More precisely, the problem of Being arose as soon as Heidegger began to meditate with Brentano   the meaning of the word “being” (ὄν  ) for Aristotle  . Here he became fascinated by "is,” the little word that applies to everything - that enjoys an inconceivable polyvalence (makes world to be world and man to be man), without detriment to the marvelous unity of itself. Yet what of this unity? This must be Being itself, that which renders possible all “is.” Well, then, what about Being? What meaning does it have ? If it is true, as Aristotle says, that the function of metaphysics is to ask “what are beings as beings?” (τί τὸ ὄν ᾗ ὄν [ti to on   he on]), then, on the supposition that Being gives beings their “is,” should we not   first ask about Being itself? Such was the beginning of the way. Our only task is to watch its progression. [Note: In 1935, Heidegger meditates the sense of the Greek word for Being (εἶναι [einai]). After examining first its grammar (pp. 42-54), then its etymology (pp. 54-55), he finds the results meager enough, then resorts once more to meditating “is” (p. 68), concluding that the primal form of εἶναι must be neither the substantive nor infinitive, but the third person   singular, sc. “is” itself (p. 70). (Einführung in die Metaphysik   [GA40  , Tübingen: Niemeyer, 1953], pp. 40-70.] [RHPT:4]