THE MECHANICAL THEORY OF EVOLUTION: THE DARWIN-WEISMANN EXPLANATION
“Chance guides all things: mind and forethought must call it God
alone!”—Menander.
“In the end,” writes M. Edmond Perrier, “every imaginable theory of
evolution must lead up to one or other of two absolute doctrines,
essentially antagonistic to each other. Either the inheritance
of acquired characteristics must be admitted in its full scope
(_dans toute sa généralité_), or else we must believe in the
predestination of protoplasm, developing by virtue of its own
internal forces. But in the latter case we pass from the domain of
pure science to enter that of metaphysics.”[66]
We have now to consider the most conspicuous attempt made in recent
times to escape from this tragic dilemma.
If the acquired and inherited variations of the Lamarckian theory drop
out as a contribution to the explanation of evolution, we are reduced
to two forces only—_innate_, or germinal, variability of offspring,
and natural selection. Indeed it might be said that we are reduced
to variability alone, since natural selection can do nothing until
suitable variations are presented to it. The suitable variations do,
however, turn up, and the question is, what causes them? The real
difficulty for the school of biologists who, like Weismann, “assume
the mechanical theory of the world to be correct,” is how to reconcile
the aptness and apparent purposefulness of these variations with any
mechanical theory.
“We are justified in inquiring,” writes Weismann, “whether the
assumption of ‘chance’ germinal variations, which we have hitherto
made with Darwin and Wallace, affords a sufficient basis for
selection. Osborn says very neatly in this connection, ‘We see with
Weismann and Galton the element of chance; but the dice appear to
be loaded, and in the long run turn “sixes” up. Here arises the
question, What loads the dice?’”[67]
What loads the dice? There is the great question in which the realms of
biology and of philosophy meet each other! Through that borderland no
definite frontier has ever been traced, for in thought as in matter the
saying is true that natural groupings have nuclei, but no boundaries.
It is all the more essential that men of science should understand
philosophy and its methods, and that philosophers should understand
science. It is to be feared that at present the second of these
desiderata is much more fully realized than the first.
However, we have to see now what Weismann, protagonist among
contemporary biologists of the mechanical theory of the world, has to
answer to the crucial question which he has allowed Osborn to set him.
The problem is to discover how innate, germinal variations can come
about, of such a nature as to adapt an organism with striking accuracy
to its surroundings and way of life, without our assuming either (1)
that the exercise of function had any influence in causing heritable
variations, or (2) that they were caused by any non-mechanical power,
which, so to speak, had in view the objects which they fulfil. For
the variations are to be regarded, on Weismann’s theory of life, as
completely _fortuitous_ in respect of the objects they serve. How,
then, do they come to serve them, in most cases, so admirably well?
The general nature of Weismann’s explanation may be summed up in a
curious illustration given by him in The Evolution Theory.[68] Let
us suppose, he says, a snow-field surrounded by precipices on all
sides, but with a narrow track leading away from it at one point.
Scattered about on the snow-field are a number of persons. A sleigh is
now projected among them from some outside point. Each person, when
the sleigh comes near him, gives it a push, but he has no object in
pushing it anywhere in particular, and simply sends it flying off in
whatever direction he chances to be looking. What will happen under
these circumstances? After more or less bandying about, the sleigh
will, in the vast majority of cases, fall into one of the abysses round
the snow-field and be lost But another is then launched on to the
snow-field, and then another and another without end; and so, at last,
it may happen that a series of pushes will take place which will send
the sleigh over the narrow track to its goal.
The goal is supposed to represent some condition to which the
organism (the sleigh) has to adapt itself. The random pushes which
it receives are the multitude of variations constantly occurring in
the reproductive cells. Most of these variations have no decisive
tendency, favourable or unfavourable. If a series of unfavourable
ones should occur, leading to some development which markedly impairs
the chances of the organism for success in life, it, or its line of
succession, dies out, and the unfavourable variation is, therefore, not
perpetuated. This is illustrated by the sleigh going into the abyss.
But if a favourable variation occurs, and is increased till it reaches
‘selection value,’ _i.e._ till it gives the organisms possessing it
a distinct advantage over others in the battle of life, then this
favoured type will ultimately, by the action of natural selection,
drive out the less favoured, and will establish itself as the sole
representative of the species. Having reached this level, of course the
same process will go on further indefinitely.
Before criticizing this conception of evolutionary processes, we
must inquire into the vital point of how the variations, the random
pushes given to the sleighs, ever rise to such intensity as to
have selection-value, and to make head against the influence of
intercrossing. The explanation is certainly ingenious, but is so purely
hypothetical and has an air so fantastic that it has commended itself
to very few students of biology. Weismann would have us suppose that
the determinants of which the hereditary substance in the reproductive
cells is made up are carrying on with each other an incessant struggle
for nutriment. If one of them succeeds in getting a little more than
its neighbours it thereby grows stronger, and is able to attract
still more nutriment to itself, and to impoverish those around it. It
is thus launched, as it were, on an ascending scale, and will go on
automatically if the variation caused by it proves favourable to the
species. If it proves unfavourable (which _ex hypothesi_ it is just
as likely to do) its career will be put a stop to by the extinction
of the line of descent which inherits this variation. Weismann’s
theory of “Germinal Selection” is therefore simply an application to
the reproductive cell and its contents of the Darwinian principle of
Natural Selection.
The theory is one which plainly makes immense demands upon our
faith. As regards the existence of a continual competition among
the determinants, there may be reason to accept it, but hardly in
the Weismann sense. Suppose two parents to unite, one healthy,
well-nourished, full-blooded, the other starved and weakly, it is
very likely that, in the resulting offspring, other things being
equal, the determinants coming from the well-nourished frame will be
seen to have surpassed in potency those from the weakly one. For the
determinants are living protoplasm—they depend on nourishment derived
from the blood of the organism in which they are lodged, and they
are capable, no doubt, of being well-nourished or ill-nourished or
possibly over-nourished, according to the constitution and history of
that organism. But this is a very different thing from supposing that
one determinant can begin to grow in _the same cell_ at the expense
of another, when both are absolutely embedded in an ocean of the same
nutritive matter. There is not—of course in the nature of things
there cannot be—a particle of evidence for the supposition. It is a
pure imaginative hypothesis, and on the face of it a most improbable
one. It is difficult to believe that it could ever have been adopted
save as a desperate attempt to break through the ever-narrowing ring
of evidence which is forcing investigation more and more towards a
non-mechanical explanation of the processes of life. But even if it
were true, what is gained by it? “Appropriate variational tendencies,”
writes Weismann, “not only _may_ present themselves, they _must_ do so,
if the germ-plasm contains determinants at all by whose fluctuations in
a plus or minus direction the appropriate variation is attainable.”[69]
But why _must_ they? There is no ‘must’ about Chance, unless one
extends its operations to infinity. Why is it so certain that the
inequalities of nutriment, on which hereditary variability is supposed
to depend, must necessarily run the gamut of all possible variations?
There is no ‘must’ in this theory, except that it is the last ditch
of the “mechanical conception of the economy of life.” It ‘must’ be
true—or that conception must quit the field.
Were evolution to depend on the occurrence, by pure chance, of a
few appropriate variations among a vast multitude of indifferent or
disadvantageous ones, is it conceivable that we should find in nature
anything like the infinite wealth of closely and beautifully adapted
structure which is actually present? In particular, how are we to
account for the cases in which a number of parts are so modified as
to work together in harmonious co-adaptation? Each of these parts,
according to Weismann, originates quite independently of the others.
Take the case of the Indian leaf-butterfly already referred to.[70]
The first beginnings of the midrib on Weismann’s theory had nothing to
do with the rest of the rib, nor had any of the veinings with this, or
with one another; and the contour of the leaf, sending out a little
projection like a stalk _exactly where the midrib starts_, originated
quite independently of that marking, and equally so of the leaf it
mimics! To explain co-adaptations like this on Weismann’s theory is
really much the same as to suppose that a picture could be painted by
simply plastering the scrapings of a palette on a canvas, if only one
continued the process long enough. And the marvel in question, the
co-adaptation of various parts, has not been attained once or twice
but, to a greater or less degree, in _every_ organism possessing any
structural complexity.
The difficulty, of course, has not escaped Weismann. His explanation
depends on some conception of the potentialities of conjugation and
intercrossing which I confess I cannot understand. He finds the key to
the mystery in the mingling and constant recombination of determinants
from different individuals produced by promiscuous intercrossing. “It
is only through amphimixis [conjugation] that simultaneous harmonious
adaptation of many parts becomes possible.”[71] But surely this
continual mingling and recombination would, _primâ facie_, be just as
likely to break up co-adaptations already forming as to give rise to
new ones? Amphimixis, as we have seen, is one of the most potent forces
against which the evolution of a new species has to contend. Evolution
has to make head against the constant tendency of intercrossing to
obliterate individual distinctions. True, if parents exhibiting
the same heritable variation unite, their offspring will have that
variation in a strongly marked form, and will transmit it further. But
this, to be of value for evolution, presupposes the same variation
occurring simultaneously in a number of individuals within reach of
each other. Weismann had indeed good reason to ascribe to the action of
intercrossing “a wealth and diversity of organic architecture otherwise
unattainable,” but were it not supplemented by an architectural
instinct of nature, the only architecture attainable would be that of
the child when it empties its bricks on the floor.
Consider the theory of germinal selection in the light of the following
very curious case.[72] Most people have seen an example of the kind
of spectacles having what are called bifocal lenses. Each lens is
divided across the centre, and the focal lengths of the upper and
the lower halves are different. They are intended for persons who see
indistinctly both at near and at far distances—the upper half of the
lens is used for looking at distant objects and the lower for reading,
etc., so as to avoid the inconvenience of having a different pair of
glasses for each requirement. Now there is a fish, named _Anableps_
(the Uplooker), living in estuaries on the east coast of South America
which actually has its eye-lenses constructed on this principle. The
pupil of the eye is divided laterally by prolongations from the iris.
The significance of this extraordinary arrangement is that the fish
is in the habit of swimming near the surface, and often has its eyes
wholly or partly out of water, presumably to look out for attacks from
birds of prey. The upper half of the eye has become adapted for vision
in the air and the lower for vision in the water.
According to Weismann, the habits and needs of the fish could have
had no influence whatever in producing this peculiar adaptation as an
inherited characteristic of a species. Any other fish or mammal would
have been just as likely as _Anableps_ to begin the development of a
bifocal eye. How does it come, then, that from the thousands of species
of eyed animals one, and one only, possesses this bifocal eye, and that
precisely the one which so greatly needs it? Weismann’s answer would
doubtless be that, in the case of other creatures, Natural Selection
would not have acted in protecting the individuals which possessed
the bifocal eye and penalizing those which did not. But can we imagine
that this principle acted very strongly when the bifocal arrangement
in _Anableps_ was in a mere rudimentary stage, as it must at first
have been? And should we not occasionally see at least traces of the
arrangement in the eyes of other creatures, if its full development in
_Anableps_ was merely the result of Natural Selection laying hold of
and perfecting an originally quite fortuitous variation?
A case still more curious and convincing occurs in connexion with
the hermaphroditism exhibited by a whole class of animals belonging
to many different orders, but alike in the one respect that it is
specially desirable for them to have both sexes comprised in the same
individual. These are animals capable only of sluggish movement, the
different sexes of which have therefore some difficulty in finding
each other out. Terrestrial snails and slugs are an example. All these
creatures are double-sexed; any two snails which meet can conjugate,
since each can act either as male or as female at will. Oysters are
another instance, though in this case the two sexes follow each other
at different periods in the life-history of each individual. Clearly,
this faculty gives to snails and slugs twice as many opportunities of
reproducing their kind as if the sexes were distinct. It is certain
from general biological considerations that they were distinct
originally. One can easily understand how, if any small group of the
original species from which all the present tribes are descended,
happened to throw up these bisexual peculiarities, their progeny would
multiply faster than the rest and might ultimately exterminate them
by the operation of natural selection. _But exactly the same might be
said of any other tribe of unisexual animals._ Any of these might,
_a priori_, on the “mechanical conception of the economy of life,”
be just as reasonably expected to develop bisexuality; for no one
supposes that there is any physical connexion between sluggishness
and hermaphroditism, or swiftness and distinction of the sexes; and
the causes which have operated to extend and confirm the type in
sluggish and sedentary animals would have the same effect in swift
ones. Yet this remarkable adaptation occurs just wherever there is
special need for it; there always and there only. What mechanism can
account for such a phenomenon as this? No; the dice are loaded. Nature
gains her end slowly and not without hesitations and failures, but the
phenomena are wholly unlike the results of the play of uncontrolled
and fortuitous forces. Imagine a blindfolded archer shooting arrows
upwards, downwards, and all around him in every direction as it may
take his fancy. There is, unknown to him, a target some distance
off. If he went on long enough it is conceivable, though by no means
necessary, that some arrow would hit the bull’s eye. But the facts
plainly point not to the above analogy, but rather to an aim at a
desired object. Some of the arrows miss, some light near the mark,
others hit it precisely. The flight, on the whole, is in the right
direction, as the immense proportion of complete or partial successes
plainly proves.
The two pillars of Weismann’s theory of evolution are _germinal
variation_ and _natural selection_. The one is supposed to originate
ceaseless changes of structure, the other to eliminate those changes
which are useless[73] or unfavourable and to foster and confirm the
favourable. We have seen, if the foregoing considerations are sound,
that fortuitous variations do not provide the material with which
natural selection can build up a universe of organic life like ours. We
have now to turn our attention to the other prop of the system and to
inquire whether natural selection can play and does play the part which
Darwin and his school assign to it in the economy of nature.
Natural selection is supposed to depend for its efficacy on the
existence of a state of strenuous competition for nourishment, or
for the avoidance of foes, in the type out of which the favourable
variations emerge. But in recent times the fact of any such
competition has been gravely doubted. Let us look back to the
beginnings of animal life in the world. The first primitive animal
organisms found themselves swimming in a boundless sea of nourishment
and had no foes at all! Yet they developed into higher and higher
grades of life. Competition did not aid in the development of these
higher grades—it was they which ultimately created the state of
competition. What Nature then achieved without competition she is
equally able to perform now. Even now when the earth is swarming with
varied life competition plays a much smaller part than was taken for
granted in the first flush of Darwinism. Creatures of the same type but
on different grades of organization, like the hive-bee and the humble
bee, are constantly found side by side, drawing their nourishment
from the same sources, but each holding its own without difficulty.
Facts like these were not unobserved by Darwin, who met them by the
supposition that competition came chiefly into play at exceptional
periods, during a drought, an inundation, a severe winter, or the like,
in which the less fitted members of the race perished wholesale. But,
as Kropotkin, in his interesting work, Mutual Aid among Animals, has
remarked,
“If the evolution of the animal world were based exclusively, or
even chiefly, upon the survival of the fittest during periods of
calamities; if natural selection were limited in its action to
periods of exceptional drought, or sudden changes of temperature,
or inundations, retrogression would be the rule in the animal
world. Those who survive a famine, or a severe epidemic of cholera,
or small-pox, or diphtheria, such as we see them in uncivilized
countries, are neither the strongest, nor the healthiest, nor the
most intelligent. No progress could be based on such survivals—the
less so as all survivors usually come out of the ordeal with an
impaired health, like the Transbaikalian horses just mentioned,
or the Arctic crews, or the garrison of a fortress which has been
compelled to live for a few months on half rations, and comes out
of its experience with a broken health, and subsequently shows a
quite abnormal mortality.”[74]
Kropotkin’s book shows good reason to believe that the principle of
mutual aid and support plays at least as great a part in the animal
world as does that of mutual competition and extermination.
That the competition of organisms, animal and vegetable, for
nourishment and for protection may favour certain types, and depress or
even exterminate others, is of course indisputable. We see it when the
Japanese worker and the Californian meet in industrial rivalry on the
Pacific slopes—we see it when the willows planted by New Zealand rivers
destroy the weed which infested them, by absorbing the nourishment
from the river-bed on which it lived.[75] What we have to consider,
however, is the efficacy of competition in giving predominance and
permanence to a type differing but slightly in the initial stages
from that of the rest of the species, and differing but in a very few
individuals. We have to consider, in fact, whether natural selection is
not a consequence rather than a cause of evolution. On no mechanical
theory of evolution can we suppose that the first leaf-markings of the
butterfly, _Kallima paralecta_, were either at all pronounced in their
mimicry, or that they originated simultaneously in any large group of
the original species from which _Kallima paralecta_ sprang. Therefore,
with very small advantage in the way of protection from enemies, and
with the constant and powerful influence of intercrossing ever tending
to obliterate the distinctive leaf-marks, how could natural selection
alone enable the new, the mimicking type, to assert and develop itself,
as it has done not only in this particular species of butterfly but in
hundreds of species of the _Lepidoptera_ and other insects?
“A considerable initial resemblance,” writes Mr. Beddard in his
most valuable though somewhat chaotic work on this subject,[76]
“may be fairly set down to other causes [than natural selection];
because it is impossible to believe that a slight move in the
required direction would be of sufficient importance to serve as
material for the action of natural elimination.”
The most convinced Darwinian will hardly deny that the problem involved
in this case is a serious one.
Another singular fact to be noted in this connexion is the “conclusion
arrived at by the study of mimetic butterflies in all parts of the
world—that the females are far more liable to assume this method of
defence than the males.”[77] An instance in point, which has been
the subject of much discussion, is that of the yellow and black
swallow-tailed butterfly, _Papilio meriones_, found in Madagascar.
The island is supposed to be the original home of the species, and
here both sexes are much alike. On the mainland of South Africa,
however, while the male has undergone the very slight transformations
represented by the species _P. merope_ and _P. cenea_, the females
imitate closely three different species of the _Danais_ butterfly
which is protected by its disagreeable taste from the usual enemies of
the tribe, and which is altogether unlike in shape and coloration to
the swallow-tail. “The new forms,” writes Mr. Poulton, “have arisen
at so recent a date that many of the intermediate stages can still be
seen, while the parent form has been preserved unchanged in a friendly
land, where the keener struggle of continental areas is unknown.”[78]
The significance of such a fact as this is obvious. If mimicry arose
from fortuitous variations of colouring and of form, males alone
might show it in some species, females alone in others, and both in
yet others, but it is difficult to understand how we could arrive
at the actual condition, and find it either common to both sexes or
practically confined to the female. If, on the other hand, mimicry
and other similar adaptations are ultimately to be interpreted as the
common response of the species to the attack of its foes, it is quite
natural that the female, as the egg-bearer, the most important factor
in the continuance of the species, should be specially protected. It is
probable also that she is most in need of protection, as her functions
may render her rather more exposed than the male to attack. That
natural selection cannot have been the dominant factor in the case we
are considering seems clear; for how could it have acted at all without
a somewhat vigorous weeding out of unprotected forms? And, in that
case, what would have become of the unprotected males of the species?
Difficulties of this kind have, in different cases, been raised again
and again since the publication of the Origin of Species, and have had
to be answered so often that there seems good _prima facie_ ground
for doubting whether they have ever really been answered at all. The
strongest advocates of the pure mechanical theory are obliged, as we
have seen, to admit that the drift of contemporary scientific opinion
is to place little reliance on casual variation and natural selection
and to look for the driving force of evolution in other directions.[79]
In the introduction to Strasburger’s Text Book of Botany[80] we find
this important passage:—
“The tendency is to assume the existence of a development of
the organic world due to original, innate capabilities of the
living substance and not dependent on selection. The origin of
the large subdivisions of the animal and vegetable kingdoms,
the ‘Archetypes,’ would be due to this sort of evolution. These
archetypes have been, and are still, continually influenced by
the environment, and, by their reaction to external conditions,
organisms become more or less directly adapted.... The progressive
evolution of the archetypes, as well as the direct adaptations to
external conditions shown by them, is independent of selection.
The latter does, however, exert an influence on the process of
evolution of the organic world, though to a much more limited
extent than was formerly supposed.”
It is clear that in these _original innate capabilities of the living
substance_ we have a power which alone _may_ fully account for the
evolution of the organic world, though natural selection can emphasize
and hasten its action. Its nature and limits are still undetermined.
Biologists are very chary of expressing this power save in terms of
chemistry and physics. Men of science are afraid—sometimes I venture to
think even morbidly afraid—of opening any door by which the fantastic
horde of arbitrary dogmas and superstitions which they have cast out
with so much toil and peril might find their way back into the temple
of Knowledge. But philosophy must warn them that in shutting out
all forces that cannot be weighed and measured in a laboratory they
may be shutting out life itself. And those who strenuously insist on
reducing nature to a mechanism often find themselves obliged to let
in the mysterious life-force by some more or less clandestine entry
in order to make their mechanism work. Thus Nägeli, the originator
of the theory of heredity which Weismann has developed, attributes
the phenomena of growth and evolution not to natural selection but
to “internal forces.”[81] He disclaims for these forces any but a
physical and chemical significance; but Professor Eimer, in spite of
all disclaimers, cannot get rid of the suspicion, well justified in
my opinion, that there is in these forces, as conceived by Nägeli,
something purposeful and teleological—admit them, he says in effect,
and who knows what we shall next be asked to believe?[82] Yet for Eimer
himself we find that, as Schopenhauer says, “the lotus of physics
is rooted in metaphysics.” Twice in his work on organic evolution,
he refers with approval to the view of “our profound philosopher,
Oken,”[83] who regarded all existing beings as members or organs of
some vast and transcendental organism whose development conditioned
theirs. Eimer even makes a somewhat daring application of this
principle to a concrete instance in the physical world, one which we
have already referred to, the problem of the inheritance of qualities
in ants, bees, etc., when these qualities are possessed and exercised
only by individuals who cannot transmit them.
“We must regard,” he writes, “the different forms of bees, queens,
drones, workers, as _discontinuous organs of one whole_, which have
been evolved from a single indifferent ancestral form.... Only
thus can we explain to ourselves the fact that the peculiarities
of the workers, notwithstanding that they do not reproduce, are
inherited.”[84]
When we are asked to believe in physico-chemical laws of such a
nature that they enable the habits of life of a worker-ant or bee to
react upon the germ-cells of the queen, just as the exercise of an
organ, on Lamarckian principles, affects the reproductive cells of
the creature to which it belongs, it becomes plain enough that for
modern investigators the so-called mechanical and the so-called psychic
conceptions of the universe are really running out at the same point.
The gulf between these conceptions, which seemed to yawn so widely
after Darwinism, was a mere illusion, arising from a point of view now
left behind.
To resume the argument of the foregoing chapters. We have seen that at
the basis of all theories of evolution lies the fact of the responsive
powers of living protoplasm. _But what does it respond to?_ That is the
question of questions. To put it accurately in relation to the process
of evolution we must ask, To what do the determinants in the germinal
cells of plants and animals respond? To what call did unicellular
organisms respond when they first began to interchange chromatin with
each other? To what, when they began to divide and form new organisms?
To what, when multicellular organisms began to specialize certain cells
for reproduction, and these cells to mature themselves for fusion by
throwing out half their chromosomes? And when the higher plants and
animals came on the scene, reproducing their kind under conditions
which make strongly for the fixity of species, how are we to interpret
the response of protoplasm when we see organs and structures melt away,
and others grow, giving rise to the innumerable types which yield us
the existing world with its overwhelming richness and variety of life?
Weismann tells us that the response is only to differences in the
amount of nutriment obtainable by the various determinants of the germ
cell, and has but a fortuitous connexion with the results attained.
We have seen the inadequacy of this theory, in the light of the many
adaptations such as that of which the fish, _Anableps_, with its
bifocal eyes, and the double sexual organs of terrestrial snails, are
types. Lamarck and Darwin, besides the belief in fortuitous variation,
held that heritable characters arise from exercise of function.
Innumerable cases can be quoted in favour of this explanation, but
we have seen instances in which it is absolutely untenable, and yet
where the required response takes place just the same. The influence
of light and colour tells on the colouring of animals, and impartially
protects them when they are preyed upon, or helps them to secure their
prey; and this influence is frequently explainable by chemical or
electric agencies originating in the environment of the animal, acting
on the blood, and thus influencing pigmentation of the skin,[85] but
chemistry is helpless to account for the manner in which nature shapes
the contour of the wing of a tropical butterfly and paints upon it
the veinings of a leaf, or protects a harmless fly by giving it a
resemblance to a stinging one, or protects a caterpillar by making it
look like a vicious and dangerous reptile. Yet all these protective
arrangements are evidently, at bottom, facts of the same order.
Protoplasm lives and responds not only discretely in the lowest unit
perceptible by the microscope, but collectively in the connected groups
of these units called multicellular organisms, and in the disconnected
groups of these organisms called species. It really responds not to the
exercise of function or to the play of physical forces, but to vital
tendencies of the organism. There seems an expansive force in nature
which, though working strictly under the dominion of physical laws, is
capable of using the combinations brought about by those laws for the
preservation and development of life. It is in love with life, it is
ever pressing toward action and self-realization, and all roads are one
to it if they lead to that end. In it are included the very chemical
and physical agencies which it obeys, and also that something beyond
which eludes the analysis of the laboratory.
How it acts, under what conditions, what limitations, why here in one
way, there in another, are questions of profound interest, the fringe
of which philosophy has hardly begun to touch. Nor is philosophy yet
in a position to do more, for the scientific conception of nature is
but a recent birth of thought; much remains to do in the collection and
organization of the facts with which the framework must be filled in,
and a philosophy which does not keep closely in touch with scientific
fact can have no message for the modern world. But it does seem
possible to discern, and it shall now be our endeavour to set forth,
in broad outline, certain principles of deep significance from which
we may obtain an answer to the question: What can we learn from the
physical universe that has a bearing on the spiritual life of man?