Kant calls their transcendental character, and the process of explicating them is his famous _Transcendental Deduction_. [Sidenote: Kant's Principles Restricted to the Experiences which they Set in Order.] § 175. The restriction which Kant puts upon his method is quite essential to its meaning. I deduce the categories, for example, just in so far as I find them to be necessary to perception. Without them my perception is blind, I make nothing of it; with them my experience becomes systematic and rational. But categories which I so deduce must be forever limited to the rôle for which they are defined. Categories without perceptions are "empty"; they have validity solely with reference to the experience which they set in order. Indeed, I cannot even complete that order. The orderly arrangement of parts of experience suggests, and suggests irresistibly, a perfect system. I can even define the ideas and ideals through which such a perfect system might be realized. But I cannot in the Kantian sense attach reality to it because it is not indispensable to experience. It must remain an ideal which regulates my thinking of such parts of it as fall within the range of my perception; or it may through my moral nature become the realm of my living and an object of faith. In short, Kant's is essentially a "critical philosophy," a logical and analytical study of the special terms and relations of human knowledge. He denies the validity of these terms and relations beyond this realm. His critiques are an inventory of the conditions, principles, and prospects of that cognition which, although not alone ideally conceivable, is alone possible. [Sidenote: The Post-Kantian Metaphysics is a Generalization of the Cognitive and Moral Consciousness as Analyzed by Kant. The Absolute Spirit.]