SECOND BOOK. THE WORLD AS WILL.
FIRST ASPECT.
THE OBJECTIFICATION OF THE WILL.
Nos habitat, non tartara, sed nec sidera coeli:
Spiritus, in nobis qui viget, illa facit.
§ 17. In the first book we considered the idea merely as such, that is, only according to its general form. It is true that as far as the abstract idea, the concept, is concerned, we obtained a knowledge of it in respect of its content also, because it has content and meaning only in relation to the idea of perception, without which it would be worthless and empty. Accordingly, directing our attention exclusively to the idea of perception, we shall now endeavour to arrive at a knowledge of its content, its more exact definition, and the forms which it presents to us. And it will specially interest us to find an explanation of its peculiar significance, that significance which is otherwise merely felt, but on account of which it is that these pictures do not pass by us entirely strange and meaningless, as they must otherwise do, but speak to us directly, are understood, and obtain an interest which concerns our whole nature.
We direct our attention to mathematics, natural science, and philosophy, for each of these holds out the hope that it will afford us a part of the explanation we desire. Now, taking philosophy first, we find that it is like a monster with many heads, each of which speaks a different language. They are not, indeed, all at variance on the point we are here considering, the significance of the idea of perception. For, with the exception of the Sceptics and the Idealists, the others, for the most part, speak very much in the same way of an object which constitutes the basis of the idea, and which is indeed different in its whole being and nature from the idea, but yet is in all points as like it as one egg is to another. But this does not help us, for we are quite unable to distinguish such an object from the idea; we find that they are one and the same; for every object always and for ever presupposes a subject, and therefore remains idea, so that we recognised objectivity as belonging to the most universal form of the idea, which is the division into subject and object. Further, the principle of sufficient reason, which is referred to in support of this doctrine, is for us merely the form of the idea, the orderly combination of one idea with another, but not the combination of the whole finite or infinite series of ideas with something which is not idea at all, and which cannot therefore be presented in perception. Of the Sceptics and Idealists we spoke above, in examining the controversy about the reality of the outer world.
If we turn to mathematics to look for the fuller knowledge we desire of the idea of perception, which we have, as yet, only understood generally, merely in its form, we find that mathematics only treats of these ideas so far as they fill time and space, that is, so far as they are quantities. It will tell us with the greatest accuracy the how-many and the how-much; but as this is always merely relative, that is to say, merely a comparison of one idea with others, and a comparison only in the one respect of quantity, this also is not the information we are principally in search of.
Lastly, if we turn to the wide province of natural science, which is divided into many fields, we may, in the first place, make a general division of it into two parts. It is either the description of forms, which I call Morphology, or the explanation of changes, which I call Etiology. The first treats of the permanent forms, the second of the changing matter, according to the laws of its transition from one form to another. The first is the whole extent of what is generally called natural history. It teaches us, especially in the sciences of botany and zoology, the various permanent, organised, and therefore definitely determined forms in the constant change of individuals; and these forms constitute a great part of the content of the idea of perception. In natural history they are classified, separated, united, arranged according to natural and artificial systems, and brought under concepts which make a general view and knowledge of the whole of them possible. Further, an infinitely fine analogy both in the whole and in the parts of these forms, and running through them all (unité de plan), is established, and thus they may be compared to innumerable variations on a theme which is not given. The passage of matter into these forms, that is to say, the origin of individuals, is not a special part of natural science, for every individual springs from its like by generation, which is everywhere equally mysterious, and has as yet evaded definite knowledge. The little that is known on the subject finds its place in physiology, which belongs to that part of natural science I have called etiology. Mineralogy also, especially where it becomes geology, inclines towards etiology, though it principally belongs to morphology. Etiology proper comprehends all those branches of natural science in which the chief concern is the knowledge of cause and effect. The sciences teach how, according to an invariable rule, one condition of matter is necessarily followed by a certain other condition; how one change necessarily conditions and brings about a certain other change; this sort of teaching is called explanation. The principal sciences in this department are mechanics, physics, chemistry, and physiology.
If, however, we surrender ourselves to its teaching, we soon become convinced that etiology cannot afford us the information we chiefly desire, any more than morphology. The latter presents to us innumerable and infinitely varied forms, which are yet related by an unmistakable family likeness. These are for us ideas, and when only treated in this way, they remain always strange to us, and stand before us like hieroglyphics which we do not understand. Etiology, on the other hand, teaches us that, according to the law of cause and effect, this particular condition of matter brings about that other particular condition, and thus it has explained it and performed its part. However, it really does nothing more than indicate the orderly arrangement according to which the states of matter appear in space and time, and teach in all cases what phenomenon must necessarily appear at a particular time in a particular place. It thus determines the position of phenomena in time and space, according to a law whose special content is derived from experience, but whose universal form and necessity is yet known to us independently of experience. But it affords us absolutely no information about the inner nature of any one of these phenomena: this is called a force of nature, and it lies outside the province of causal explanation, which calls the constant uniformity with which manifestations of such a force appear whenever their known conditions are present, a law of nature. But this law of nature, these conditions, and this appearance in a particular place at a particular time, are all that it knows or ever can know. The force itself which manifests itself, the inner nature of the phenomena which appear in accordance with these laws, remains always a secret to it, something entirely strange and unknown in the case of the simplest as well as of the most complex phenomena. For although as yet etiology has most completely achieved its aim in mechanics, and least completely in physiology, still the force on account of which a stone falls to the ground or one body repels another is, in its inner nature, not less strange and mysterious than that which produces the movements and the growth of an animal. The science of mechanics presupposes matter, weight, impenetrability, the possibility of communicating motion by impact, inertia and so forth as ultimate facts, calls them forces of nature, and their necessary and orderly appearance under certain conditions a law of nature. Only after this does its explanation begin, and it consists in indicating truly and with mathematical exactness, how, where and when each force manifests itself, and in referring every phenomenon which presents itself to the operation of one of these forces. Physics, chemistry, and physiology proceed in the same way in their province, only they presuppose