At first glance, the recent translation of the summer semester 1926
lecture course Basic Concepts of Ancient Philosophy
seems pretty exciting. A class on Greek ontology from Thales to Aristotle, given while Heidegger was finishing up Being and Time
. However, because he was busy with that book's manuscript, he had less time to devote to the course. So, whereas most of Heidegger's lecture courses were written out in complete sentences beforehand, in this case Heidegger limited himself to 77 pages of notes. Since those were double-sided, and supplemented by slips of paper, that still works out to 158 pages in the translation, with an additional 64 pages of student transcripts. This volume could be the basis for a book on Heidegger's interpolation of his way of thinking with the Greeks. Many of the sections of this course are covered in depth in other courses; e.g. Heraclitus, Parmenides, Plato's cave allegory and Theatetus
, sections of Aristotle's Metaphysics
Here's a bit on Plato's αγαθόν.
οὐσία and αγαθόν. How do we proceed form the principles and basic determinations of beings, from the Ideas as structures of Being, to the Idea of the αγαθόν, from the logical to the ethical, from Being to the "ought"? οὐσία and αγαθόν.
Being, i.e., the Being of beings [das Seinde-Sein], is that which is understood purely and simply for the sake of itself and is the only thing that can be understood in such a way. For the sake of itself: the end of all understanding. If I say "for the sake of itself," that is still an assertion about it: end, πέρας, αγαθόν. In a naively ontic sense: something higher than Being itself, which, moreover, still is Being itself. Considered more closely, however, not an assertion about Being, but one that turns away from Being and is precisely not directed to Being itself but, instead, approaches it obliquely, in relation to how it is understood, what it is for the understanding and not as it is itself. Even "Being" as principle is a derivative characterization.
At issue here is the Being of Dasein, the soul itself. At issue is Being, the "for the sake of which" of this being, that which it has "to be." The being of whose Being an understanding of Being pertains. Understanding of Being: the potentiality-for-being wherein Being is at issue. In the Greek sense: that which is at issue, the for the sake of which, itself as a being, the good. Being is πέρας, "end," the αγαθόν. It is a matter of the αγαθόν, because Being is understood as a being, an existing property, the good. More is said about the soul than the good, according to its sense, can bear. To restrict the ontological assertion to its proper limits.
To know, to see, is an an action, being out for.
αγαθόν, πέρας, any seeing is already, and above all, related to the light. The understanding of Being is brought to completion in seeing. Being through the ἰδέα, "something see"; Being through the αγαθόν, the "for the sake of which," the "end." The Idea of the good is Being in the proper sense and is a being in the proper sense.