which is the same thing, if our understanding were intuitive instead of discursive; then the objects which we think would not need to be given us from another source (through sensuous intuition), but would be themselves produced in the act by which we thought them.  The divine spirit may be such an archetypal, creative understanding (intellectus archetypus), which generates objects by its thought; the human spirit is not such, and therefore is confined, with its knowledge, within the circle of possible perception.—­The conception of “intellectual intuition” leads to a distinction in regard to things in themselves:  in its negative meaning noumenon denotes a thing in so far as it is not the object of our sensuous intuition, in its positive meaning a thing which is the object of a non-sensuous intuition.  The positive thing in itself is a problematical concept; its possibility depends on the existence of an intuitive understanding, something about which we are ignorant.  The negative thing in itself cannot be known, indeed, but it can be thought; and the representation of it is a possible concept, one which is not self-contradictory[2] (a principle which is of great importance for practical philosophy).  Still further, it is an indispensable concept, which shows that the boundary where our intuition ends is not the boundary of the thinkable as well; and even if it affords no positive extension of knowledge[3] it is, nevertheless, very useful, since it sets bounds to the use of the understanding, and thus, as it were, negatively extends our knowledge.  That which lies beyond the boundary, the “how are they possible” (Wiemoeglichkeit) of things in themselves is shrouded in darkness, but the boundary itself, i.e., the “that they are possible” (Dassmoeglichkeit), of things in themselves, and the unknowableness of their nature, belongs to that which is within the boundary and lies in the light.  In this way Kant believed that the categories of causality and substance might be applied to the relation of things in themselves to phenomena without offending against the prohibition of their transcendent use, since here the boundary appeared only to be touched, and not overstepped.

[Footnote 1:  “A pure use of the categories is no doubt possible, that is, not self-contradictory, but it has no kind of objective validity, because it refers to no intuition to which it is meant to impart the unity of an object.  The categories remain forever mere functions of thought by which no object can be given to me, but by which I can only think whatever may be given to me in intuition” (Critique of Pure Reason, Max Mueller’s translation, vol. ii. p. 220).  Without the condition of sensuous intuition, for which they supply the synthesis, the categories have no relation to any definite object; for without this condition they contain nothing but the logical function, or the form of the concept, by means of which alone nothing can be known and distinguished as to any object belonging to it (Ibid., pp. 213, 214).]