Being is only Being for Dasein - Martin Heidegger

Kant speaks of the "thing-in-itself" (Ding an sich) in order to distinguish it from the "thing-for-us" (Ding fur uns), that is, as a "phenomenon." A thing-in-itself is that which is not approachable through experience as are the rocks, plants, and animals. Every thing-for-us is as a thing and also a thing-in-itself, which means that it is recognized absolutely withing the absolute knowledge of God. But not every thing-in-itself is also a thing-for-us: God, for instance, is a thing-in-itself, as Kant uses the word, according to the meaning of Christian theology. p. 5

For anyone who at the end of Western philosophy can and must still question philosophically, the decisive question is no longer merely “What basic character do beings manifest?” or “How may the being of beings be characterized?” but “What is this ‘being’ itself?” The decisive question is that of “the meaning of being,” not merely that of the being of beings.

Every questioning is a seeking. Every seeking takes its direction beforehand from what is sought. Questioning is a knowing search for beings in their thatness and whatness.