A CENTURY OF SCIENCE
And Other Essays
BY
JOHN FISKE
ε
_Out of the shadows of night
The world rolls into light:
It is daybreak everywhere._
LONGFELLOW.
BOSTON AND NEW YORK
HOUGHTON, MIFFLIN AND COMPANY
The Riverside Press, Cambridge
1899
COPYRIGHT, 1899, BY JOHN FISKE
ALL RIGHTS RESERVED
DEDICATORY EPISTLE TO THOMAS SERGEANT PERRY,
PROFESSOR OF ENGLISH LITERATURE IN THE KEIO GIJUKU, AT TOKYO.
DEAR TOM,--It has long been my wish to make you the patron saint or
tutelar divinity of some book of mine, and it has lately occurred to me
that it ought to be a book of the desultory and chatty sort that would
remind you, in your present exile at the world's eastern rim, of the
many quiet evenings of old, when, over a tankard of mellow October and
pipe of fragrant Virginia, while Yule logs crackled blithely and the
music of pattering sleet was upon the window-pane, we used to roam in
fancy through the universe and give free utterance to such thoughts,
sedate or frivolous, as seemed to us good. I dare say the present volume
may serve as an epitome of many such old-time sessions of sweet
discourse, which I trust we shall by and by repeat and renew.
But there is one link of association which in my mind especially
connects you with the present occasion. My theory of the causes and
effects of the prolongation of human infancy, with reference to the
evolution of man, was first published in the "North American Review" for
October, 1873, when you were the editor of that periodical. The article,
which was entitled "The Progress from Brute to Man," was made up of two
chapters of my "Outlines of Cosmic Philosophy" (part ii. chaps, xxi.,
xxii.), which was published a year later, in October, 1874. The value of
the theory therein set forth was at once recognized by many leading
naturalists. In the address of Vice-President Edward Morse, before the
American Association, at its meeting at Buffalo in 1876, my theory
receives extended notice as one of the most important contributions yet
made to the Doctrine of Evolution; and it is declared that I have given
"for the first time a rational explanation of the origin and persistence
of family relations, and thence communal [_i. e._, clan] relations, and,
finally, of society."[1]
Uncontrollable circumstances have prevented my giving to the further
elaboration of this infancy theory the time and attention which it
deserves and demands; but in my little book, "The Destiny of Man,"
published in 1884, I gave a popular exposition of it which has made it
widely known in all English-speaking countries and on the continent of
Europe, as well as among your worthy Japanese neighbours, Tom, who have
done me the honour to translate some of my books into their vernacular.
The theory has become still further popularized through having furnished
the starting-point for some of the most characteristic speculations of
the late Henry Drummond. In these and other ways my infancy theory has
so far entered into the current thoughts of the present age that people
have (naturally enough) begun to forget with whom it originated. For
example, in the recent book, "Through Nature to God," while criticising
a remark of Huxley's, I found it desirable to make a restatement of the
infancy theory; whereupon a friendly reviewer, referring to that
particular part of the book, observes that "of course" it makes no
pretensions to originality, but is simply my lucid summary of
speculations with which every reader of Darwin, Spencer, Huxley,
Romanes, and Drummond is familiar! In point of fact, not the faintest
suggestion of this infancy theory can be found in all the writings of
Darwin, Huxley, and Romanes. In Spencer's "Sociology," vol. i. p. 630,
it is briefly mentioned with approval as an important contribution
originating with me; and in Drummond's "Ascent of Man," which is really
built upon it, credit is cordially given me.[2]
Indeed, down to the present time, I have been left almost in exclusive
possession of that area of speculation which is occupied with the
genesis of Man as connected with that prolongation of infancy which
first began to become conspicuous in the manlike apes. There are many
who assent to what I have put forth, but few who seem inclined to enter
that difficult field on the marchland between biology, psychology, and
sociology. Doubtless this is because the attention of the scientific
world has for forty years been absorbed in the more general questions
concerning the competency of natural selection, the causes of variation,
the agencies alleged by Lamarck, and in these latter days Weismannism,
etc. In course of time, however, the more special problems connected
with man's genesis will surely come uppermost, and then we may hope to
see the causes of the lengthening of infancy investigated by thinkers
duly conversant alike with psychology and embryology.
Questions of priority in originating new theories may not greatly
interest the general reader, but you and I feel interested in preventing
any misconception in the present case; and it was thus that the careless
remark of the friendly reviewer led me to insert in the present volume
the shorthand report of some autobiographical remarks on the infancy
theory. In reading the proof-sheets I have noticed that the book
contains elsewhere many allusions to personal experiences. This feature,
which was quite unforeseen, will not fail to commend it all the more
strongly to you, my ancient friend and comrade. As for readers in
general, I may best conclude in the words of old Aaron Rathbone, whose
book entitled "The Surveyor" was dated "from my lodging at the house of
M. Roger Bvrgis, against Salisburie-house-gate, in the Strand, this sixt
of Nouember, 1616." This wise and placid philosopher saith: "To perswade
the courteous were causelesse, for they are naturally kind; and to
diswade the captious were bootless, for they will not be diverted. Let
the first make true vse of these my labours, and they shall find
pleasure and profit therein; let the last (if they like not) leave it,
and it shall not offend them."
Wherefore let me, without further ado, subscribe myself,
Ever yours,
JOHN FISKE.
CAMBRIDGE, _October 25, 1899_.
CONTENTS
PAGE
I. A CENTURY OF SCIENCE 1
II. THE DOCTRINE OF EVOLUTION: ITS SCOPE AND PURPORT 39
III. EDWARD LIVINGSTON YOUMANS 64
IV. THE PART PLAYED BY INFANCY IN THE EVOLUTION OF MAN 100
V. THE ORIGINS OF LIBERAL THOUGHT IN AMERICA 122
VI. SIR HARRY VANE 154
VII. THE ARBITRATION TREATY 166
VIII. FRANCIS PARKMAN 194
IX. EDWARD AUGUSTUS FREEMAN 265
X. CAMBRIDGE AS VILLAGE AND CITY 286
XI. A HARVEST OF IRISH FOLK-LORE 319
XII. GUESSING AT HALF AND MULTIPLYING BY TWO 333
XIII. FORTY YEARS OF BACON-SHAKESPEARE FOLLY 350
XIV. SOME CRANKS AND THEIR CROTCHETS 405
NOTE 461
INDEX 467
A CENTURY OF SCIENCE
I
A CENTURY OF SCIENCE[3]
In the course of the year 1774 Dr. Priestley found that by heating red
precipitate, or what we now call red oxide of mercury, a gas was
obtained, which he called "dephlogisticated air," or, in other words,
air deprived of phlogiston, and therefore incombustible. This
incombustible air was _oxygen_, and such was man's first introduction to
the mighty element that makes one fifth of the atmosphere in volume and
eight ninths of the ocean by weight, besides forming one half of the
earth's solid crust, and supporting all fire and all life. I know of
nothing which can reveal to us with such startling vividness the extent
of the gulf which the human mind has traversed within little more than a
hundred years. It is scarcely possible to put ourselves back into the
frame of mind in which oxygen was unknown, and no man could tell what
takes place when a log of wood is burned on the hearth. The language
employed by Dr. Priestley carries us back to the time when chemistry was
beginning to emerge from alchemy. It was Newton's contemporary, Stahl,
who invented the doctrine of phlogiston in order to account for
combustion. Stahl supposed that all combustible substances contain a
common element, or fire principle, which he called phlogiston, and which
escapes in the process of combustion. Indeed, the act of combustion was
supposed to consist in the escape of phlogiston. Whither this mysterious
fire principle betook itself, after severing its connection with visible
matter, was not too clearly indicated, but of course it was to that
limbo far larger than purgatory, the oubliette wherein have perished
men's unsuccessful guesses at truth. Stahl's theory, however, marked a
great advance upon what had gone before, inasmuch as it stated the case
in such a way as to admit of direct refutation. Little use was made of
the balance in those days, but when it was observed that zinc and lead
and sundry other substances grow heavier in burning, it seemed hardly
correct to suppose that anything had escaped from these substances. To
this objection the friends of the fire principle replied that
phlogiston might weigh less than nothing, or, in other words, might be
endowed with a positive attribute of levity, so that to subtract it from
a body would increase the weight of the body. This was a truly shifty
method of reasoning, in which your phlogiston, with its plus sign to-day
and its minus sign to-morrow, exhibited a skill in facing both ways like
that of an American candidate for public office.
Into the structure of false science that had been reared upon these
misconceptions Dr. Priestley's discovery of oxygen came like a
bombshell. As in so many other like cases, the discovery was destined to
come at about that time; it was made again three years afterward by the
Swedish chemist Scheele, without knowing what Priestley had done. The
study of oxygen soon pointed to the conclusion that, whatever may escape
during combustion, oxygen is always united with the burning substance.
Then came Lavoisier with his balance, and proved that whenever a thing
burns it combines with Priestley's oxygen, and the weight of the
resulting product is equal to the weight of the substance burned plus
the weight of oxygen abstracted from the air. Thus combustion is simply
union with oxygen, and nothing escapes. No room was left for phlogiston.
Men's thoughts were dephlogisticated from that time forth. The balance
became the ruling instrument of chemistry. One further step led to the
generalization that in all chemical changes there is no such thing as
increase or diminution, but only substitution, and upon this fundamental
truth of the indestructibility of matter all modern chemistry rests.
When we look at the stupendous edifice of science that has been reared
upon this basis, when we consider the almost limitless sweep of
inorganic and organic chemistry, the myriad applications to the arts,
the depth to which we have been enabled to penetrate into the innermost
proclivities of matter, it seems almost incredible that a single century
can have witnessed so much achievement. We must admit the fact, but our
minds cannot take it in; we are staggered by it. One thing stands out
prominently, as we contrast this rapid and coherent progress with the
barrenness of ancient alchemy and the chaotic fumbling of the Stahl
period: we see the importance of untrammelled inquiry, and of sound
methods of investigation which admit of verification at every step. That
humble instrument the balance, working in the service of sovereign law,
has been a beneficent Jinni unlocking the portals of many a chamber
wherein may be heard the secret harmonies of the world.
It is not only in chemistry, however, that the marvellous advance of
science has been exhibited. In all directions the quantity of
achievement has been so marked that it is worth our while to take a
brief general survey of the whole, to see if haply we may seize upon the
fundamental characteristics of this great progress. In the first place,
a glance at astronomy will show us how much our knowledge of the world
has enlarged in space since the day when Priestley set free his
dephlogisticated air.
The known solar system then consisted of sun, moon, earth, and the five
planets visible to the naked eye. Since the days of the Chaldæan
shepherds there had been no additions except the moons of Jupiter and
Saturn. Herschel's telescope was to win its first triumph in the
detection of Uranus in 1781. The Newtonian theory, promulgated in 1687,
had come to be generally accepted, but there were difficulties
remaining, connected with the planetary perturbations and the
inequalities in the moon's motion, which the glorious labours of
Lagrange and Laplace were presently to explain and remove,--labours
which bore their full fruition two generations later, in 1845, when the
discovery of the planet Neptune, by purely mathematical reasoning from
the observed effects of its gravitation, furnished for the Newtonian
theory the grandest confirmation known in the whole history of science.
In Priestley's time, sidereal astronomy was little more than the
cataloguing of such stars and nebulæ as could be seen with the
telescopes then at command. Sixty years after the discovery of oxygen
the distance of no star had been measured. In 1836, Auguste Comte
assured his readers that such a feat was impossible, that the Newtonian
theory could never be proved to extend through the interstellar spaces,
and that the matter of which stars are composed may be entirely
different in its properties from the matter with which we are familiar.
Within three years the first part of this prophecy was disproved when
Bessel measured the distance of the star 61 Cygni; since then the study
of the movements of double and multiple stars has shown them conforming
to Newton's law; and as for the matter of which they are composed, we
are introduced to a chapter in science which even the boldest speculator
of half a century ago would have derided as a baseless dream. The
discovery of spectrum analysis and the invention of the spectroscope,
completed in 1861 by Kirchhoff and Bunsen, have supplied data for the
creation of a stellar chemistry; showing us, for example, hydrogen in
Sirius and the nebula of Orion, sodium and potassium, calcium and iron,
in the sun; demonstrating the gaseous character of nebulæ; and revealing
chemical elements hitherto unknown, such as helium, a mineral first
detected in the sun's atmosphere, and afterward found in Norway. A still
more wonderful result of spectrum analysis is our ability to measure the
motion of a star through a slight shifting in the wave-lengths of the
light which it emits. In this way we can measure, in the absence of all
parallax, the direct approach or recession of a star; and in somewhat
similar wise has been discovered the cause of the long-observed
variations of brilliancy in Algol. That star, which is about the size of
our sun, has a dark companion not much smaller, and the twain are moving
around a third body, also dark: the result is an irregular series of
eclipses of Algol, and the gravitative forces exerted by the two
invisible stars are estimated through their effects upon the spectrum of
the bright star. In no department of science has a region of inference
been reached more remote than this. From such a flight one may come back
gently to more familiar regions while remarking upon the manifold
results that have begun to be attained from the application of a
sensitive photograph plate to the telescope in place of the human eye.
It may suffice to observe that we thus catch the fleeting aspects of
sun-spots and preserve them for study; we detect the feeble
self-luminosity still left in such a slowly cooling planet as Jupiter;
and since the metallic plate does not quickly weary, like the human
retina, the cumulative effects of its long exposure reveal the existence
of countless stars and nebulæ too remote to be otherwise reached by any
visual process. By such photographic methods George Darwin has caught an
equatorial ring in the act of detachment from its parent nebula, and the
successive phases of the slow process may be watched and recorded by
generations of mortals yet to come.
To appreciate the philosophic bearings of this vast enlargement of the
mental horizon, let us recall just what happened when Newton first took
the leap from earth into the celestial spaces by establishing a law of
physics to which moon and apple alike conform. It was the first step,
and a very long one, toward proving that the terrestrial and celestial
worlds are dynamically akin, that the same kind of order prevails
through both alike, that both are parts of one cosmic whole. So late as
Kepler's time, it was possible to argue that the planets are propelled
in their elliptic orbits by forces quite unlike any that are disclosed
by purely terrestrial experience, and therefore perhaps inaccessible to
any rational interpretation. Such imaginary lines of demarcation between
earth and heavens were forever swept away by Newton, and the recent work
of spectrum analysis simply completes the demonstration that the
remotest bodies which the photographic telescope can disclose are truly
part and parcel of the dynamic world in which we live.
All this enlargement of the mental horizon, from Newton to Kirchhoff,
had reference to space. The nineteenth century has witnessed an equally
notable enlargement with reference to time. The beginnings of scientific
geology were much later than those of astronomy. The phenomena were less
striking and far more complicated; it took longer, therefore, to bring
men's minds to bear upon them. Antagonism on the part of theologians was
also slower in dying out. The complaint against Newton, that he
substituted Blind Gravitation for an Intelligent Deity, was nothing
compared to the abuse that was afterwards lavished upon geologists for
disturbing the accepted Biblical chronology. At the time when Priestley
discovered oxygen, educated men were still to be found who could
maintain with a sober face that fossils had been created already dead
and petrified, just for the fun of the thing. The writings of Buffon
were preparing men's minds for the belief that the earth's crust has
witnessed many and important changes, but there could be no scientific
geology until further progress was made in physics and chemistry. It was
only in 1763 that Joseph Black discovered latent heat, and thus gave us
a clue to what happens when water freezes and melts, or when it is
turned into steam. It was in 1786 that the publication of James Hutton's
"Theory of the Earth" ushered in the great battle between Neptunians and
Plutonists which prepared the way for scientific geology. When the new
science won its first great triumph with Lyell in 1830, the philosophic
purport of the event was the same that was being proclaimed by the
progress of astronomy. Newton proved that the forces which keep the
planets in their orbits are not strange or supernatural forces, but just
such as we see in operation upon this earth every moment of our lives.
Geologists before Lyell had been led to the conclusion that the general
aspect of the earth's surface with which we are familiar is by no means
its primitive or its permanent aspect, but that there has been a
succession of ages, in which the relations of land and water, of
mountain and plain, have varied to a very considerable extent; in which
soils and climates have undergone most complicated vicissitudes; and in
which the earth's vegetable products and its animal populations have
again and again assumed new forms, while the old forms have passed away.
In order to account for such wholesale changes, geologists were at first
disposed to imagine violent catastrophes brought about by strange
agencies,--agencies which were perhaps not exactly supernatural, but
were in some vague, unspecified way different from those which are now
at work in the visible and familiar order of nature. But Lyell proved
that the very same kind of physical processes which are now going on
about us would suffice, during a long period of time, to produce the
changes in the inorganic world which distinguish one geological period
from another. Here, in Lyell's geological investigations, there was for
the first time due attention paid to the immense importance of the
prolonged and cumulative action of slight and unobtrusive causes. The
continual dropping that wears away stones might have served as a text
for the whole series of beautiful researches of which he first summed up
the results in 1830. As astronomy was steadily advancing toward the
proof that in the abysses of space the physical forces at work are the
same as our terrestrial forces, so geology, in carrying us back to
enormously remote periods of time, began to teach that the forces at
work have all along been the same forces that are operative now. Of
course, in that early stage when the earth's crust was in process of
formation, when the temperature was excessively high, there were
phenomena here such as can no longer be witnessed, but for which we must
look to big planets like Jupiter; in that intensely hot atmosphere
violent disturbances occur, and chemical elements are dissociated which
we are accustomed to find in close combination here. But ever since our
earth cooled to a point at which its solid crust acquired stability,
since the earliest mollusks and vertebrates began to swim in the seas
and worms to crawl in the damp ground, if at almost any time we could
have come here on a visit, we should doubtless have found things going
on at measured pace very much as at present,--here and there earthquake
and avalanche, fire and flood, but generally rain falling, sunshine
quickening, herbage sprouting, creatures of some sort browsing, all as
quiet and peaceful as a daisied field in June, without the slightest
visible presage of the continuous series of minute secular changes that
were gradually to transform a Carboniferous world into what was by and
by to be a Jurassic world, and that again into what was after a while
to be an Eocene world, and so on, until the aspect of the world that we
know to-day should noiselessly steal upon us.
When once the truth of Lyell's conclusions began to be distinctly
realized, their influence upon men's habits of thought and upon the
drift of philosophic speculation was profound. The conception of
Evolution was irresistibly forced upon men's attention. It was proved
beyond question that the world was not created in the form in which we
find it to-day, but has gone through many phases, of which the later are
very different from the earlier; and it was shown that, so far as the
inorganic world is concerned, the changes can be much more
satisfactorily explained by a reference to the ceaseless, all-pervading
activity of gentle, unobtrusive causes such as we know than by an appeal
to imaginary catastrophes such as we have no means of verifying. It
began to appear, also, that the facts which form the subject-matter of
different departments of science are not detached and independent groups
of facts, but that all are intimately related one with another, and that
all may be brought under contribution in illustrating the history of
cosmic events. It was a sense of this interdependence of different
departments that led Auguste Comte to write his "Philosophie Positive,"
the first volume of which appeared in 1830, in which he sought to point
out the methods which each science has at command for discovering truth,
and the manner in which each might be made to contribute toward a sound
body of philosophic doctrine. The attempt had a charm and a stimulus for
many minds, but failed by being enlisted in the service of sundry
sociological vagaries upon which the author's mind was completely
wrecked. "Positivism," from being the name of a potent scientific
method, became the name of one more among the myriad ways of having a
church and regulating the details of life.
While the ponderous mechanical intellect of Comte was striving to elicit
the truth from themes beyond its grasp, one of the world's supreme poets
had already discerned some of the deeper aspects of science presently to
be set forth. By temperament and by training, Goethe was one of the
first among evolutionists. The belief in an evolution of higher from
lower organisms could not fail to be strongly suggested to a mind like
his as soon as the classification of plants and animals had begun to be
conducted upon scientific principles. It is not for nothing that a table
of classes, orders, families, genera, and species, when graphically laid
out, resembles a family tree. It was not long after Linnæus that
believers in some sort of a development theory, often fantastic enough,
began to be met with. The facts of morphology gave further suggestions
in the same direction. Such facts were first generalized on a grand
scale by Goethe in his beautiful little essay on "The Metamorphoses of
Plants," written in 1790, and his "Introduction to Morphology," written
in 1795, but not published until 1807. In these profound treatises,
which were too far in advance of their age to exert much influence at
first, Goethe laid the philosophic foundations of comparative anatomy in
both vegetal and animal worlds. The conceptions of metamorphosis and of
homology, which were thus brought forward, tended powerfully toward a
recognition of the process of evolution. It was shown that what under
some circumstances grows into a stem with a whorl of leaves, under other
circumstances grows into a flower; it was shown that in the general
scheme of the vertebrate skeleton a pectoral fin, a fore leg, and a wing
occupy the same positions: thus was strongly suggested the idea that
what under some circumstances developed into a fin might under other
circumstances develop into a leg or a wing. The revelations of
palæontology, showing various extinct adult forms, with corresponding
organs in various degrees of development, went far to strengthen this
suggestion, until an unanswerable argument was reached with the study of
rudimentary organs, which have no meaning except as remnants of a
vanished past during which the organism has been changing. The study of
comparative embryology pointed in the same direction; for it was soon
observed that the embryos and larvæ of the higher forms of each group of
animals pass, "in the course of their development, through a series of
stages in which they more or less completely resemble the lower forms of
the group."[4]
Before the full significance of such facts of embryology and morphology
could be felt, it was necessary that the work of classification should
be carried far beyond the point at which it had been left by Linnæus. In
mapping out the relationships in the animal kingdom, the great Swedish
naturalist had relied less than his predecessors upon external or
superficial characteristics; the time was arriving when classification
should be based upon a thorough study of internal structure, and this
was done by a noble company of French anatomists, among whom Cuvier was
chief. It was about 1817 that Cuvier's gigantic work reached its climax
in bringing palæontology into alliance with systematic zoölogy, and
effecting that grand classification of animals in space and time which
at once cast into the shade all that had gone before it. During the past
fifty years there have been great changes made in Cuvier's
classification, especially in the case of the lower forms of animal
life. His class of _Radiata_ has been broken up, other divisions in his
invertebrate world have been modified beyond recognition, his vertebrate
scheme has been overhauled in many quarters, his attempt to erect a
distinct order for Man has been overthrown. Among the great anatomists
concerned in this work the greatest name is that of Huxley. The
classification most generally adopted to-day is Huxley's, but it is
rather a modification of Cuvier's than a new development. So enduring
has been the work of the great Frenchman.
With Cuvier the analysis of the animal organism made some progress in
such wise that anatomists began to concentrate their attention upon the
study of the development and characteristic functions of organs.
Philosophically, this was a long step in advance, but a still longer one
was taken at about the same time by that astonishing youth whose career
has no parallel in the history of science. When Xavier Bichat died in
1802, in his thirty-first year, he left behind him a treatise on
comparative anatomy in which the subject was worked up from the study
of the tissues and their properties. The path thus broken by Bichat led
to the cell doctrine of Schleiden and Schwann, matured about 1840, which
remains, with some modifications, the basis of modern biology. The
advance along these lines contributed signally to the advancement of
embryology, which reached a startling height in 1829 with the
publication of Baer's memorable treatise, in which the development of an
ovum is shown to consist in a change from homogeneity to heterogeneity
through successive differentiations. But while Baer thus arrived at the
very threshold of the law of evolution, he was not in the true sense an
evolutionist; he had nothing to say to phylogenetic evolution, or the
derivation of the higher forms of life from lower forms through physical
descent with modifications. Just so with Cuvier. When he effected his
grand classification, he prepared the way most thoroughly for a general
theory of evolution, but he always resisted any such inference from his
work. He was building better than he knew.
The hesitancy of such men as Cuvier and Baer was no doubt due partly to
the apparent absence of any true cause for physical modifications in
species, partly to the completeness with which their own great work
absorbed their minds. Often in the history of science we witness the
spectacle of a brilliant discoverer travelling in triumph along some new
path, but stopping just short of the goal which subsequent exploration
has revealed. There it stands looming up before his face, but he is
blind to its presence through the excess of light which he has already
taken in. The intellectual effort already put forth has left no surplus
for any further sweep of comprehension, so that further advance requires
a fresher mind and a new start with faculties unjaded and unwarped. To
discover a great truth usually requires a succession of thinkers. Among
the eminent anatomists who in the earlier part of our century were
occupied with the classification of animals, there were some who found
themselves compelled to believe in phylogenetic evolution, although they
could frame no satisfactory theory to account for it. The weight of
evidence was already in favour of such evolution, and these men could
not fail to see it. Foremost among them was Jean Baptiste Lamarck, whose
work was of supreme importance. His views were stated in 1809 in his
"Philosophic Zoölogique," and further illustrated in 1815, in his
voluminous treatise on invertebrate animals. Lamarck entirely rejected
the notion of special creations, and he pointed out some of the
important factors in evolution, especially the law that organs and
faculties tend to increase with exercise, and to diminish with disuse.
His weakest point was the disposition to imagine some inherent and
ubiquitous tendency toward evolution, whereas a closer study of nature
has taught us that evolution occurs only where there is a concurrence of
favourable conditions. Among others who maintained some theory of
evolution were the two Geoffroy Saint-Hilaires, father and son, and the
two great botanists, Naudin in France and Hooker in England. In 1852 the
case of evolution as against special creations was argued by Herbert
Spencer with convincing force, and in 1855 appeared "The Principles of
Psychology," by the same author, a book which is from beginning to end
an elaborate illustration of the process of evolution, and is divided
from everything that came before it by a gulf as wide as that which
divides the Copernican astronomy from the Ptolemaic.
The followers of Cuvier regarded the methods and results of these
evolutionists with strong disapproval. In the excess of such a feeling,
they even went so far as to condemn all philosophic thinking on subjects
within the scope of natural history as visionary and unscientific. Why
seek for any especial significance in the fact that every spider and
every lobster is made up of just twenty segments? Is it not enough to
know the fact? Children must not ask too many questions. It is the
business of science to gather facts, not to seek for hidden
implications. Such was the mental attitude into which men of science
were quite commonly driven, between 1830 and 1860, by their desire to
blink the question of evolution. A feeling grew up that the true glory
of a scientific career was to detect for the two hundredth time an
asteroid, or to stick a pin through a beetle with a label attached
bearing your own latinized name, _Browni_, or _Jonesii_, or
_Robinsoniense_. This feeling was especially strong in France, and was
not confined to physical science. It was exhibited a few years later in
the election of some Swedish or Norwegian naturalist (whose name I
forget) to the French Academy of Science instead of Charles Darwin: the
former had described some new kind of fly, the latter was only a
theorizer! The study of origins in particular was to be frowned upon. In
1863 the Linguistic Society of Paris passed a by-law that no
communications bearing upon the origin of language would be received. In
the same mood, Sir Henry Maine's treatise on "Ancient Law" was condemned
at a leading American university: it was enough for us to know our own
laws; those of India might interest British students who might have
occasion to go there, but not Americans. Such crude notions, utterly
hostile to the spirit of science, were unduly favoured fifty years ago
by the persistent unwillingness to submit the phenomena of organic
nature to the kind of scientific explanation which facts from all
quarters were urging upon us.
During the period from 1830 to 1860, the factor in evolution which had
hitherto escaped detection was gradually laid hold of and elaborately
studied by Charles Darwin. In the nature of his speculations, and the
occasion that called them forth, he was a true disciple of Lyell. The
work of that great geologist led directly up to Darwinism. As long as it
was supposed that each geologic period was separated from the periods
before and after it by Titanic convulsions which revolutionized the face
of the globe, it was possible for men to acquiesce in the supposition
that these convulsions wrought an abrupt and a wholesale destruction of
organic life, and that the lost forms were replaced by an equally abrupt
and wholesale supernatural creation of new forms at the beginning of
each new period. But, as people ceased to believe in the convulsions,
such an explanation began to seem improbable, and it was completely
discredited by the fact that many kinds of plants and animals have
persisted with little or no change during several successive periods,
side by side with other kinds in which there have been extensive
variation and extinction.
In connection with this a fact of great significance was elicited.
Between the fauna and flora of successive periods in the same
geographical region there is apt to be a manifest family likeness,
indicating that the later are connected with the earlier through the
bonds of physical descent. It was a case of this sort that attracted
Darwin's attention in 1835. The plants and animals of the Galapagos
Islands are either descended, with specific modifications, from those of
the mainland of Ecuador, or else there must have been an enormous number
of special creations. The case is one which at a glance presents the
notion of special creations in an absurd light. But what could have
caused the modification? What was wanted was, to be able to point to
some agency, similar to agencies now in operation, and therefore
intelligible, which could be proved to be capable of making specific
changes in plants and animals. Darwin's solution of the problem was so
beautiful, it seems now so natural and inevitable, that we may be in
danger of forgetting how complicated and abstruse the problem really
was. Starting from the known experiences of breeders of domestic animals
and cultivated plants, and duly considering the remarkable and sometimes
astonishing changes that are wrought by simple selection, the problem
was to detect among the multifarious phenomena of organic nature any
agency capable of accomplishing what man thus accomplishes by selection.
In detecting the agency of natural selection, working perpetually
through the preservation of favoured individuals and races in the
struggle for existence, Darwin found the true cause for which men were
waiting. With infinite patience and caution, he applied his method of
explanation to one group of organic phenomena after another, meeting in
every quarter with fresh and often unexpected verification. After more
than twenty years, a singular circumstance led him to publish an account
of his researches. The same group of facts had set a younger naturalist
to work upon the same problem, and a similar process of thought had led
to the same solution. Without knowing what Darwin had done, Alfred
Russel Wallace made the same discovery, and sent from the East Indies,
in 1858, his statement of it to Darwin as to the man whose judgment upon
it he should most highly prize. This made publication necessary for
Darwin. The vast treasures of theory and example which he had
accumulated were given to the world, the notion of special creations was
exploded, and the facts of phylogenetic evolution won general
acceptance.
Under the influence of this great achievement, men in every department
of science began to work in a more philosophical spirit. Naturalists,
abandoning the mood of the stamp collectors, saw in every nook and
corner some fresh illustration of Darwin's views. One serious obstacle
to any general statement of the doctrine of evolution was removed. It
was in 1861 that Herbert Spencer began to publish such a general
systematic statement. His point of departure was the point reached by
Baer in 1829, the change from homogeneity to heterogeneity. The theory
of evolution had already received in Spencer's hands a far more complete
and philosophical treatment than ever before, when the discovery of
natural selection came to supply the one feature which it lacked.
Spencer's thought is often more profound than Darwin's, but he would be
the first to admit the indispensableness of natural selection to the
successful working-out of his own theory.
The work of Spencer is beyond precedent for comprehensiveness and depth.
He began by showing that as a generalization of embryology Baer's law
needs important emendations, and he went on to prove that, as thus
rectified, the law of the development of an ovum is the law which covers
the evolution of our planetary system, and of life upon the earth's
surface in all its myriad manifestations. In Spencer's hands, the
time-honoured Nebular Theory propounded by Immanuel Kant in 1755, the
earliest of all scientific theories of evolution, took on fresh life and
meaning; and at the same time the theories of Lamarck and Darwin as to
organic evolution were worked up along with his own profound
generalization of the evolution of mind into one coherent and majestic
whole. Mankind have reason to be grateful that the promise of that
daring prospectus which so charmed and dazzled us in 1860 is at last
fulfilled; that after six-and-thirty years, despite all obstacles and
discouragements, the Master's work is virtually done.
Such a synthesis could not have been achieved, nor even attempted,
without the extraordinary expansion of molecular physics that marked the
first half of the nineteenth century. When Priestley discovered oxygen,
the undulatory theory of light, the basis of all modern physics, had not
been established. It had indeed been propounded as long ago as 1678 by
the illustrious Christian Huyghens, whom we should also remember as the
discoverer of Saturn's rings and the inventor of the pendulum clock. But
Huyghens was in advance of his age, and the overshadowing authority of
Newton, who maintained a rival hypothesis, prevented due attention being
paid to the undulatory theory until the beginning of the present
century, when it was again taken up and demonstrated by Fresnel and
Thomas Young. About the same time, our fellow countryman, Count Rumford,
was taking the lead in that series of researches which culminated in the
discovery of the mechanical equivalent of heat by Dr. Joule in 1843. One
of Priestley's earliest books, the one which made him a doctor of laws
and a fellow of the Royal Society, was a treatise on electricity,
published in 1767. It was a long step from that book to the one in which
the Danish physicist Oersted, in 1820, demonstrated the intimate
correlation between electricity and magnetism, thus preparing the way
for Faraday's great discovery of magneto-electric induction in 1831. By
the middle of our century the work in these various departments of
physics had led to the detection of the deepest truth in science,--the
law of correlation and conservation, which we owe chiefly to Helmholtz,
Mayer, and Grove. It was proved that light and heat, and the
manifestations of force which we group together under the name of
electricity, are various modes of undulatory motion transformable one
into another; and that, in the operations of nature, energy is never
annihilated, but only changed from one form into another. This
generalization includes the indestructibility of matter, and thus lies
at the bottom of all chemistry and physics and of all science.
Returning to that chemistry with which we started, we may recall two
laws that were propounded early in the century, one of which was
instantly adopted, while the other had to wait for its day. Dalton's law
of definite and multiple proportions has been ever since 1808 the corner
stone of chemical science, and the atomic theory by which he sought to
explain the law has exercised a profound influence upon all modern
speculation. The other law, announced by Avogadro in 1811, that, "under
the same conditions of pressure and temperature, equal volumes of all
gaseous substances, whether elementary or compound, contain the same
number of molecules," was neglected for nearly fifty years, and then,
when it was taken up and applied, it remodelled the whole science of
chemistry, and threw a flood of light upon the internal constitution of
matter. In this direction a new world of speculation is opening up
before us, full of wondrous charm. The amazing progress made since
Priestley's day may be summed up in a single contrast. In 1781 Cavendish
ascertained the bare fact that water is made up of oxygen and hydrogen;
within ninety years from that time Sir William Thomson was able to tell
us that "if the drop of water were magnified to the size of the earth,
the constituent atoms would be larger than peas, but not so large as
billiard balls." Such a statement is confessedly provisional, but,
allowing for this, the contrast is no less striking.
Concerning the various and complicated applications of physical science
to the arts, by which human life has been so profoundly affected in the
present century, a mere catalogue of them would tax our attention to
little purpose. As my object in the present sketch is simply to trace
the broad outlines of advance in pure science, I pass over these
applications, merely observing that the perpetual interaction between
theory and practice is such that each new invention is liable to modify
the science in which it originated, either by encountering fresh
questions or by suggesting new methods, or in both these ways. The work
of men like Pasteur and Koch cannot fail to influence biological theory
as much as medical practice. The practical uses of electricity are
introducing new features into the whole subject of molecular physics,
and in this region, I suspect, we are to look for some of the most
striking disclosures of the immediate future.
A word must be said of the historical sciences, which have witnessed as
great changes as any others, mainly through the introduction of the
comparative method of inquiry. The first two great triumphs of the
comparative method were achieved contemporaneously in two fields of
inquiry very remote from one another: the one was the work of Cuvier,
above mentioned; the other was the founding of the comparative philology
of the Aryan languages by Franz Bopp, in 1816. The work of Bopp exerted
as powerful an influence throughout all the historical fields of study
as Cuvier exerted in biology. The young men whose minds were receiving
their formative impulses between 1825 and 1840, under the various
influences of Cuvier and Saint-Hilaire, Lyell, Goethe, Bopp, and other
such great leaders, began themselves to come to the foreground as
leaders of thought about 1860: on the one hand, such men as Darwin,
Gray, Huxley, and Wallace; on the other hand, such as Kuhn and
Schleicher, Maine, Maurer, Mommsen, Freeman, and Tylor. The point of
the comparative method, in whatever field it may be applied, is that it
brings before us a great number of objects so nearly alike that we are
bound to assume for them an origin and general history in common, while
at the same time they present such differences in detail as to suggest
that some have advanced further than others in the direction in which
all are travelling; some, again, have been abruptly arrested, others
perhaps even turned aside from the path. In the attempt to classify such
phenomena, whether in the historical or in the physical sciences, the
conception of development is presented to the student with irresistible
force. In the case of the Aryan languages, no one would think of
doubting their descent from a common original: just side by side is the
parallel case of one sub-group of the Aryan languages, namely, the seven
Romance languages which we know to have been developed out of Latin
since the Christian era. In these cases we can study the process of
change resulting in forms that are more or less divergent from their
originals. In one quarter a form is retained with little modification;
in another it is completely blurred, as the Latin _metipsissimus_
becomes _medesimo_ in Italian, but _mismo_ in Spanish, while in modern
French there is nothing left of it but _même_. So in Sanskrit and in
Lithuanian we find a most ingenious and elaborate system of conjugation
and declension, which in such languages as Greek and Latin is more or
less curtailed and altered, and which in English is almost completely
lost. Yet in Old English there are quite enough vestiges of the system
to enable us to identify it with the Lithuanian and Sanskrit.