Aristotle's task, one he inherited from his predecessors, was to conceive
how being could be both a unity and a manifold, both simple and changing,
both always there and yet always becoming. Aristotle frames the question of force in Metaphysics ΘΙ primarily in terms of the problem of the one and the many, which rings so familiarly in our ears that we can miss the intensity of philosophical questioning involved here. A constant refrain in Aristotle's work is: to on legetai pollachos, being is said in many ways. But his, Heidegger says, is not just a formula. "Rather in this short sentence Aristotle formulates the wholly fundamental and new position that he worked out in philosophy in relation to all of his predecessors including Plato; not in the sense of a system but in the sense of a task." ...

Aristotle is not so much merely opposing Parmenides who insisted that being is simple and one, and excludes from itself all nonbeing. It is not that Parmenides insists that being is one, and Aristotle responds that it is many. Heidegger says that Aristotle does not deny and disavow the first decisive truth of philosophy as expressed by Parmenides. Rather, he first truly comprehends it by asking: if being is one, how can beings be? Must not multiplicity too belong to being as one? Must not nonbeing, the not-ness itself, belong to the essence of being? And how can this be done without destroying the fundamental Greek meaning of being, and without violating the Parmenidean prohibition against mixing being and nonbeing, thereby collapsing the difference between the two? These questions about Aristotle's place vis à vis the entire Greek philosophical tradition, and thus also the history of Western philosophy, are at the heart of Heidegger's 1931 lecture course. Heidegger says that what occurs in the Aristotelian confrontation with the question of being is a transformation of the sense of being and a shift in the understanding of the question of the oneness of being.

Heidegger, then, views Aristotle's philosophy as in some way a return to the presupposition of Parmenidean philosophy, the necessary horizon for Parmenidean thought that Parmenides himself may not have completely understood, though the aporia, the prohibition and impasse at the heart of his thinking, certainly echoes it, namely, the difference between being and beings. Aristotle is struggling to understand this difference in the proper way, that is, as an ontological difference and not merely as an attempt to account for the differences among beings or the different characteristics of any particular being.

P. 113-114

¶ 4:13 AM