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We say of nature and its faculty in organised products far too little if we describe it as an analogon of art; for this suggests an artificer (a rational being)279 external to it. Much rather does it organise itself and its organised products in every species, no doubt after one general pattern but yet with suitable deviations, which self-preservation demands according to circumstances. We perhaps approach nearer to this inscrutable property, if we describe it as an analogon of life; but then we must either endow matter, as mere matter, with a property which contradicts its very being (hylozoism), or associate therewith an alien principle standing in communion with it (a soul). But in the latter case we must, if such a product is to be a natural product, either presuppose organised matter as the instrument of that soul, which does not make the soul a whit more comprehensible; or regard the soul as artificer of this structure and so remove the product from (corporeal) nature. To speak strictly, then, the organisation of nature has in it nothing analogous to any causality we know.108 Beauty in nature can be rightly described as an analogon of art, because it is ascribed to objects only in reference to reflection upon their external aspect, and consequently only on account of the form of their external surface. But internal natural perfection, as it belongs to those things which are only possible as natural purposes, and are therefore called organised beings, is not analogous to any physical, i.e. natural, faculty known to us; nay even,280 regarding ourselves as, in the widest sense, belonging to nature, it is not even thinkable or explicable by means of any exactly fitting analogy to human art.
The concept of a thing as in itself a natural purpose is therefore no constitutive concept of Understanding or of Reason, but it can serve as a regulative concept for the reflective Judgement, to guide our investigation about objects of this kind by a distant analogy with our own causality according to purposes generally, and in our meditations upon their ultimate ground. This latter use, however, is not in reference to the knowledge of nature or of its original ground, but rather to our own practical faculty of Reason, in analogy with which we considered the cause of that purposiveness.
Organised beings are then the only beings in nature which, considered in themselves and apart from any relation to other things, can be thought as possible only as purposes of nature. Hence they first afford objective reality to the concept of a purpose of nature, as distinguished from a practical purpose; and so they give to the science of nature the basis for a teleology, i.e. a mode of judgement about natural Objects according to a special principle which otherwise we should in no way be justified in introducing (because we cannot see a priori the possibility of this kind of causality).
This principle, which is at the same time a definition, is as follows: An organised product of nature is one in which every part is reciprocally purpose, [end] and means. In it nothing is vain, without281 purpose, or to be ascribed to a blind mechanism of nature.
This principle, as regards its occasion, is doubtless derived from experience, viz. from that methodised experience called observation; but on account of the universality and necessity which it ascribes to such purposiveness it cannot rest solely on empirical grounds, but must have at its basis an a priori principle, although it be merely regulative and these purposes lie only in the idea of the judging [subject] and not in an effective cause. We may therefore describe the aforesaid principle as a maxim for judging of the internal purposiveness of organised beings.
It is an acknowledged fact that the dissectors of plants and animals, in order to investigate their structure and to find out the reasons, why and for what end such parts, such a disposition and combination of parts, and just such an internal form have been given them, assume as indisputably necessary the maxim that nothing in such a creature is vain; just as they lay down as the fundamental proposition of the universal science of nature, that nothing happens by chance. In fact, they can as little free themselves from this teleological proposition as from the universal physical proposition; for as without the latter we should have no experience at all, so without the former 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 possibility282 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 action of this sort on the whole to any supersensible ground of determination beyond the blind mechanism of nature, we must judge of it altogether according to this principle; and we have then no reason to regard the form of such a thing as partly dependent on mechanism—for by such mixing up of disparate principles no certain rule of judging would be left.
For example, it may be that in an animal body many parts can be conceived as concretions according to mere mechanical laws (as the hide, the bones, the hair). And yet the cause which brings together the required matter, modifies it, forms it, and puts it in its appropriate place, must always be judged of teleologically; so that here everything must be considered as organised, and everything again in a certain relation to the thing itself is an organ.
We have already said above that the external purposiveness of natural things affords no sufficient warrant for using them as purposes of nature in order to explain their presence, and for regarding their contingently purposive effects as the grounds of their presence according to the principle of final283 causes. Thus we cannot take for natural purposes, rivers because they promote intercourse among inland peoples, mountains because they contain the sources of the rivers and for their maintenance in rainless seasons have a store of snow, or the slope of the land which carries away the water and leaves the country dry; because although this shape of the earth's surface be very necessary for the origin and maintenance of the vegetable and animal kingdoms, it has nothing in itself for the possibility of which we are forced to assume a causality according to purposes. The same is true of plants which man uses for his needs or his pleasures; of beasts, the camel, the ox, the horse, dog, etc., which are indispensable to him as well for food as because they are used in his service in many different ways. In the case of things which we have no reason for regarding in themselves as purposes, such external relation can only be hypothetically judged as purposive.
