To entities such as these, their Being is 'a matter of indifference';1 or more precisely, they 'are' such that their Being can be neither a matter of indifference to them, nor the opposite. Because Dasein has in each case mineness [Jemeinigkeit], one must always use a personal pronoun when one addresses it: 'I am', 'you are'.
Furthermore, in each case Dasein is mine to be in one way or another. Dasein has always made some sort of decision as to the way in which it is in each case mine [je meines]. That entity which in its Being has this very Being as an issue, comports itself towards its Being as its ownmost possibility. In each case Dasein is its possibility, and it 'has' this possibility, but not just as a property [eigenschaftlich], as something present-at-hand would. And because Dasein is in each case essentially its own possibility, it can, in its very Being, 'choose' itself and win itself; it can also lose itself and never win itself; or only 'seem' to do so. But only in so far as it is  essentially something which can be authentic—that is, something of its own2—can it have lost itself and not yet won itself. As modes of Being, authenticity and inauthenticity (these expressions have been chosen terminologically in a strict sense) are both grounded in the fact that any Dasein whatsoever is characterized by mineness.3 But the inauthenticity of Dasein does not signify any 'less' Being or any 'lower' degree of Being. Rather it is the case that even in its fullest concretion Dasein can be characterized by inauthenticity —when busy, when excited, when interested, when ready for enjoyment.
The two characteristics of Dasein which we have sketched—the priority of 'existentia' over essentia, and the fact that Dasein is in each case mine [die Jemeinigkeit]—have already indicated that in the analytic of this entity we are facing a peculiar phenomenal domain. Dasein does not have the kind of Being which belongs to something merely present-at-hand within the world, nor does it ever have it. So neither is it to be presented thematically as something we come across in the same way as we come across what is present-at-hand.
1 'gleichgültig'. This adjective must be distinguished from the German adjective 'indifferent', though they might both ordinarily be translated by the English 'indifferent', which we shall reserve exclusively for the former. In most passages, the latter is best translated by 'undifferentiated' or 'without further differentiation'; occasionally, however, it seems preferable to tram.late it by 'Indifferent' with an initial capital. We shall follow similar conventions with the nouns 'Gleichgültigkeit' and 'Indifferenz'.
2 'Und weil Dasein wesenhaft je seine Möglichkeit ist, kann dieses Seiende in seinem Sein sich selbst "wählen", gewinnen, es kann sich verlieren, bzw. nie und our "scheinbar" gewinnen. Verloren habenkann es sich our und noch nicht sich gewonnen haben kann es nur, sofern es seinem Wesen nach mögliches eigentliches, das heisst sich zueigen ist.' Older editions have 'je wesenhaft' and 'zueigenes'. The connection between 'eigentlich' ('authentic', 'real') and 'eigen' ('own') is lost in translation.
3 '... dass Dasein überhaupt durch Jemeinigkeit bestimmt ist.'