belongs to it; this means that because Dasein's Being is Being-with, its understanding of Being already implies the understanding of Others. This understanding, like any understanding, is not an acquaintance derived from knowledge about them, but a primordially existential kind of Being, which, more than anything else, makes such knowledge and acquaintance possible.1 Knowing oneself [Sichkennen] is grounded in [124] Being-with, which understands primordially. It operates proximally in accordance with the kind of Being which is closest to us—Being-in-the-world as Being-with; and it does so by an acquaintance with that which Dasein, along with the Others, comes across in its environmental circumspection and concerns itself with—an acquaintance in which Dasein understands. Solicitous concern is understood in terms of what we are concerned with, and along with our understanding of it. Thus in concernful solicitude the Other is proximally disclosed.
But because solicitude dwells proximally and for the most part in the deficient or at least the Indifferent modes (in the indifference of passing one another by), the kind of knowing-oneself which is essential and closest, demands that one become acquainted with oneself.2 And when, indeed, one's knowing-oneself gets lost in such ways as aloofness, hiding oneself away, or putting on a disguise, Being-with-one-another must follow special routes of its own in order to come close to Others, or even to 'see through them' ["hinter sie" zu kommen].
But just as opening oneself up [Sichoffenbaren] or closing oneself off is grounded in one's having Being-with-one-another as one's kind of Being at the time, and indeed is nothing else but this, even the explicit disclosure of the Other in solicitude grows only out of one's primarily Being with him in each case. Such a disclosure of the Other (which is indeed thematic, but not in the manner of theoretical psychology) easily becomes the phenomenon which proximally comes to view when one considers the theoretical problematic of understanding the 'psychical life of Others' ["fremden Seelenlebens"]. In this phenomenally 'proximal' manner it thus presents a way of Being with one another understandingly; but at the same time it gets taken as that which, primordially and 'in the beginning', constitutes Being towards Others and makes it possible at all.
1 'Dieses Verstehen ist, wie Verstehen überhaupt, nicht eine aus Erkennen erwachsene Kenntnis, sondern eine ursprünglich existenziale Seinsart die Erkennen und Kenntnis allererst möglich macht'. While we have here translated 'Kenntnis' as 'acquaintance' and 'Erkennen' as 'knowledge about', these terms must not be understood in the special senses exploited by Lord Russell and C. I. Lewis. The 'acquaintance' here involved is of the kind which may be acquired whenever one is well informed about something, whether one has any direct contact with it or not.
2 '... bedarf das nächste und wesenhafte Sichkennen eines Sichkennenlernens.' 'Sichkennen' ('knowing oneself') is to be distinguished sharply from 'Selbsterkenntnis' ('knowledge of the Self'), which will be discussed on H. 146. See our note 1, p. 186.
3 'Wie dem Besorgen als Weise des Entdeckens des Zuhandenen die Umsicht zugehört, so ist die Fürsorge geleitet durch die Rücksicht und Nachsicht.' Heidegger is here calling attention to the etymological kinship of the three words which he italicizes, each of which stands for a special kind of sight or seeing ('Sicht').
The italicization of 'Umsicht' ('circumspection') is introduced in the newer editions.
4 '... bis zur Rücksichtslosigkeit und dem Nachsehen, das die Gleichgültigkeit leitet.' This passage is ambiguous both syntactically and semantically. It is not clear, for instance, whether the subject of the relative clause is 'die Gleichgültigkeit' or the pronoun 'das', though we prefer the former interpretation. 'Nachsehen', which is etymologically akin to 'Nachsicht', means to 'inspect' or 'check' something; but it often means to do this in a very perfunctory manner, and this latter sense may well be the one which Heidegger has in mind.