the thing in self, and the one capacity of a thing in itself is impulsive force, for all other qualities can only be manifestations of this.
With naturalism, then, or the purely physical way of looking at things, we shall never attain our end; it is like a sum that never comes out. Causal series without beginning or end, fundamental forces which are inscrutable, endless space, beginningless time, infinite divisibility of matter, and all this further conditioned by a knowing brain, in which alone it exists just like a dream, and without which it vanishes – constitute the labyrinth in which naturalism leads us ceaselessly round. The height to which in our time the natural sciences have risen in this respect entirely throws into the shade all previous centuries, and is a summit which mankind reaches for the first time. But however great are the advances which physics (understood in the wide sense of the ancients) may make, not the smallest step towards metaphysics is thereby taken, just as a plane can never obtain cubical content by being indefinitely extended. For all such advances will only perfect our knowledge of the phenomenon; while metaphysics strives to pass beyond the phenomenal appearance itself, to that which so appears. And if indeed it had the assistance of an entire and complete experience, it would, as regards the main point, be in no way advantaged by it. Nay, even if one wandered through all the planets and fixed stars, one would thereby have made no step in metaphysics. It is rather the case that the greatest advances of physics will make the need of metaphysics ever more felt; for it is just the corrected, extended, and more thorough knowledge of nature which, on the one hand, always undermines and ultimately overthrows the metaphysical assumptions which till then have prevailed, but, on the other hand, presents the problem of metaphysics itself more distinctly, more correctly, and more fully, and separates it more clearly from all that is merely physical; moreover, the more perfectly and
