Productive imagination acts in the manner required to yield experiences which are capable of relation to the unity of self-consciousness, _i.e._ of being found to conform to the unity of the categories. Why it should act in this manner cannot be explained; but it is none the less, on Critical principles, a legitimate assumption, since only in so far as it does so can experience, which _de facto_ exists, be possible in any form. As a condition _sine qua non_ of actual and possible experience, the existence of such a faculty is, Kant argues, a legitimate inference from the results of the transcendental deduction. Though Kant’s insistence upon the conscious character of understanding compels him to distinguish between it and the imagination, he has also to recognise their kinship. If imagination can never act save in conformity with the _a priori_ forms of understanding, some reason must exist for their harmony. This twofold necessity of at once distinguishing and connecting them is the cause of the hesitating and extremely variable account which in both editions of the _Critique_ is given of their relation. In several passages the understanding is spoken of as simply imagination which has attained to consciousness of its activities.[920] Elsewhere he explicitly states that they are distinct and separate. From this second point of view Kant regards imagination as mediating between sense and understanding, and, though reducible to neither, akin to both. Only on one point is Kant clear and definite, namely, that it is to productive imagination that the _generation_ of unified experience is primarily due. In it something of the fruitful and inexhaustible character of noumenal reality is traceable. Doubtless one chief reason for his choice of the title imagination is the creative character which in popular thought has always been regarded as its essential feature. As Kant, speaking of schematism, which is a process executed by the imagination, states in A 141: “This schematism ... is an _art_ (_Kunst_) concealed in the depths of the human soul.”[921] This description may perhaps be interpreted in the light of Kant’s account of the creative character of artistic genius in the _Critique of Judgment_, for there also imagination figures as the truly originative or creative faculty of the human spirit. To its noumenal character we may also trace its capacity of combining those factors of sense and understanding which in the realm of appearance remain persistently opposed.[922] Imagination differs from the understanding chiefly in that it is at once more comprehensive and also more truly creative. It supplements the functional forms with a sensuous content, and applies them dynamically in the generation of experience. The schemata, which the productive imagination is supposed to construct, are those generalised forms of temporal and spatial existence in which alone the unity of experience necessary to apperception can be realised. They are