The above appears to have no direct connection with the discussion of tuchê. What follows (after a dividing line in the notes) seems to have more of a connection in explaining how it is possible in Aristotle’s view to have a science of becoming. What becomes, arises, and perishes admits of determination and therefore of being an object of knowledge because it is a peras or “limit”; and what makes it a peras is having a beginning (ἀρχή) and an end (τέλος). Heidegger refers to Metaphysics Δ.17, presumably (though this is not specified in the notes) because Aristotle there lists “the for-the-sakeof- which” (τὸ οὗ ἕνεκα) as one of the meanings of peras (1022a8). The point Heidegger apparently wishes to make is that Aristotle in his account of becoming is guided by an understanding of being. “Because being is such, therefore is becoming something so and so constituted” (WP, 15). We are then given the example of a sperm enclosing the dunamis within itself: the point of the example is obscure, but we can guess it to be that the kind of power that the sperm has is defined by the kind of being it will become. Heidegger will continue to make precisely this point, but with technê this time as his example of becoming: “The τέχνη (itself a γένεσις) is such because the being, what it will produce and conserve, the εἶδος, is such” (WP, 15). That technê is here taken as the model for all being, including the natural growth of the embryo, is indicated by the obscure phrase that precedes the quoted sentence: “All being in the as-what-character of being-produced” (WP, 15). Furthermore, after claiming that “the εἶδος is the αἰτία of dealing so and so,” Heidegger adds, “As αἰτία in turn the ἀρχή of τέχνη and φύσις, of any γένεσις” (WP, 15). The talk of archê and aitia is motivated, Heidegger is suggesting, by the need to give becoming a limit, an end in being. This point is explicated in the notes that follow, which are therefore of great importance: “The ἀρχή is therefore ἀρχή because the εἶδος of beings is the αἰτία of dealing with them so-and-so in bringing them into being. That which is brought into being is the τέλος, the end. Every κίνησις has its τέλος. The τέλος is (as εἶδος) ἀρχή of the κίνησις and the αἰτία of its being constituted in such and such a way. The κίνησις that always has its τέλος in itself is the one that is most complete. Φύσις always has ἀρχή and τέλος in itself. Not τέχνη” (WP, 15). The telos is the archê that gives a movement its limit, its determinacy, indeed its being. This is why a movement that contains its telos within itself is more complete, more perfect, more fully realized than one that does not. Here, it is important to note, Heidegger recognizes that technê is not such a movement. Building or healing do not have their ends in themselves, but rather outside themselves, that is, in the house that is built or in the health