These produce themselves in such a way that the ἀρχή resides in the producer as well as in the produced. ἐν αὑτοῖς γὰρ ἔχουσι ταῦτα τὴν ἀρχήν (a15f.), "for these have the ἀρχή in themselves. " In the case of τέχνη, on the contrary, the ἔργον resides precisely παρά, "beside," the activity; and precisely as ἔργον, as finished work, it is no longer the object of a ποίησις. That the shoes are finished means precisely that the cobbler has delivered them up. Now, insofar as the τέλος constitutes the ἀρχή, in the case of τέχνη the ἀρχή is in a certain sense not available. That shows that τέχνη is not a genuine ἀληθεύειν.
The object of τέχνη is the ποιητόν, the ἔργον, the finished product, which arises through a production and a fabrication. This ἔργον is a ἕνεκα τινος (1139b1), it is "for the sake of something," it has a relation to something else. It is οὐ τέλος ἀπλῶς (b2), "not an end pure and simple." The ἔργον contains in itself a reference to something else; as τέλος it refers away from itself: it is a πρός τι καί τινος (b2f. ), it is "for something and for someone." The shoe is made for wearing and is for someone. This double character entails that the ἔργον of the ποίησις is something produced for further use, for man. Τέχνη therefore possesses the ἔργον as an object of its ἀληθεύειν only as long as the ἔργον is not yet finished. As soon as the product is finished, it escapes the dominion of τέχνη : it becomes the object of the use proper to it. Aristotle expresses this precisely: the ἔργον is "παρά" (cf. Nic. Eth. I, 1, 1094a4f.). The ἔργον, as soon as it is finished, is παρά, "beside," τέχνη. Τέχνη, therefore, is concerned with beings only insofar as they are in the process of becoming. ἔστιν δὲ τέχνη πᾶσα περὶ γένεσιν (Nic. Eth. VI, 4, 1140a10f).
Aristotle distinguishes three possibilities regarding those beings which are determined by becoming: τῶν δὲ γιγνομένων τὰ μὲν φύσει γίγνεται τὰ δὲ τέχνῃ τὰ δὲ ἀπὸ ταὐτομάτου (Met. VII, 7, 1032a12ff.). "With regard to what becomes, the first is φύσει (by self-production) another is through τέχνη, another happens by chance." With regard to what happens by chance, Aristotle thinks above all of miscarriages and the like, i.e., that which is properly against nature, but which yet in a certain sense comes from itself, φύσει. The modes of becoming that are not those of nature Aristotle calls ποίησις. αἱ δ᾽ ἄλλαι γενέσεις λέγονται ποιήσεις (a26f.). Through such ποίησις, there comes to be ὅσων τὸ εἶδος ἐν τῇ ψυχῇ (b1), "everything whose outward look is in the soul. " We must consider this more closely in order to understand to what extent τέχνη in a certain sense has the ἀρχή and in a certain sense does not. For instance, in the case of the τέχνη ἰατρική, health is the εἶδος ἐν τῇ ψυχῇ, and in the case of οἰκοδομική it is the house. If a house is going to be built, then the course of the deliberation—of τέχνη—has basically the following structure: since the house is supposed to look such and such a way, it is necessary that such and such things be on hand.