The true idealism, on the contrary, is not the empirical but the transcendental. This leaves the empirical reality of the world untouched, but holds fast to the fact that every _object_, thus the empirically real in general, is conditioned in a twofold manner by the subject; in the first place _materially_ or as _object_ generally, because an objective existence is only conceivable as opposed to a subject, and as its idea; in the second place _formally_, because the mode of existence of an object, _i.e._, its being perceived (space, time, causality), proceeds from the subject, is pre-arranged in the subject. Therefore with the simple or Berkeleian idealism, which concerns the object in general, there stands in immediate connection the Kantian idealism, which concerns the specially given _mode or manner_ of objective existence. This proves that the whole material world, with its bodies, which are extended in space and, by means of time, have causal relations to each other, and everything that depends upon this—that all this is not something which is there _independently_ of our head, but essentially presupposes the functions of our brain _by means of which_ and _in_ which alone _such_ an objective arrangement of things is possible. For time, space, and causality, upon which all those real and objective events rest, are themselves nothing more than functions of the brain; so that thus the unchangeable _order_ of things which affords the criterion and clue to their empirical reality itself proceeds only from the brain, and has its credentials from this alone. All this Kant has expounded fully and thoroughly; only he does not speak of the brain, but calls it “the faculty of knowledge.” Indeed he has attempted to prove that when that objective order in time, space, causality, matter, &c., upon which all the events of the real world ultimately rest, is properly considered, it cannot even be conceived as a self-existing order, _i.e._, an order of the thing in itself, or as something absolutely objective and unconditionally given, for if one tries to think this out it leads to contradictions. To accomplish this was the object of the antinomies, but in the appendix to my work I have proved the failure of the attempt. On the other hand, the Kantian doctrine, even without the antinomies, leads to the insight that things and the whole mode of their existence are inseparably bound up with our consciousness of them. Therefore whoever has distinctly grasped this soon attains to the conviction that the assumption that things also exist as such, apart from and independently of our consciousness, is really absurd. That we are so deeply involved in time, space, causality, and the whole regular process of experience which rests upon them, that we (and indeed the brutes) are so perfectly at home, and know how to find our way from the first—this would not be possible if our intellect were one thing and things another, but can only be explained