Translated by Pete Ferreira
So, if through the interpretation of the four fundamental meanings Heidegger becomes convinced that they presuppose an idea of being as presence, and if then he examines the connection between this idea with those four fundamental meanings, here, in the examination of being as ἐνέργεια (where the manifestness of being reaches its highest expression), he is sent back to what is before ἐνέργειᾳ, before truth and all other meanings, he is sent back their common source. This source is being in its original happening, whose foundation is the structure of appearance (Ἀλήθεια) and having in itself the principle of movement (Φύσις).
In short, in retracing the spectrum of the four fundamental meanings, Heidegger finds in the Aristotelian determinations of truth and of ἐνέργεια a fundamental and illuminating indication: it not only allows him to think of the unity of being as presence within the horizon of an already made metaphysical decision, but also refers to that still unprejudiced and indecisive understanding of being that Heidegger believes he can grasp from the Presocratic experience of Φύσις.50
Next to this point, with the deepening of Heidegger's commitment in the overcoming and abandonment of metaphysics, the centrality of the confrontation with Aristotle (as well as the other major founding moments of Western thought) fades progressively and in its place a major investigation of the Presocratics takes over, particularly of Anaximander, Parmenides and Heraclitus. The 1939 essay about the essence and the concept of φύσις in Aristotle, Heidegger's last confrontation with the Aristotelian text, clearly stands in the context of his reading of the Presocratics.
50 This at least until the retraction Heidegger made, Zur Sache des Denkens, pp. 77-78 (trans. It., pp. 177-178). [On Time and Being, p. 52 ???]