main problem. His chief aim is to discover how it is that _a priori_ judgements are universally applicable. But, as Kant conceives the issue, the problem requires different treatment according as the judgements in question are related to the sensibility or to the understanding. Hence arises the distinction between the _Transcendental Aesthetic_ and the _Transcendental Analytic_, the former dealing with the _a priori_ judgements of mathematics, which relate to the sensibility, and the latter dealing with the _a priori_ principles of physics, which originate in the understanding. Again, within each of these two divisions we have to distinguish two problems, viz. 'What _a priori_ judgements are essentially related to the faculty in question?' and 'How is it that they are applicable to objects?' It is important, however, to notice that the distinction between the sensibility and the understanding, in the form in which it serves as a basis for distinguishing the _Aesthetic_ and the _Analytic_, is not identical with or even compatible with the distinction, as Kant states it when he is considering the distinction in itself and is not thinking of any theory which is to be based upon it. In the latter case the sensibility and the understanding are represented as inseparable faculties involved in _all_ knowledge.[13] Only from the union of both can knowledge arise. But, regarded as a basis for the distinction between the _Aesthetic_ and the _Analytic_, they are implied to be the source of different kinds of knowledge, viz. mathematics and the principles of physics. It is no answer to this to urge that Kant afterwards points out that space as an object presupposes a synthesis which does not belong to sense. No doubt this admission implies that even the apprehension of spatial relations involves the activity of the understanding. But the implication is really inconsistent with the existence of the _Aesthetic_ as a distinct part of the subject dealing with a special class of _a priori_ judgements. [13] B. 74-5, M. 45-6; cf. pp. 27-9. [14] B. 160 note, M. 98 note. CHAPTER III SPACE