Now this table may be regarded at pleasure either as a collection of the eternal laws of the world, and therefore as the basis of our ontology, or as a chapter of the physiology of the brain, according as one assumes the realistic or the idealistic point of view; but the second is in the last instance right. On this point, indeed, we have already come to an understanding in the first chapter; yet I wish further to illustrate it specially by an example. Aristotle’s book “_De Xenophane_,” &c., commences with these weighty words of Xenophanes: “Αϊδιον ειναι φησιν, ει τι εστιν, ειπερ μη ενδεχεται γενεσθαι μηδεν εκ μηδενος.” (_Æternum esse, inquit, quicquid est, siquidem fieri non potest, ut ex nihilo quippiam existat._) Here, then, Xenophanes judges as to the origin of things, as regards its possibility, and of this origin he can have had no experience, even by analogy; nor indeed does he appeal to experience, but judges apodictically, and therefore _a priori_. How can he do this if as a stranger he looks from without into a world that exists purely objectively, that is, independently of his knowledge? How can he, an ephemeral being hurrying past, to whom only a hasty glance into such a world is permitted, judge apodictically, _a priori_ and without experience concerning that world, the possibility of its existence and origin? The solution of this riddle is that the man has only to do with his own ideas, which as such are the work of his brain, and the constitution of which is merely the manner or mode in which alone the function of his brain can be fulfilled, _i.e._, the form of his perception. He thus judges only as to the _phenomena of his own brain_, and declares what enters into its forms, time, space, and causality, and what does not. In this he is perfectly at home and speaks apodictically. In a like sense, then, the following table of the _Prædicabilia a priori_ of time, space, and matter is to be taken:— Prædicabilia _A Priori_.