of natural, moving, material beings. Only we uncover them, through the work of destructive reading. And having no experiential access, Aristotle ultimately tamed the dynamism of natural being by grounding it back in the ontology of οὐσία. Commenting on a passage from the Metaphysics in which Aristotle indicates that all categories of being (οὐσία of course, but also quantities, qualities, etc.) can be said to be either in the mode of potency or in the mode of actualization, Heidegger writes:
Insofar as δύναμις and ἐνέργεια determine οὐσία as such, which is the primary category and to which the others are related analogously, then δύναμις and ἐνέργεια also extend, as modifications, to all the remaining categories. In this way, everything is led back to οὐσία as the basic phenomenon, specifically such that ἐνέργεια is the highest kind of presence-at-hand [höchste Art des Vorhandenseins]. (BCAncP 151/180)
Heidegger seems to be saying that, had the relation between δύναμις and ἐνέργεια won the day and ultimately presented itself as fundamental, and had Aristotle then been able to allow these to determine his ontology, he might have ended up with something other than a metaphysics of presence. But this was not to be, for according to Heidegger here, the Greek experience of the world that led to Aristotle’s fateful positing of ουσίαι or “substances” as the fundamental constituents of the world also ultimately required that he subordinate δύναμις and ἐνέργεια to the concept of substance; that is, ultimately to the εἶδος or en-forming activity of concrete, present, completed beings in their presence-at- hand and utter availability for human knowing and mastery.