From this we are enabled to see what otherwise, though we could easily surmise it, could with difficulty be maintained with certainty and proved, viz. that the principle of a mechanical derivation of purposive natural products is consistent with the teleological, but in no way enables us to dispense with it. In a thing that we must judge as a natural purpose (an organised being) we can no doubt try all the known and yet to be discovered laws of mechanical production, and even hope to make good progress therewith; but we can never get rid of the call for a quite different ground of production for the possibility of such a product, viz. causality by means of purposes. Absolutely no human Reason (in fact no finite Reason like ours in quality, however much it may surpass it in degree) can hope to understand the production of even a blade of grass by mere mechanical causes. As regards the possibility of such an object, the teleological connexion of causes and effects is quite indispensable for the Judgement, even for studying it by the clue of experience. For external objects as phenomena an adequate ground related to purposes cannot be met with; this, although it lies in nature, must only be sought in the supersensible substrate of nature, from all possible insight into which we are cut off. Hence it is absolutely impossible for us to produce from nature itself grounds of explanation for purposive combinations; and it is necessary by the constitution of the human cognitive faculties to seek the supreme ground of these purposive combinations in an original Understanding as the cause of the world. § 78. _Of the union of the principle of the universal mechanism of matter with the teleological principle in the Technic of nature_