to know them, not by external intuition but by self-perception and self-consciousness. That which has not the properties of the material can not be the form of activity of something which is material. Activity of consciousness and cerebral function always come to be known through different sources of experience. The encroachment of materialism consists in the fact that it effaces this essential distinction.
Materialism has never observed that, even if all its assertions are admitted to be just, it yet overlooks something which gives rise to a new and for it a terrible problem—namely, the circumstance that movement in space is known to us only as an object of our consciousness. For the theory of knowledge such notions as consciousness, idea, and intuition lie deeper than such notions as matter and movement. For this reason an absolute and decided materialism was possible only in ancient times, before the awakening of more deeply penetrating philosophical reflection. Democritus is the only consistent materialist. None of the modern materialistic writers can speak with the calm and the certainty with which Lucretius in his majestic verses sets forth the doctrine of Democritus. Modern materialists for the most part confess that, even if we can reduce everything to matter, yet we can not know what matter is in itself. Thus La Mettrie, Holbach, Cabanis, not to speak of the wild and rambling inconsistencies of the most recent writers (Büchner, Moleschott).
But the objection here urged against materialism is not its desire that conscious life shall accept as the only reality something which is given only as an object of consciousness, and can be represented only through the activity of consciousness; but rather that the facts impel us to the result that materialism offends against the conceptions derived from experience itself.
In treating of monistic spiritualism as the third possible hypothesis, we must always hold fast the distinction between an empirical and metaphysical way of looking at things. Very many confusions relative to the problem before us are the result of overlooking this distinction. Monistic spiritualism is the view according to which the mind is a mental (geistige) substance, and the mental is the only reality; everything material, all movement in space, is but an outer form of a mental life. It is based on the impossibility of explaining the mental by the material, and on the fact, partly overlooked, partly undervalued, by materialism, that our conception of matter is a mental product, and that apart from our conception of it we do not know what matter is. Thus the mental is a presupposition on which all thought rests; and a reasonable hypothesis is formed only by the reduction of the less known to the better known. The mental is properly the only thing fully intelligible to us, for in it we have not only a knowledge of outward circumstances and relations, but a knowledge also of the thing itself. . . .
