The order of the outcome of the sciences in time, therefore, and their connexions with one another, cannot be explained or understood, if we look only to the sciences themselves. We must first of all descend into the depths of natural thought, or of general culture, and trace the lines which unite science with science in that general medium. The systematic interdependence of the sciences must be chiefly sought for in the workings of thought as a whole in its popular phases, and in the action and reaction of that general human thought with the sciences, those definite organisations of knowledge which form sporadically round the nuclei here and there presented in what would superficially be described as the inorganic mass and medium of popular knowledge. Thus, by means of the sciences in their aggregate action, the material of common consciousness is expanded and developed, at least in certain parts, though the expansion may be neither consistent nor systematic. But so long as this work is incomplete, so long, that is to say, as every point in the line of popular knowledge has not received its due elaboration and equal study, the sciences merely succeed each other in a certain imperfect sequence, or exist in juxtaposition: they do not form a total. The whole of scientific knowledge will only be formed, when science shall be as completely rounded and unified, as in its lower sphere and more inadequate element the ordinary consciousness of the world is now.
Up to a certain point the method of science is but the method of ordinary consciousness pursued knowingly and steadily. But ere long the method acquires a distinctive character of its own. It shakes off the pressure of that immediate subservience in which ordinary knowledge stands to man's needs, wishes and interests. Knowledge is pursued—within a wide range—for its own sake, and by a class more or less definitely set apart by humanity for its scientific service,—which is thus performed more systematically and continuously. But the great step which carries ordinary knowledge into its higher region is the discovery, due to reflection and comparison, that there is a double grade of reality-a permanent, essential, uniform, substantial being, which is contrasted with an evanescent, apparent, varying and accidental. To know a thing is in all cases to relate it to something else: to know it in the higher sense—vere scire—is to relate it to its essence, its substantial or universal form, its permanent self. Ordinary knowledge, e. g., fixes a thing by referring to its antecedents: scientific knowledge refers it to its 'invariable, 'unconditional' or 'essential' antecedent,—to something which contains it implicitly, and necessarily, and is not merely by accident or juxtaposition associated with it. To discover this permanent, underlying substance or reality comes to be the problem of science—a problem which may be taken in the widest generality, or restricted to some one group of existences. What is asked for, e.g., may be the uniformity and essence in the appearance of the diurnal journey of the sun, or it may be the underlying, invisible, nature which displays itself in all the variety of minerals, and in animal and plant life. The one-and-the-same in a diversity of many; the type-form in individuals: the cause which is the key to understanding an effect that always and unconditionally follows it; the force which finds different expression in actions—are what Science seeks.
In that search two points emerge as regards the method. The first is the importance of quantitative statements or numerical appreciations, and the general law that variations in the qualitative are in some ratio concomitant with variations in the quantitative. Mathematics, in a word, is found to be an invaluable instrument for recording with accuracy the minutest as well as the most immense differences of quality. First, it is seen that qualitative differences within a given range, e.g. various colours or various musical notes, can be accurately expressed by a numerical ratio. But, secondly, it soon appears that even greater divergences of quality, e.g. those of colour and of chemical quality, may possibly be reduced to stages on one quantitative scale. It is not unnatural that such experiences should give rise to a hope—and in sanguine minds, an assurance—that all the phenomena of nature are ultimately phases of some common nature—some elementary being—which runs through an infinite gamut of numerically defined adjustments.
But the numerical prepossession—as we may call it—creates another assumption. Every number consists of units: every cube can be regarded as an aggregation of smaller cubes, and in measurement is (implicitly at least) so regarded. Transferring this to the physical world, every object is regarded as a composite—a Large, made up by the addition and juxtaposition of many (relatively) Littles. The essentials of the composite are here the elements that compose it: these, by a natural tendency, we proceed to conceive as remaining always unchanged, and giving rise by their peculiar juxtaposition to certain perceptions in the human being. You whirl rapidly a blazing piece of wood, and instead of a discontinuous series of flashes you see one orbit of luminous matter: or, let falling rain-drops take up a particular position in reference to your eyes and the sun, and a rainbow is visible. In both cases there is what may be called an illusion—the illusion, above all, of unity and continuity. Now what is in these cases obviously and demonstrably seen, is, as Leibniz in particular has reminded us, the general law of all matter as such. In the extended and material world there is nowhere a real unity discoverable. The small is made up of the smaller ad infinitum[1]. But the conclusion (which Leibniz drew)—that unity belongs only to v,' Monads and never by any possibility to a material substance, was not that commonly reached or accepted. There are—or there must be,—said the prevalent creed, ultimates, indivisibles, indecomposables, simples, atoms. These are the final bricks of reality, out of which the apparent universe is built: each with a maximum,—a ne plus ultra—of resistibility, hardness, fullness, and unsqueezable bulk.
Into further details of these ultimate irreducibles we need not enter. It is sufficient to denote the general purport of the conception, and the tendency it implies.
In these ultimates supreme reality is understood to lie; and on them at last, and indeed always, rests whatever reality truly exists in any object. All else is secondary—and, comparatively speaking, illusory,—unreal. Any phenomena that may be noted only affect the surface or show of these reals: the inner reality continues one and unchanged. Outside them, around them, is the void—emptiness, non-entity. Yet null and void as it may be, we may, in passing, reply,—this circumambient is the source of all that gives these masses of atoms any distinctive reality—any character of true being. Space may be empty enough,—a mere spectre-shell; and yet it is their differences in spatial circumstance that bring out and actualise what they implicitly are. These 'individua' these units of reality, these atoms, are real and knowable only in their relations. So too Time may be contemptuously treated as a passive receptacle: yet it is only by its connexions in the past and the future that the present moment has any actuality it may claim. And time and space are potent agencies—in popular mode of utterance—whatever the mechanical philosophy may say.
But all of these relations are in the realm of unreality. The atoms alone are: and yet the void, which ought not to be, in an unmistakable way is also. To this mysterious vacuum which lies outside (and yet not outside) reality, to this not-being which is, there can only be given a half-negative and baffling name. Let it be called Chance—or let it be called Necessity; let it be called inexplicable Law of co-existence and sequence,—the Force which is the beginning of motion. It is the ultimate key to the mystery—but it is at least a key which no human hand can use, or even lay hold of. It is enough for science if, leaving this ultimate inexplicability untouched, it trace in each separate instance the exact equation between the sum of the constituents and the total which they compose,—if it prove that the several items when put together exactly give the sum proposed. Identification—the establishment of quantitative equations—is the work of science. Identity is its canon, working on the presumption or axiom that there can be nothing in the result which was not in the antecedents or conditions. Ex nihilo nihil fit. The quantity of energy must always be the same, though its phases may vary, or temporarily avoid detection. Matter, i.e. the ultimate reality, is indestructible. In short, the method of analysis and synthesis, as that of addition and subtraction, is a calculus which takes the form of an equation.
So far the inorganic, inanimate world has been mainly in view. If we now turn to the organisms, we find the popular creed expressed in the adage Omne vivum e vivo. No eye has ever seen—though fanatical observers have sometimes so deluded themselves as to think they saw—a living being directly emerge from inorganic stuff. The saner student of physiology contents himself with leaving for the while the crux of the genesis of Life, and examining only the building up of the living creature out of its constituents. Here the atom is called the cell: every organism is a synthesis of cells, and in the cell we have the primary element of organic reality: Omnis cellula e cellula, In the atom we have the ultimate element; in the cell a relative element,—the absolute beginning of a new order of things,—which we may, if we like, choose to treat (though only for logical simplicity's sake) as a gradual development from the other and more primitive, but which, so far as experience and history teach, is equally ultimate in its kind. But be the final constituent (physical) atom, or (physiological) cell, the relation of these constituents is at first conceived by science only as composition, or mechanical synthesis. It is only gradually that science begins to have doubts as to the inviolability and unalterableness of the elements. When the idea—not altogether new—of a 'latent meta-schematism' and latent process within the constituents is entertained and carried out in earnest, science has passed on to a new stage: from mechanical atomism to a dynamic and organic theory of existence. And the governing ideas of scientific logic have then ceased to be co-existence, and sequence, correlation and composition: the new category is intus-susception, development, adaptation not only external but internal.
Divide et impera is the motto of Science. To isolate one thing or one group of facts from its context,—to penetrate beneath the apparent simplicity, which time and custom have taught ordinary eyes to see in the concrete object, to the multitude of underlying simple elements,—to leave everything extraneous out of sight,—to abolish the teleology which imposes upon Nature a permanent tribute (direct or indirect) towards the supply of human wants,—and to take, as it were, one thing at a time and study it for itself disinterestedly; that is the problem of the sciences. And to accomplish that end they do not hesitate to break the charmed links which in common vision hold the world together,—to disregard the spiritual harmony which the sense of beauty finds in the scene,—to strip off the relations of means and end, which reflection has thrown from thing to thing, and the sensuous atmosphere of so-called 'secondary' qualities in which human sense has enveloped each; and finally to sever its connexion by which
'the whole round world is every way
Bound by gold chains about the feet of God.'