Kant’s discussion of the concept of causality in A 90 may seem to conflict with the above contention--that it is its applicability to things in themselves which Kant is considering. But this difficulty vanishes if we bear in mind that here, as in the _Dissertation_, there is no such distinction as we find in Kant’s later more genuinely phenomenalist position, between the objects causing our sensations and _things in themselves_.[3] The purely intelligible object, supposed to remain after elimination of the empirical and _a priori_ sensory factors, is the thing in itself. The objects apprehended through sense are real, only not in their sensuous form. There are two connected facts which together may perhaps be taken as evidence that I. § 13 is later than II. 3 _b_. Intellectual concepts are reinstated alongside the _a priori_ concepts of space and time. Kant has evidently in the meantime given up the attempt to construe the former as empirical in origin. That that attempt was earlier in time would seem to be proved by the further fact, that the _a priori_ concepts are here viewed as performing the same kind of function as that ascribed in II. 3 _b_ to concepts that are empirical. They are conditions of the “synthetic unity of thought.”[811] This view of the function of concepts is certainly fundamental and important, and Kant permanently retained it from his previous abortive method of ‘deduction.’ But it was a long step from the discovery of the distinction between empirical and _a priori_ concepts to its fruitful application. That involved appreciation of the further fact that the two problems, separately stated in the letter to Herz and separately dealt with in II. 3 _b_ and in I. § 13--the problem of the relation of _sense_-representations, and the problem of the relation of _intellectual_ representations, to an object,--are indeed one and the same, soluble from one and the same standpoint, by one and the same method of deduction, namely, by reference to the possibility of experience. Only in and through relation to an object can sense-representations be apprehended; and only as conditions of such sense-experience are the categories objectively valid. Relation to an object is constituted by the categories, and is necessary in reference to sense-representations, because only thereby is consciousness of any kind possible at all.