Da-sein "is" only where and when the being of truth occurs.
A turning—indeed the turning—which indicates precisely the essence of being itself as the event that oscillates in itself.
In itself the event grounds Da-sein (I.).
Da-sein grounds the event (II.).
Here grounding is reciprocally turning: I. bearing-protruding, II. instituting-projecting (cf. The leap, 144. Beyng and the original strife, p.208f.).
141. The essence of beyng8
The ap-propriation of Da-sein by beyng and the grounding of the truth of being in Da-sein—the turning in the event is not contained exclusively either in the call (the remaining absent) or in the belonging (abandonment by being); nor does it reside in both together. For these two themselves, and both together, are first attained in the oscillation of the event. Within the event, the event itself oscillates in the oscillation.
The trembling of this coming to be of the oscillation in the turning of the event is the most concealed essence of beyng. This concealment is cleared as concealment only in the deepest clearing of the site of the moment. In order to occur essentially in this seldomness and uniqueness, beyng "needs" Da-sein, and Da-sein grounds being human, is its ground, insofar as the human being in withstanding Da-sein grounds Da-sein through steadfastness.
142. The essence of beyng
The trembling of the coming to be of the oscillation in the turning, the appropriation of the belonging, grounding, sheltering Dasein to the intimation—this essential occurrence of beyng is not itself the last god; instead, the essential occurrence of being grounds the sheltering, and thereby the creative preservation, of the god, who pervades beyng with divinity always only in work and sacrifice, deed and thought.
Hence thinking, as inaugural of the other beginning, also may come into the remote nearness of the last god.
It does so through and in its self-grounding history but never in the form of a result, i.e., in the form of a productive mode of representation
8. Cf. The grounding, The essence of truth