Reason is a faculty of principles and proceeds in its extremest advance to the unconditioned; on the other hand, the Understanding stands at its service always only under a certain condition which must be given. But without concepts of Understanding, to which objective reality must be given, the Reason cannot form any objective (synthetical) judgement; and contains in itself, as theoretical Reason, absolutely no constitutive but merely regulative principles. We soon see that where the Understanding cannot follow, the Reason is transcendent, and shows itself in Ideas formerly established (as regulative principles), but not in objectively valid concepts. But the Understanding which cannot keep pace with Reason but yet is requisite for the validity of Objects, limits the validity of these Ideas to the subject, although [extending it] generally to all [subjects] of this kind. That is, the Understanding limits their validity to the condition, that according to the nature of our (human) cognitive faculties, or, generally, according to the concept which we _ourselves_ can _make_ of the faculty of a finite intelligent being, nothing else can or must be thought; though this is not to assert that the ground of such a judgement lies in the Object. We shall adduce some examples which, though they are too important and difficult to impose them on the reader as proved propositions, yet will give him material for thought and may serve to elucidate what we are here specially concerned with.