[Footnote 1:  This determination is important for psychology.  Since the inner sense shows nothing constant, but everything in a continual flux,—­for the permanent subject of our thoughts is an identical activity of the understanding, not an intuitable object,—­the concept of substance is not applicable to psychical phenomena.  Representations of a permanent (material substances) exist, indeed, but not permanent representations.  The abiding self (ego, soul) which we posit back of internal phenomena is, as the Dialectic will show, a mere Idea, which, or, rather, the object of which, maybe “thought” as substance, it is true, but cannot be “given” in intuition, hence cannot be “known.”]

As a result of the fact that the schematism permits a presentation of the categories in time intuition antecedent to all experience, the possibility is given of synthetic judgments a priori concerning objects of possible experience.  Such judgments, in so far as they are not based on higher and more general cognitions, are termed “principles,” and the system of them—­to be given, with the table of the categories as a guide, in the Analytic of Principles or the Doctrine of the Faculty of Judgment—­furnishes the outlines of “pure natural science.”  When thus the rules of the subsumption to be effected have been found in the pure concepts, and the conditions and criteria of the subsumption in the schemata, it remains to indicate the principles which the understanding, through the aid of the schemata, actually produces a priori from its concepts.

The principle of quantity is the Axiom of Intuition, the principle of quality the Anticipation of Perception; the principles of relation are termed Analogies of Experience, those of modality Postulates of Empirical Thought in General.  The first runs, “All intuitions are extensive quantities”; the second, “In all phenomena sensation, and the real which corresponds to it in the object, has an intensive quantity, i.e., a degree.”  The principle of the “Analogies” is, “All phenomena, as far as their existence is concerned, are subject a priori to rules, determining their mutual relation in time” (in the second edition this is stated as follows:  “Experience is possible only through the representation of a necessary connection of perceptions").  As there are three modes of time, there result three “Analogies,” the principles of permanence, of succession (production), and of coexistence.  These are:  (1) “In all changes of phenomena the substance is permanent, and its quantum is neither increased nor diminished in nature.” (2) “All changes take place according to the law of connection between cause and effect”; or, “Everything that happens (begins to be) presupposes something on which it follows according to a rule.” (3) “All substances, in so far as they are coexistent, stand in complete community, that is, reciprocity, one to another.”  And, finally, the three “Postulates”:  “That which agrees with the formal conditions of experience (in intuition and in concepts) is possible,” “That which is connected with the material conditions of experience (sensation) is actual” (perception is the only criterion of actuality).  “That which, in its connection with the actual, is determined by universal conditions of experience, is (exists as) necessary.”