conditions appear; while it itself, just because its existence is really only formal, i.e., is founded in the intellect must be thought as that which under all that change is absolutely permanent, thus with regard to time is without beginning and without end. This is why we cannot give up the thought that anything may be made out of anything, for example, gold out of lead; for this would only require that we should find out and bring about the intermediate states which matter, in itself indifferent, would have to pass through upon that path. For a priori we can never see why the same matter which is now the supporter of the quality lead could not some time become the supporter of the quality gold. Matter, as that which is only thought a priori, is distinguished from the a priori intuitions or perceptions proper by the fact that we can also think it entirely away; space and time, on the contrary, never. But this only shows that we can present to ourselves space and time in imagination without matter. For the matter which has once been placed in them, and accordingly thought as existing, we can never again absolutely think away, i.e., imagine it as vanished and annihilated, but are always forced to think of it merely as transferred to another space. So far, then, matter is as inseparably connected with our faculty of knowledge as space and time themselves. Yet even the difference that it must first be voluntarily thought as existing indicates that it does not belong so entirely and in every regard to the formal part of our knowledge as space and time, but also contains an element which is only given a posteriori. It is, in fact, the point of connection of the empirical part of our knowledge with the pure and a priori part, consequently the peculiar foundation-stone of the world of experience.
Only where all a priori assertions cease, therefore in the entirely empirical part of our knowledge of bodies, in their form, quality, and definite manner of acting, does that will reveal itself which we have already recognised and established as the true inner nature of
