if only in order to make clear that the essence of concern with time does not lie in the application of numerical procedures in dating. Thus in time-reckoning, what is decisive from an existential-ontological standpoint is not to be seen in the quantification of time but must be conceived more primordially in terms of the temporality of the Dasein which reckons with time.
'Public time' turns out to be the kind of time 'in which' the ready-to-hand and the present-at-hand within-the-world are encountered. This requires that these entities which are not of the character of Dasein, shall be called entities "within-time". The Interpretation of within-time-ness gives us a more primordial insight into the essence of 'public time' and likewise makes it possible to define its 'Being'.
The Being of Dasein is care. This entity exists fallingly as something that has been thrown. Abandoned to the 'world' which is discovered with its factical "there", and concernfully submitted to it, Dasein awaits its potentiality-for-Being-in-the-world; it awaits it in such a manner that it 'reckons' on and 'reckons' with whatever has an involvement for the sake of this potentiality-for-Being—an involvement which, in the end, is a distinctive one.1 Everyday circumspective Being-in-the-world needs the possibility of sight (and this means that it needs brightness) if it is to deal concernfully with what is ready-to-hand within the present-at-hand. With the factical disclosedness of Dasein's world, Nature has been uncovered for Dasein. In its thrownness Dasein has been surrendered to the changes of day and night. Day with its brightness gives it the possibility of sight; night takes this away.
Dasein awaits with circumspective concern the possibility of sight, and it understands itself in terms of its daily work; in thus awaiting and understanding, it gives its time with the 'then, when it dawns ...'2 The 'then' with which Dasein concerns itself gets dated in terms of something which is connected with getting bright, and which is connected with it in the closest kind of environmental involvement—namely, the rising of the sun. "Then, when the sun rises, it is time for so and so.'' Thus Dasein dates the time which it must take, and dates it in terms of something it encounters within the world and within the horizon of its abandonment to the world—in terms of something encountered as having a distinctive involvement for its circumspective potentiality-for-Being-in-the-world. Concern makes use of the 'Being-ready-to-hand' of the sun, which sheds forth light and warmth. The sun dates the time which is interpreted in concern. [413] In terms of this dating arises the 'most natural' measure of time—the day.
1 '... dass es mit dem und auf das "rechnet", womit es umwillen dieses Seinkönnens eine am Ende ausgezeichnete Bewandtnis hat.'
2 '... mit dem "dann, wann es tagt" ...'