We may at this point consider Kant’s doctrine of “objective affinity.” It excellently enforces the main thesis which he is professing to establish, namely, that the conditions of _unitary_ consciousness are the conditions of _all_ consciousness. The language, however, in which the doctrine is expounded is extremely obscure and difficult; and before commenting upon Kant’s own methods of statement, it seems advisable to paraphrase the argument in a somewhat free manner, and also to defer consideration of the transcendental psychology which Kant has employed in its exposition.[898] Association can subsist only between ideas, both of which have occurred within the same conscious field. Now the fundamental characteristic of consciousness, the very condition of its existing at all, is its unity; and until this has been recognised, there can be no understanding of the associative connection which arises under the conditions which consciousness supplies. To attempt to explain the unity of consciousness through the mechanism of association is to explain an agency in terms of certain of its own effects. It is to explain the fundamental in terms of the derivative, the conditions in terms of what they have themselves made possible. Kant’s argument is therefore as follows. Ideas do not become associated merely by co-existing. They must occur together in a unitary consciousness; and among the conditions necessary to the possibility of association are therefore the conditions of the possibility of experience. Association is transcendentally grounded. So far from accounting for the unity of consciousness, it presupposes the latter as determining the conditions under which alone it can come into play. “...how, I ask, is association itself possible?... On my principles the thorough-going affinity of appearances is easily explicable. All possible appearances belong as representations to the totality of a possible self-consciousness. But as this self-consciousness is a transcendental representation, numerical identity is inseparable from it and is _a priori_ certain. For nothing can come to our knowledge save in terms of this original apperception. Now, since this identity must necessarily enter into the synthesis of all the manifold of appearances, so far as the synthesis is to yield empirical knowledge, the appearances are subject to _a priori_ conditions, with which the synthesis of their apprehension must be in complete accordance.... Thus all appearances stand in a thorough-going connection according to necessary laws, and therefore in a transcendental affinity of which the empirical is a mere consequence.”[899]