consists simply in framing ideas by means of subjective forms, affords us always mere phenomena, not the true being of things. This is the explanation of the fact that in all that we know there remains hidden from us a certain something, as quite inscrutable, and we are obliged to confess that we cannot thoroughly understand even the commonest and simplest phenomena. For it is not merely the highest productions of nature, living creatures, or the complicated phenomena of the unorganised world that remain inscrutable to us, but even every rock-crystal, every iron-pyrite, by reason of its crystallographical, optical, chemical, and electrical properties, is to the searching consideration and investigation an abyss of incomprehensibilities and mysteries. This could not be the case if we knew things as they are in themselves; for then at least the simpler phenomena, the path to whose qualities was not barred for us by ignorance, would necessarily be thoroughly comprehensible to us, and their whole being and nature would be able to pass over into our knowledge. Thus it lies not in the defectiveness of our acquaintance with things, but in the nature of knowledge itself. For if our perception, and consequently the whole empirical comprehension of the things that present themselves to us, is already essentially and in the main determined by our faculty of knowledge, and conditioned by its forms and functions, it cannot but be that things exhibit themselves in a manner which is quite different from their own inner nature, and therefore appear as in a mask, which allows us merely to assume what is concealed beneath it, but never to know it; hence, then, it gleams through as an inscrutable mystery, and never can the nature of anything entire and without reserve pass over into knowledge; but much less can any real thing be construed a priori, like a mathematical problem. Thus the empirical inscrutableness of all natural things is a proof a posteriori of the ideality and merely phenomenal-actuality of their empirical existence.
According to all this, upon the path of objective know-
