Translated by Pete Ferreira
But let us look more closely at the nature of the now, as the moment, that – as Aristotle says – is what is counted according to movement based on its before and after (ᾗ δ᾿αριθμητον το πρότερον καὶ ὕστερον, το νυν ἐστίν, 219 b 25). To understand the nature of the moment, you must be clear about the character of the before and the after; that is, you have to keep in mind that if their determination seems to be primarily a determination of local character, since each indicates the succession from one place to another, in fact it is a temporal determination, as the temporal sense of before and after must be assumed to understand the local sense; as Aristotle says, before and after have a ἀποστασις πρός τὸ νῦν (223a 5-6).
The instant, the now, then has the particular character of establishing the identity and otherness of time, i.e. both of setting up time and of dividing it into a now-no-longer and a now-not-yet, in a before and after (καὶ συνεχής τε δὴ ὁ χρόνος τῷ νῦν, καὶ διῄρηται κατὰ τὸ νῦν, 220a 5). This is because the instant in a certain way is always the same and in some other not (τὸ δὲ νῦν ἔστί μὲν ὡς τὸ αὐτό, ἔστί δ᾿ὡς οὐ τὸ αὐτό, 219b 12-13), since – as explained by Aristotle – it is τὸ γαρ νῦν τὸ αὐτὸ ὅ ποτ᾿ἦν — τὸ δ᾿εἶναι αὐτῷ ἕτερον (219b 10-11). Against the current interpretation, according to which it means that the instant is the same as far as existing and always different in its essence, Heidegger interprets this expression in the opposite direction, so that the instant would be the same in terms of essence and always other in terms of existence.