This procedure distinguishes our philosophical method from that of all former systems. For they all start either from the object or from the subject, and therefore seek to explain the one from the other, and this according to the principle of sufficient reason. We, on the contrary, deny the validity of this principle with reference to the relation of subject and object, and confine it to the object. It may be thought that the philosophy of identity, which has appeared and become generally known in our own day, does not come under either of the alternatives we have named, for it does not start either from the subject or from the object, but from the absolute, known through “intellectual intuition,” which is neither object nor subject, but the identity of the two. I will not venture to speak of this revered identity, and this absolute, for I find myself entirely devoid of all “intellectual intuition.” But as I take my stand merely on those manifestoes of the “intellectual intuiter” which are open to all, even to profane persons like myself, I must yet observe that this philosophy is not to be excepted from the alternative errors mentioned above. For it does not escape these two opposite errors in spite of its identity of subject and object, which is not thinkable, but only “intellectually intuitable,” or to be experienced by a losing of oneself in it. On the contrary, it combines them both in itself; for it is divided into two parts, firstly, transcendental idealism, which is just Fichte’s doctrine of the ego, and therefore teaches that the object is produced by the subject, or evolved out of it in accordance with the principle of sufficient reason; secondly, the philosophy of nature, which teaches that the subject is produced little by little from the object, by means of a method called construction, about which I understand very little, yet enough to know that it is a process according to various forms of the principle of sufficient reason. The deep wisdom itself which that construction contains, I renounce; for as I entirely lack “intellectual intuition,” all those expositions which presuppose it must for me remain as a book sealed with seven seals. This is so truly the case that, strange to say, I have always been unable to find anything at all in this doctrine of profound wisdom but atrocious and wearisome bombast.
The systems starting from the object had always the whole world of perception and its constitution as their problem; yet the object which they take as their starting-point is not always this whole world of perception, nor its fundamental element, matter. On the contrary, a division of these systems may be made, based on the four classes of possible objects set forth in the introductory essay. Thus Thales and the Ionic school, Democritus, Epicurus, Giordano Bruno, and the French materialists, may be said to have started from the first class of objects, the real world: Spinoza (on account of his conception of substance, which is purely abstract, and exists only in his definition) and, earlier, the Eleatics, from the second class, the abstract conception: the Pythagoreans and Chinese philosophy in Y-King, from the third class, time, and consequently number: and, lastly, the schoolmen, who teach a creation out of nothing by the act of will of an extra-mundane personal being, started from the fourth class of objects, the act of will directed by knowledge.
Of all systems of philosophy which start from the object, the most consistent, and that which may be carried furthest, is simple materialism. It regards matter, and with it time and space, as existing absolutely, and ignores the relation to the subject in which alone all this really exists. It then lays hold of the law of causality as a guiding principle or clue, regarding it as a self-existent order (or arrangement) of things, veritas aeterna, and so fails to take account of the understanding, in which and for which alone causality is. It seeks the primary and most simple state of matter, and then tries to develop all the others from it; ascending from mere mechanism, to chemism, to polarity, to the vegetable and to the animal kingdom. And if we suppose this to have been done, the last link in the chain would be animal sensibility—that is knowledge—which would consequently now appear as a mere modification or state of matter produced by causality. Now if we had followed materialism thus far with clear ideas, when we reached its highest point we would suddenly be seized with a fit of the inextinguishable laughter of the Olympians. As if waking from a dream, we would all at once become aware that its final result—knowledge, which it reached so laboriously, was presupposed as the indispensable condition of its very starting-point, mere matter; and when we imagined that we thought matter, we really thought only the subject that perceives matter; the eye that sees it, the hand that feels it, the understanding that knows it. Thus the tremendous petitio principii reveals itself unexpectedly; for suddenly the last link is seen to be the starting-point, the chain a circle, and the materialist is like Baron Münchausen who, when swimming in water on horseback, drew the horse into the air with his legs, and himself also by his cue. The fundamental absurdity of materialism is that it starts from the objective, and takes as the ultimate ground of explanation something objective, whether it be matter in the abstract, simply as it is thought, or after it has taken form, is empirically given—that is to say, is substance, the chemical element with its primary relations. Some such thing it takes, as existing absolutely and in itself, in order that it may evolve organic nature and finally the knowing subject from it, and explain them adequately by means of it; whereas in truth all that is objective is already determined as such in manifold ways by the knowing subject through its forms of knowing, and presupposes them; and consequently it entirely disappears if we think the subject away. Thus materialism is the attempt to explain what is immediately given us by what is given us indirectly. All that is objective, extended, active—that is to say, all that is material—is regarded by materialism as affording so solid a basis for its explanation, that a reduction of everything to this can leave nothing to be desired (especially if in ultimate analysis this reduction should resolve itself into action and reaction). But we have shown that all this is given indirectly and in the highest degree determined, and is therefore merely a relatively present object, for it has passed through the machinery and manufactory of the brain, and has thus come under the forms of space, time and causality, by means of which it is first presented to us as extended in space and ever active in time. From such an indirectly given object, materialism seeks to explain what is immediately given, the idea (in which alone the object that materialism starts with exists), and finally even the will from which all those fundamental forces, that manifest themselves, under the guidance of causes, and therefore according to law, are in truth to be explained. To the assertion that thought is a modification of matter we may always, with equal right, oppose the contrary assertion that all matter is merely the modification of the knowing subject, as its idea. Yet the aim and ideal of all natural science is at bottom a consistent materialism. The recognition here of the obvious impossibility of such a system establishes another truth which will appear in the course of our exposition, the truth that all science properly so called, by which I understand systematic knowledge under the guidance of the principle of sufficient reason, can never reach its final goal, nor give a complete and adequate explanation: for it is not concerned with the inmost nature of the world, it cannot get beyond the idea; indeed, it really teaches nothing more than the relation of one idea to another.
Every science must start from two principal data. One of these is always the principle of sufficient reason in some form or another, as organon; the other is its special object as problem. Thus, for example, geometry has space as problem, and the ground of existence in space as organon. Arithmetic has time as problem, and the ground of existence in time as organon. Logic has the combination of concepts as such as problem, and the ground of knowledge as organon. History has the past acts of men treated as a whole as problem, and the law of human motives as organon. Natural science has matter as problem, and the law of causality as organon. Its end and aim is therefore, by the guidance of causality, to refer all possible states of matter to other states, and ultimately to one single state; and again to deduce these states from each other, and ultimately from one single state. Thus two states of matter stand over against each other in natural science as extremes: that state in