Every being, in turn, has possibility in it, in a different way in each case. Possibility belongs to the chalk. It itself has in itself a definite appropriateness for a definite use. Of course, when we look for possibility in the chalk, we are accustomed and inclined to say that we do not see it and do not grasp it. But that is a prejudice. The elimination of this prejudice is part of the unfolding of our question. For now, this question should just open up beings, in their wavering between not-Being and Being. Insofar as beings stand up against the extreme possibility of not-Being, they themselves stand in Being, and yet they have never thereby overtaken and overcome the possibility of not-Being.
Suddenly we are speaking here about the not-Being and Being of beings, without saying how what we call Being is related to beings themselves. Are they the same? The being and its Being? The distinction! What, for example, is the being <das Seiende> in this piece of chalk? Already this question is ambiguous, because the word “being” can be understood in two ways, as can the Greek τὸ ὄν. On the one hand, being means what at any time is in being, in particular this grayish-white, light, breakable mass, formed in such and such a way. On the other hand, “being” means that which, as it were, “makes” this be a being instead of nonbeing <nichtseiend>, that which makes up the Being in the being, if it is a being. In accordance with this twofold meaning of the word “being,” the Greek τὸ ὄν often designates the second meaning, that is, not the being itself, what is in being, but rather [24|34] “the in-being,” beingness, to be in being, Being.23 In contrast, the first meaning of “being” names the things themselves that are in being, either individually or as a whole, but always with reference to these things and not to their beingness, οὐσία.24
23. “… also nicht das Seiende selbst, was seiend ist, sondern ‘das Seiend,’ die Seiendheit, das Seiendsein, das Sein.”
24. The Greek noun οὐσία is formed from the present participle of the verb εἶναι (to be). Normally meaning “goods, possessions,” it is developed by Plato and Aristotle into a central philosophical concept, and is usually translated as “essence” or “substance.” Heidegger’s Seiendheit (beingness) corresponds directly to the grammatical structure of οὐσία.