By speaking of space as an Idea, I intend to imply... that the apprehension of objects as existing in space, and of the relations of position, &c., prevailing among them, is not a consequence of experience, but a result of a peculiar constitution and activity of the mind, which is independent of all experience in its origin, though constantly combined with experience in its exercise.
Part 1, Book 2, ch. 2, art. 1. - Philosophy of the Inductive Sciences (1840)