we should have no guiding thread for the observation of a species of natural things which we have thought teleologically under the concept of natural purposes.

Now this concept brings the Reason into a quite different order of things from that of a mere mechanism of nature, which is no longer satisfying here. An Idea is to be the ground of the possibility of the natural product. But because this is an absolute unity of representation, instead of the material being a plurality of things that can supply by itself no definite unity of composition, — if that unity of the Idea is to serve at all as the a priori ground of determination of a natural law of the causality of such a form of composition, — the purpose of nature must be extended to everything included in its product. For if we once refer