Categorical judgments have as their metalogical principle the laws of thought of identity and contradiction. But the _ground_ of the connection of the concept-spheres which gives _truth_ to the judgment, which is nothing but this connection, may be of very different kinds; and, according to this, the truth of the judgment is either logical, or empirical, or metaphysical, or metalogical, as is explained in the introductory essay, § 30-33, and does not require to be repeated here. But it is apparent from this how very various the direct cognitions may be, all of which exhibit themselves in the abstract, through the combination of the spheres of two concepts, as subject and predicate, and that we can by no means set up the sole function of the understanding as corresponding to them and producing them. For example, the judgments, “Water boils, the sine measures the angle, the will resolves, business distracts, distinction is difficult,” express through the same logical form the most different kinds of relations; but from this we obtain the right, however irregular the beginning may be, of placing ourselves at the standpoint of abstract knowledge to analyse direct intuitive knowledge. For the rest, the categorical judgment springs from knowledge of the understanding proper, in my sense, only when causation is expressed by it; this is, however, the case in all judgments which refer to a physical quality. For if I say, “This body is heavy, hard, fluid, green, sour, alkaline, organic, &c., &c.,” this always refers to its effect, and thus is knowledge which is only possible through the pure understanding. Now, after this, like much which is quite different from it (for example, the subordination of very abstract concepts), has been expressed in the abstract through subject and predicate, these mere relations of concepts have been transferred back to knowledge of perception, and it has been supposed that the subject and predicate of the judgment must have a peculiar and special correlative in perception, substance and accident. But I shall show clearly further on that the conception substance has no other true content than that of the conception matter. Accidents, however, are quite synonymous with kinds of effects, so that the supposed knowledge of substance and accident is never anything more than the knowledge of cause and effect by the understanding. But the special manner in which the idea of matter arises is explained partly in § 4 of the first book, and still more clearly in the essay on the principle of sufficient reason at the end of § 21, p. 77 (3d ed., p. 82), and in some respects we shall see it still more closely when we investigate the principle of the permanence of substance.