Heidegger is speaking of those multivocal and yet extreme concepts that we call "terms." Terms are sometimes shaped from the newly discovered matter by a new word. But they are also formed from a word already in common usage, so that a moment of meaning implicit in its current usage now becomes thematic in its terminological usage. This common currency of meaning operates in the averageness of "self-evident" understanding, of expressions which are the "common good" of the language into which each new human being grows and gets acclimated. In Aristotle's naming of being itself, accordingly, the coined term οὐσία is still accompanied (especially in his Ethics and Politics) by its everyday sense of property, house-and-hold, real estate. Even in ordinary usage, the reference is to an entity which is "there" in a distinctive way, namely, that entity which is there "to begin with and for the most part" in life. Thus, even common usage has words which refer both to the being and (implicitly) to the how of its being, property and its being had or owned ness, household goods in their everyday familiarity, real estate in its underlying "substantiality." "We likewise have, in our German expressions, particular meanings which refer not only to a being but also mean it in the how of its being: Hab und Gut, Vermogen, Anwesen" (8); translated seriatim into English: possessions as had and "good," wealth as capacity and power, real estate as present (anwesend). In short, in both common and scientific usage, "Being for the Greeks from the start means Da-sein, being-there. The further clarification of being in its being must move in the direction of the question, What does there mean?" (8). The whole course is therefore designed to view οὐσία, Da-sein, the How of being, through the bifocals of Greek and German.
Logic tells us that a concept receives its determination by means of a definition. A real definition thus determines what a res is in itself. For Kant, a concept, in contrast with an intuition, comes into its own in a definition, where it is understood in its inner possibility and becomes universally valid. But for Aristotle, ὁρισμός (definition, but ultimately "horizon," already a favorite word of Heidegger's in the previous semester) is not yet so sharply contoured and logically complete: it is rather a λόγος which determines an entity in its being as limited and measured by its πέρας, its "perimeter." Being means being finished. Aristotle can therefore take us back to the origin of the process of decay of this term of terms, in the course of which "definition" becomes a mere technique of thinking, and thus strays from being a "ground" possibility of human speech.
In definition, the concept becomes explicit. And yet, it is not thereby clear what the concept itself actually is in its conceptuality. [In order to come to this, we must turn from its logical completeness to its phenomenological origins, at the interface of the concept and its matter, ground,