This is only a maxim of the reflective, not of the determinant Judgement; consequently only subjectively valid for us, not objectively for the possibility of things themselves of this kind (in which both kinds of production may well cohere in one and the same ground). Further, without any concept,--besides the teleologically conceived method of production,--of a simultaneously presented mechanism of nature, no judgement can be passed on this kind of production as a natural product. Hence the above maxim leads to the necessity of an unification of both principles in judging of things as natural purposes in themselves, but does not lead us to substitute one for the other either altogether or in certain parts. For in the place of what is thought (at least by us) as possible only by design we cannot set mechanism, and in the place of what is cognised as mechanically necessary we cannot set contingency, which would need a purpose as its determining ground; but we can only subordinate the one (Mechanism) to the other (designed Technic), which may quite well be the case according to the transcendental principle of the purposiveness of nature. For where purposes are thought as grounds of the possibility of certain things, we must assume also means, whose law of working requires _for itself_ nothing presupposing a purpose,--a mechanical law--and yet can be a subordinate cause of designed effects. Thus--in the organic products of nature, and specially when prompted by their infinite number, we assume (at least as a permissible hypothesis) design in the combination of natural causes by particular laws as a _universal principle_ of the reflective Judgement for the whole of nature (the world),--we can think a great and indeed universal combination of mechanical with teleological laws in the productions of nature, without interchanging the principles by which they are judged or putting one in the place of the other. For, in a teleological judgement, the matter, even if the form that it assumes be judged possible only by design, can also, conformably to the mechanical laws of its nature, be subordinated as a means to the represented purpose. But, since the ground of this compatibility lies in that which is neither one nor the other (neither mechanism nor purposive combination), but is the supersensible substrate of nature of which we know nothing, the two ways of representing the possibility of such Objects are not to be blended together by our (human) Reason. However, we cannot judge of their possibility otherwise than by judging them as ultimately resting on a supreme Understanding by the connexion of final causes; and thus the teleological method of explanation is not eliminated.