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Chapter 2

is a real thing?” comes down to what one means by realness, or, in Greek, what one means by οὐσία, the very “is-ness” of “what-is,” or the “being” of “what-has-being.” Heidegger rejects the usual translation of οὐσία as “substance,” from the Latin substantia (even though he might have appreciated its etymology: the rare verb substo, the basis of

substantia
, has the sense of “to be present”). Medieval translations of οὐσία as essentia (the “esse-ness” of what-has-esse) tend to understand that Latin term as “essence” in contradistinction to “existence,” whereas in Aristotle οὐσία covers both essence and existence. Therefore, to express the οὐσία of τὸ ὄν (the realness of the real) while avoiding those translation traps, Heidegger translates οὐσία as the “beingness of things” (“die Seiendheit des Seienden,” which is exactly the same as das Sein des Seienden in its traditional sense).11 But again, this usage still leaves open the question of what Heidegger thinks Sein/Seiendheit/realness cashes out as in Aristotle and in his own work.

Οὐσία was a common Greek term before Plato and Aristotle brought it into the province of philosophy. In its primary sense it refers to a thing or things. But the philosophers used it to refer also to the realness of a thing; and one has to be clear on which of the two usages is operative in a given case—that is, whether in a text from Plato or Aristotle οὐσία means a particular thing or the very realness of that thing. When Heidegger refers to οὐσία, he means it predominantly in the second sense: as the Sein or realness of a thing.

In classical Greek, regardless of whether οὐσία is used non-philosophically to refer to the real, or philosophically to refer to the realness of the real, the notion of “real” has two connotations: a thing’s presence and its stability: being as the stable presence of something. Here “presence” means availability, with overtones of what belongs to a person. In its pre-philosophical sense, οὐσία meant what is one’s own: property in the form of goods or wealth, livestock, land, or even a worker’s tools. Oὐσία refers to one’s stable possessions or holdings, something that one has a stake in, as with John Locke’s “to have a property in something.”12 Heidegger’s argument is worth citing at length.


In Greek οὐσία means things—not just any things but things that in a certain way are exemplary in their realness, namely the things that belong to you, your goods and possessions, house and home (what you own, your wealth), what


11. See GA 15: 344.13–15 = 46.35–36: “Frage nach dem Sein des Seienden, mit anderen Worten: Frage nach der Seiendheit des Seienden.” GA 66: 200.32 = 176.35: “die Seiendheit als das Sein.” GA 74: 6.3: “Seiendheit ist das Sein.” GA 66: 316.25–27 = 281.31–33: “Unverborgenheit des Seienden und Offenbarkeit des Seienden besagt griechisch: Anwesung und d.h. Sein und d.h. Seiendheit und d.h. Seiendes als solches.” Aquinas calls this Seiendheit “entitas” in his commentary on Aristotle’s Metaphysics, Book VII, lectio 2, no. 35 (1304).
12. John Locke, Two Treatises, chapter V § 25, 111.