, the
one dependent on abnormal states of the physiological units, the other
on perturbations of their co-ordinating and alimentative machinery.

Hence, the establishment of the cell theory, in normal biology, was
swiftly followed by a “cellular pathology,” as its logical counterpart.
I need not remind you how great an instrument of investigation this
doctrine has proved in the hands of the man of genius to whom its
development is due, and who would probably be the last to forget that
abnormal conditions of the co-ordinative and distributive machinery of
the body are no less important factors of disease.

Henceforward, as it appears to me, the connection of medicine with the
biological sciences is clearly defined. Pure pathology is that branch
of biology which defines the particular perturbation of cell-life, or
of the co-ordinating machinery, or of both, on which the phenomena of
disease depend.

Those who are conversant with the present state of biology will hardly
hesitate to admit that the conception of the life of one of the higher
animals as the summation of the lives of a cell aggregate, brought into
harmonious action by a co-ordinative machinery formed by some of these
cells, constitutes a permanent acquisition of physiological science.
But the last form of the battle between the animistic and the physical
views of life is seen in the contention whether the physical analysis
of vital phenomena can be carried beyond this point or not.

There are some to whom living protoplasm is a substance, even such as
Harvey conceived the blood to be, “summâ cum providentiâ et intellectu
in finem certum agens, quasi ratiocinio quodam;” and who look with as
little favour as Bichat did, upon any attempt to apply the principles
and the methods of physics and chemistry to the investigation of the
vital processes of growth, metabolism, and contractility. They stand
upon the ancient ways; only, in accordance with that progress towards
democracy, which a great political writer has declared to be the fatal
characteristic of modern times, they substitute a republic formed by a
few billion of “animulæ” for the monarchy of the all-pervading “anima.”

Others, on the contrary, supported by a robust faith in the universal
applicability of the principles laid down by Descartes, and seeing
that the actions called “vital” are, so far as we have any means of
knowing, nothing but changes of place of particles of matter, look to
molecular physics to achieve the analysis of the living protoplasm
itself into a molecular mechanism. If there is any truth in the
received doctrines of physics, that contrast between living and inert
matter, on which Bichat lays so much stress, does not exist. In nature,
nothing is at rest, nothing is amorphous; the simplest particle of
that which men in their blindness are pleased to call “brute matter”
is a vast aggregate of molecular mechanisms performing complicated
movements of immense rapidity, and sensitively adjusting themselves
to every change in the surrounding world. Living matter differs from
other matter in degree and not in kind; the microcosm repeats the
macrocosm; and one chain of causation connects the nebulous original of
suns and planetary systems with the protoplasmic foundation of life and
organisation.

From this point of view, pathology is the analogue of the theory of
perturbations in astronomy; and therapeutics resolves itself into
the discovery of the means by which a system of forces competent to
eliminate any given perturbation may be introduced into the economy.
And, as pathology bases itself upon normal physiology, so therapeutics
rests upon pharmacology; which is, strictly speaking, a part of the
great biological topic of the influence of conditions on the living
organism, and has no scientific foundation apart from physiology.

It appears to me that there is no more hopeful indication of the
progress of medicine towards the ideal of Descartes than is to
be derived from a comparison of the state of pharmacology, at the
present day, with that which existed forty years ago. If we consider
the knowledge positively acquired, in this short time, of the _modus
operandi_ of urari, of atropia, of physostigmin, of veratria, of casca,
of strychnia, of bromide of potassium, of phosphorus, there can surely
be no ground for doubting that, sooner or later, the pharmacologist
will supply the physician with the means of affecting, in any desired
sense, the functions of any physiological element of the body. It will,
in short, become possible to introduce into the economy a molecular
mechanism which, like a very cunningly-contrived torpedo, shall find
its way to some particular group of living elements, and cause an
explosion among them, leaving the rest untouched.

The search for the explanation of diseased states in modified
cell-life; the discovery of the important part played by parasitic
organisms in the ætiology of disease; the elucidation of the action of
medicaments by the methods and the data of experimental physiology;
appear to me to be the greatest steps which have ever been made towards
the establishment of medicine on a scientific basis. I need hardly say
they could not have been made except for the advance of normal biology.

There can be no question, then, as to the nature or the value of the
connection between medicine and the biological sciences. There can
be no doubt that the future of pathology and of therapeutics, and,
therefore, that of practical medicine, depends upon the extent to
which those who occupy themselves with these subjects are trained in
the methods and impregnated with the fundamental truths of biology.

And, in conclusion, I venture to suggest that the collective sagacity
of this Congress could occupy itself with no more important question
than with this: How is medical education to be arranged, so that,
without entangling the student in those details of the systematist
which are valueless to him, he may be enabled to obtain a firm grasp of
the great truths respecting animal and vegetable life, without which,
notwithstanding all the progress of scientific medicine, he will still
find himself an empiric?




FOOTNOTES:

[1] See _Joseph Priestley_, p. 94, _infra_.

[2] The advocacy of the introduction of physical science into general
education by George Combe and others commenced a good deal earlier; but
the movement had acquired hardly any practical force before the time to
which I refer.

[3] _Essays in Criticism_, p. 37.

[4] “Quamvis enim melius sit bene facere quam nosse, prius tamen est
nosse quam facere.”—“Karoli Magni Regis Constitutio de Scholis per
singula Episcopia et Monasteria instituendis,” addressed to the Abbot
of Fulda. Baluzius, “Capitularia Regum Francorum,” T. i., p. 202.

[5] Inaugural Address delivered to the University of St. Andrew
February 1, 1867, by J. S. Mill, Rector of the University (pp. 32, 33).

[6] “Suggestions for Academical Organisation, with Especial Reference
to Oxford.” By the Rector of Lincoln.

[7] Goethe, _Zahme Xenien, Vierte Abtheilung_. I should be glad to take
credit for the close and vigorous English version; but it is my wife’s,
and not mine.

[8] See the “Programme” for 1878, issued by the Society of Arts, p. 14.

[9] It is perhaps advisable to remark that the important question of
the professional education of managers of industrial works is not
touched in the foregoing remarks.

[10] “Quasi cursores, vitaï lampada tradunt.”—LUCR. _De Rerum Nat._ ii.
78.

[11] “Life and Correspondence of Dr. Priestley,” by J. T. Rutt. Vol. i.
p. 50.

[12] “Autobiography,” §§ 100, 101.

[13] See “The Life of Mary Anne Schimmelpenninck.” Mrs.
Schimmelpenninck (_née_ Galton) remembered Priestley very well, and her
description of him is worth quotation:—“A man of admirable simplicity,
gentleness and kindness of heart, united with great acuteness of
intellect. I can never forget the impression produced on me by the
serene expression of his countenance. He, indeed, seemed present with
God by recollection, and with man by cheerfulness. I remember that,
in the assembly of these distinguished men, amongst whom Mr. Boulton,
by his noble manner, his fine countenance (which much resembled that
of Louis XIV.), and princely munificence, stood pre-eminently as the
great Mecænas; even as a child, I used to feel, when Dr. Priestley
entered after him, that the glory of the one was terrestrial, that of
the other celestial; and utterly far as I am removed from a belief in
the sufficiency of Dr. Priestley’s theological creed, I cannot but here
record this evidence of the eternal power of any portion of the truth
held in its vitality.”

[14] Even Mrs. Priestley, who might be forgiven for regarding the
destroyers of her household gods with some asperity, contents herself,
in writing to Mrs. Barbauld, with the sarcasm that the Birmingham
people “will scarcely find so many respectable characters, a second
time, to make a bonfire of.”

[15] “Experiments and Observations on Different Kinds of Air,” vol. ii.
p. 31.

[16] _Ibid._ pp. 34, 35.

[17] “Experiments and Observations on Different Kinds of Air,” vol. ii.
p. 40.

[18] _Ibid._ p. 48.

[19] _Ibid._ p. 55.

[20] “Experiments and Observations on Different Kinds of Air,” vol. ii.
p. 60. The italics are Priestley’s own.

[21] “In all the newspapers and most of the periodical publications
I was represented as an unbeliever in Revelation, and no better than
an atheist.”—“Autobiography,” Rutt. vol. i. p. 124. “On the walls of
houses, etc., and especially where I usually went, were to be seen, in
large characters, ‘MADAN FOR EVER; DAMN PRIESTLEY; NO PRESBYTERIANISM;
DAMN THE PRESBYTERIANS,’ etc. etc.; and, at one time, I was followed by
a number of boys, who left their play, repeating what they had seen on
the walls, and shouting out, ‘_Damn Priestley; damn him, damn him, for
ever, for ever_,’ etc. etc. This was no doubt a lesson which they had
been taught by their parents, and what they, I fear, had learned from
their superiors.”—“Appeal to the Public on the Subject of the Riots at
Birmingham.”

[22] First Series. “On Some of the Peculiarities of the Christian
Religion.” Essay I. Revelation of a Future State.

[23] Not only is Priestley at one with Bishop Courtenay in this
matter, but with Hartley and Bonnet, both of them stout champions of
Christianity. Moreover, Archbishop Whately’s essay is little better
than an expansion of the first paragraph of Hume’s famous essay on
the Immortality of the Soul:—“By the mere light of reason it seems
difficult to prove the immortality of the soul; the arguments for it
are commonly derived either from metaphysical topics, or moral, or
physical. But it is in reality the Gospel, and the Gospel alone, that
has brought _life and immortality to light_.” It is impossible to
imagine that a man of Whately’s tastes and acquirements had not read
Hume or Hartley, though he refers to neither.

[24] “Essay on the First Principles of Government.” Second edition,
1771, p. 13.

[25] “Utility of Establishments,” in “Essay on First Principles of
Government,” p. 198, 1771.

[26] In 1732 Doddridge was cited for teaching without the Bishop’s
leave, at Northampton.

[27] The recent proceedings of the House of Commons throw a doubt,
which it is to be hoped may speedily be removed, on the accuracy of
this statement. (September 1881.)

[28] “Discours sur les révolutions de la surface du globe,” _Recherches
sur les ossemens fossiles_, Ed. iv. t. i. p. 185.

[29] “On the Eclipses of Agathocles, Thales, and Xerxes,”
_Philosophical Transactions_, vol. cxliii.

[30] There is every reason to believe that living plants, like living
animals, always respire, and, in respiring, absorb oxygen and give off
carbonic acid; but, that in green plants exposed to daylight or to
the electric light, the quantity of oxygen evolved in consequence of
the decomposition of carbonic acid by a special apparatus which green
plants possess exceeds that absorbed in the concurrent respiratory
process.

[31] Darwin, “Insectivorous Plants,” p. 289.

[32] I purposely assume that the air with which the bean is supplied in
the case stated contains no ammoniacal salts.

[33] The recent researches of Pringsheim have raised a host of
questions as to the exact share taken by chlorophyll in the chemical
operations which are effected by the green parts of plants. It may
be that the chlorophyll is only a constant concomitant of the actual
deoxidising apparatus.

[34] “Researches in the Life-history of a Cercomonad: a Lesson in
Biogenesis;” and “Further Researches in the Life-history of the
Monads.”—“Monthly Microscopical Journal,” 1873.

[35] Excellently described by Stein, almost all of whose statements I
have verified.

[36] “Histoire des Sciences Naturelles,” i. p. 152.

[37] The text I have followed is that given by Aubert and Wimmer,
“Aristoteles Thierkunde; kritisch berichtigter Text mit deutschen
Uebersetzung;” but I have tried here and there to bring the English
version rather closer to the original than the German translation,
excellent as it is, seems to me to be.

[38] In modern works on Veterinary Anatomy the lungs are sometimes
described as two lobes of a single organ.

[39] “Histoire des Sciences Naturelles.”—t. i. p. 130.

[40] “Aristotle, a Chapter from the History of Science.”

[41] I quote, here and always, Cousin’s edition of the works of
Descartes, as most convenient for reference. It is entitled “Œuvres
complètes de Descartes,” publiées par Victor Cousin. 1824.

[42] “Les Passions de l’Âme,” Article xxxiii.

[43] “Recherches physiologiques sur la Vie et la Mort.” Par Xav.
Bichat. Art. Sixième.

[44] Locke (_Human Understanding_, Book II., chap. viii. 37) uses
Descartes’ illustration for the same purpose, and warns us that “most
of the ideas of sensation are no more the likeness of something
existing without us than the names that stand for them are the likeness
of our ideas, which yet, upon hearing, they are apt to excite in us,” a
declaration which paved the way for Berkeley.

[45] “Passions de l’Âme,” Art. xxxvi.

[46] “Quamcumque Bruti actionem, velut automati mechanici motum
artificialem, in eo consistere quod se primò sensibile aliquod spiritus
animales afficiens, eosque introrsum convertens, _sensionem_ excitat,
à qua mox iidem spiritus, velut undulatione reflexâ denuo retrorsum
commoti atque pro concinno ipsius fabricæ organorum, et partium ordine,
in certos nervos musculosque determinati, respectivos _membrorum motus_
perficiunt.”—WILLIS: “De Animâ Brutorum,” p. 5, ed. 1763.

[47] “Les Passions de l’Âme,” xlii.

[48] Haller, “Primæ Lineæ,” ed. iii. “Sensus Interni,” dlviii.

[49] “Réponse de M. Descartes à M. Morus.” 1649. “Œuvres,” tome x. p.
204. “Mais le plus grand de tous les préjugés que nous ayons retenus de
notre enfance, est celui de croire que les bêtes pensent,” etc.

[50] Malebranche states the view taken by orthodox Cartesians in
1689 very forcibly: “Ainsi dans les chiens, les chats, et les autres
animaux, il n’y a ny intelligence, ny âme spirituelle comme on l’entend
ordinairement. Ils mangent sans plaisir; ils crient sans douleur; ils
croissent sans le sçavoir; ils ne désirent rien; ils ne connoissent
rien; et s’ils agissent avec adresse et d’une manière qui marque
l’intelligence, c’est que Dieu les faisant pour les conserver, il a
conformé leurs corps de telle manière, qu’ils évitent organiquement,
sans le sçavoir, tout ce qui peut les détruire et qu’ils semblent
craindre.” (“Feuillet de Conches. Méditations Métaphysiques et
Correspondance de N. Malebranche. Neuvième Méditation.” 1841.)

[51] See the remarkable essay of Göltz, “Beiträge zur Lehre von den
Functionen der Nervencentren des Frosches,” published in 1869. I have
repeated Göltz’s experiments, and obtained the same results.

[52] “De l’Automatisme de la Mémoire et du Souvenir, dans le
Somnambulisme pathologique.” Par le Dr. E. Mesnet, Médecin de l’Hôpital
Saint-Antoine. “L’Union Médicale,” Juillet 21 et 23, 1874. My attention
was first called to a summary of this remarkable case, which appeared
in the “Journal des Débats” for the 7th of August 1874, by my friend
General Strachey, F.R.S.

[53] Those who have had occasion to become acquainted with the
phenomena of somnambulism and of mesmerism, will be struck with the
close parallel which they present to the proceedings of F. in his
abnormal state. But the great value of Dr. Mesnet’s observations lies
in the fact that the abnormal condition is traceable to a definite
injury to the brain, and that the circumstances are such as to keep
us clear of the cloud of voluntary and involuntary fictions in which
the truth is too often smothered in such cases. In the unfortunate
subjects of such abnormal conditions of the brain, the disturbance of
the sensory and intellectual faculties is not unfrequently accompanied
by a perturbation of the moral nature, which may manifest itself in a
most astonishing love of lying for its own sake. And, in this respect,
also, F.’s case is singularly instructive, for though, in his normal
state, he is a perfectly honest man, in his abnormal condition he is
an inveterate thief, stealing and hiding away whatever he can lay
hands on, with much dexterity, and with an absurd indifference as to
whether the property is his own or not. Hoffman’s terrible conception
of the “Doppelt-gänger” is realised by men in this state—who live two
lives, in the one of which they may be guilty of the most criminal
acts, while, in the other, they are eminently virtuous and respectable.
Neither life knows anything of the other. Dr. Mesnet states that he
has watched a man in his abnormal state elaborately prepare to hang
himself, and has let him go on until asphyxia set in, when he cut him
down. But on passing into the normal state the would-be suicide was
wholly ignorant of what had happened. The problem of responsibility is
here as complicated as that of the prince-bishop, who swore as a prince
and not as a bishop. “But, highness, if the prince is damned, what will
become of the bishop?” said the peasant.

[54] “Lay Sermons, Essays and Reviews,” p. 355.

[55] “Essai de Psychologie,” chap. xxvii.

[56] In justice to Reid, however, it should be stated that the chapters
on sensation in the “Essays on the Intellectual Powers” (1785) exhibit
a great improvement. He is, in fact, in advance of his commentator, as
the note to Essay II. chap. ii. p. 248 of Hamilton’s edition shows.

[57] Haller, amplifying Descartes, writes in the “Primæ Lineæ,”
CCCLXVI.—“Non est adeo obscurum sensum omnem oriri ab objecti
sensibilis impressione in nervum quemcumque corporis humani, et eamdem
per eum nervum ad cerebrum pervenientem tunc demum representari animæ,
quando cerebrum adtigit. Ut etiam hoc falsum sit animam inproximo per
sensoria nervorumque ramos sentire.”... DLVII.—“Dum ergo sentimus
quinque diversissima entia conjunguntur: corpus quod sentimus:
organi sensorii adfectio ab eo corpore: cerebri adfectio a sensorii
percussione nata: in anima nata mutatio: animæ denique conscientia et
sensationis adperceptio.” Nevertheless, Sir William Hamilton gravely
informs his hearers:—“We have no more right to deny that the mind feels
at the finger points, as consciousness assures us, than to assert
that it thinks exclusively in the brain.”—“Lecture on Metaphysics and
Logic,” ii. p. 128. “We have no reason whatever to doubt the report
of consciousness, that we actually perceive at the external point of
sensation, and that we perceive the material reality.”—_Ibid._ p. 129.

[58] “Observations on Man,” vol. i. p. 11.

[59] _Ibid._ p. 8. The speculations of Bonnet are remarkably similar
to those of Hartley; and they appear to have originated independently,
though the “Essai de Psychologie” (1754) is of five years’ later date
than the “Observations on Man” (1749).

[60] “An Inquiry into the Human Mind on the Principles of Common
Sense,” chap. ii. § 2. Reid affirms that “it is genius, and not the
want of it, that adulterates philosophy, and fills it with error and
false theory;” and no doubt his own lucubrations are free from the
smallest taint of the impurity to which he objects. But, for want of
something more than that sort of “common sense,” which is very common
and a little dull, the contemner of genius did not notice that the
admission here made knocks so big a hole in the bottom of “common sense
philosophy,” that nothing can save it from foundering in the dreaded
abyss of Idealism.

[61] The following diagrammatic scheme may help to elucidate the theory
of sensation:—

                        Mediate Knowledge
  ┌────────────────────────────┴──────────────────────────────┐     Immediate
                               Sensiferous Apparatus                Knowledge
                    ┌─────────────────────┴────────────────────┐ ┌───────┴───────┐
  Objects of sense │ Receptive    Transmissive  Sensificatory   │ Sensations  and
                   │(Sense Organ)   (Nerve)      (Sensorium)    │ other States of
                   │                                            │  Consciousness
                   │                                            │
    Hypothetical   │                                            │   Hypothetical
    Substance of   │                                            │   Substance of
       Matter      │                                            │      Mind

  └──────────────────────────────────┬─────────────────────────┘ └───────┬───────┘
                               Physical World                     Mental World
  └───────┬───────┘└────────────────────────────┬────────────────────────────────┘
       Not Self                                Self
  └───────────────────────────────┬────────────────────────────┘ └───────┬───────┘
                          Non-Ego or Object                      Ego or Subject

Immediate knowledge is confined to states of consciousness, or, in
other words, to the phenomena of mind. Knowledge of the physical
world, or of one’s own body and of objects external to it, is a system
of beliefs or judgments based on the sensations. The term “self” is
applied not only to the series of mental phenomena which constitute the
ego, but to the fragment of the physical world which is their constant
concomitant. The corporeal self, therefore, is part of the non-ego;
and is objective in relation to the ego as subject.

[62] “Chaque fibre est une espèce de touche ou de marteau destiné à
rendre un certain ton.”—Bonnet, “Essai de Psychologie,” chap. iv.

[63] The “Exercitationes de Generatione Animalium,” which Dr. George
Ent extracted from him and published in 1651.

[64] “De Generatione Animalium,” lib ii. cap. x.

[65] “De Generatione,” lib. ii. cap. iv.

[66] “Cependant, pour revenir aux formes ordinaires ou aux âmes
matérielles, cette durée qu’il leur faut attribuer à la place de celle
qu’on avoit attributée aux atomes pourroit faire douter si elles ne
vont pas de corps en corps; ce qui seroit la métempsychose, à peu
près comme quelques philosophes ont cru la transmission du mouvement
et celle des espèces. Mais cette imagination est bien éloignée de la
nature des choses. Il n’y a point de tel passage; et c’est ici où les
transformations de Messieurs Swammerdam, Malpighi, et Leewenhoek, qui
sont des plus excellens observateurs de notre tems, sont venues à mon
secours, et m’ont fait admettre plus aisément, que l’animal, et toute
autre substance organisée ne commence point lorsque nous le croyons, et
que sa generation apparente n’est qu’une développement et une espèce
d’augmentation. Aussi ai je remarqué que l’auteur de la “Recherche de
la Verité,” M. Regis, M. Hartsocker, et d’autres habiles hommes n’ont
pas été fort éloignés de ce sentiment.” Leibnitz, “Système nouveau
de la Nature,” 1695. The doctrine of “Emboîtement” is contained in
the “Considérations sur le principe de vie,” 1705; the preface to the
“Theodicée,” 1710; and the “Principes de la Nature et de la Grace” (§
6), 1718.

[67] “Il est vrai que la pensée la plus raisonnable et la plus conforme
à l’experience sur cette question très difficile de la formation du
fœtus; c’est que les enfans sont déja presque tout formés avant même
l’action par laquelle ils sont conçus; et que leurs mères ne font que
leur donner l’accroissement ordinaire dans le temps de la grossesse.”
“De la Recherche de la Verité,” livre ii. chap. vii. p. 334, 7th ed.,
1721.

[68] The writer is indebted to Dr. Allen Thomson for reference to
the evidence contained in a note to Haller’s edition of Boerhaave’s
“Prælectiones Academicæ,” vol. v. pt ii. p. 497, published in 1744,
that Haller originally advocated epigenesis.

[69] “Considérations sur les Corps organisés,” chap. x.

[70] Bonnet had the courage of his opinions, and in the “Palingénésie
Philosophique,” part vi. chap, iv., he develops a hypothesis which
he terms “évolution naturelle;” and which, making allowance for his
peculiar views of the nature of generation, bears no small resemblance
to what is understood by “evolution” at the present day:—

“Si la volonté divine a créé par un seul Acte l’Universalité des êtres,
d’où venoient ces plantes et ces animaux dont Moyse nous decrit la
Production au troisieme et au cinquieme jour du renouvellement de notre
monde?

“Abuserois-je de la liberté de conjectures si je disois, que les
Plantes et les Animaux qui existent aujourd’hui sont parvenus par une
sorte d’evolution naturelle des Etres organisés qui peuplaient ce
premier Monde, sorti immédiatement des MAINS du CREATEUR?...

“Ne supposons que trois révolutions. La Terre vient de sortir des MAINS
du CREATEUR. Des causes preparées par sa SAGESSE font développer de
toutes parts les Germes. Les Etres organisés commencent à jouir de
l’existence. Ils étoient probablement alors bien différens de ce qu’ils
sont aujourd’hui. Ils l’etoient autant que ce premier Monde différoit
de celui que nous habitons. Nous manquons de moyens pour juger de ces
dissemblances, et peut-être que le plus habile Naturaliste qui auroit
été placé dans ce premier Monde y auroit entièrement méconnu nos
Plantes et nos Animaux.”

[71] “Ce mot (germe) ne désignera pas seulement un corps organisé
_réduit en petit_; il désignera encore toute espèce de _préformation
originelle dont un Tout organique pent résulter comme de son principe
immédiat_.”—“Palingénésie Philosophique,” part x. chap. ii.

[72] “M. Cuvier considérant que tous les êtres organisés sont dérivés
de parens, et ne voyant dans la nature aucune force capable de produire
l’organisation, croyait à la pré-existence des germes; non pas à la
pré-existence d’un être tout formé, puisqu’il est bien évident que
ce n’est que par des développemens successifs que l’être acquiert
sa forme; mais, si l’on peut s’exprimer ainsi, à la pré-existence
du _radical de l’être_, radical qui existe avant que la série des
évolutions ne commence, et qui remonte certainement, suivant la belle
observation de Bonnet, à plusieurs generations.”—Laurillard, “Éloge de
Cuvier,” note 12.

[73] “Histoire Naturelle,” tom. ii. ed. ii. 1750, p. 350.

[74] _Ibid._ p. 351.

[75] See particularly Buffon, _l.c._ p. 41.

[76] “Exercitationes de Generatione.” Ex. 62, “Ovum esse primordium
commune omnibus animalibus.”

[77] In some cases of sexless multiplication the germ is a
cell-aggregate—if we call germ only that which is already detached from
the parent organism.

[78] Harvey, “Exercitationes de Generatione.” Ex. 45, “Quænam sit pulli
materia et quomodo fiat in Ovo.”

[79] Not yet actually demonstrated in the case of phænogamous plants.

[80] As Buffon has well said:—“L’idée de ramener l’explication de tous
les phénomènes à des principes mecaniques est assurement grande et
belle, ce pas est le plus hardi qu’on peut faire en philosophie, et
c’est Descartes qui l’a fait.”—_l.c._ p. 50.

[81] “Principes de la Philosophie,” Troisième partie, § 45.

[82] “Ethices,” Pars tertia, Præfatio.

[83] “Système de la Nature.” “Essai sur la Formation des Corps
Organisés,” 1751, xiv.

[84] “Considérations Philosophiques sur la gradation naturelle des
formes de l’être; ou les essais de la nature qui apprend à faire
l’homme,” 1768.

[85] “Recherches sur les causes des principaux faits physiques,” par
J. B. Lamarck. Paris. Seconde année de la République. In the preface,
Lamarck says that the work was written in 1776, and presented to the
Academy in 1780; but it was not published before 1794, and, at that
time, it presumably expressed Lamarck’s mature views. It would be
interesting to know what brought about the change of opinion manifested
in the “Recherches sur l’organisation des corps vivants,” published
only seven years later.

[86] See the “Historical Sketch” prefixed to the last edition of the
“Origin of Species.”

[87] “First Principles” and “Principles of Biology,” 1860-1864.

[88] “Generelle Morphologie,” 1866.

[89] “Il s’agit donc de prouver que la série qui constitute l’échelle
animale réside essentiellement dans la distribution des masses
principales qui la composent et non dans celle des espèces ni même
toujours dans celle des genres.”—“Phil. Zoologique,” chap. v.

[90] Philosophie Zoologique, première partie, chap. iii.

[91] “Entwurf einer Darstellung der zwischen dem Embryozustande
der höheren Thiere und dem permanenten der niederen stattfindenden
Parallele,” “Beyträge zur Vergleichenden Anatomie,” Bd. ii. 1811.

[92] “Origin of Species,” ed. 1, p. 457.

[93] _Ibid._ p. 458.

[94] “Origin of the Species,” p. 431.

[95] “Origin of Species,” ed. 1, p. 463.

[96] “Discours de la Méthode,” 6^e partie, Ed. Cousin, p. 193.

[97] _Ibid._ pp. 193 and 211.

[98] “De la Formation du Fœtus.”

[99] “Theoria Generationis,” 1759.

[100] “Anatomie générale,” i. p. liv.


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