of being and nonbeing because only in this way could the truth of being appear in its difference. Heidegger says: “only when we turn thoughtfully toward what has already been thought (but presupposed and then forgotten) will we be turned to use for what must still be thought.”30 It is with this question that Heidegger begins Sein und Zeit.31
Before continuing with his interpretation of Aristotle’s Physics B 1, Heidegger summarizes what Aristotle has so far accomplished and outlines the importance of his confrontation with Antiphon. We have determined through ἐπαγωγή that natural beings are in movement. Not in the sense that they are at any given moment necessarily in motion (as regards to locomotion or alteration, etc.) but in the sense that being-moved is their way of being. It is this way of being that directs and makes possible the kinds of motion that beings undergo. This way of being is φύσις. Φύσις is the ἀρχή of beings that move according to their nature. Φύσις is not motion but the ἀρχή of the motion in beings such that it lets them be the beings they are. The ἀρχή both directs and governs the emerging forth and lets that which directs and governs the upsurgence emerge into unconcealment. It is both Ausgang and Verfügung thought in their togetherness. The τέλος, that toward which a being reaches and in which it fulfills itself, directs the coming-to-be of a being. That “from which” and “out of which” a being emerges is the origin. But both the origin and the τέλος are essentially the same. Φύσις is both. It is ausgängliche Verfügung. The ἀρχή holds a being in its togetherness and lets it come forth as a whole. The diverse moments and phases of the coming to be of a natural being do not contradict the meaning of being as οὐσία. Rather being-moved is the way in which natural beings fulfill their οὐσία. Therefore only by understanding κίνησις in the proper way can we understand the “nature” of φύσις as the ἀρχή of the being-moved of natural beings.
Heidegger points to the beginning of Chapter III of Book II of the Physics in support of this seemingly circular reasoning. There Aristotle says:
Since φύσις is the originating and governing over being-moved and thus over the upsurgence which bursts into the open, our methodos must not allow that κίνησις essentially is to remain in concealment. For whenever κίνησις remains unfamiliar, φύσις also remains in unfamiliarity.” (Physics 200 b12–15; WBP 341)
Aristotle’s “method” requires both a comportment toward κίνησις and toward φύσις. Unless we see what κίνησις is, that is, how κίνησις is in its