The science of all the principles of sensibility a priori, I call transcendental aesthetic.* There must, then, be such a science forming the first part of the transcendental doctrine of elements, in contradistinction to that part which contains the principles of pure thought, and which is called transcendental logic.
From the Wikipedia article on Critique of Pure Reason: Transcendental Aesthetic and the Transcendental Logic, (reflect) his basic distinction between sensibility and the understanding.
