Human being is radically finite; for each and every one of us, death-as-possibility (the uttermost possibility) underlies the horizon of all other possibilities. As such, each and every instance of Dasein is directed towards its death – as the annihilation of its possibilities (death is, so to speak, the impossibility of all Dasein’s possibilities). One of Heidegger’s most important insights in Being and Time (though undoubtedly something appropriated from Kierkegaard), is the fundamental role death, as being-towards-death (Sein-zum-Tode), has for the type of Beings we are. Yet, while we all concede that all “mortals” are defined by their ability-to-die, death itself, as my death, is phenomenologically a first-person experience. Only the “I” of the Dasein has the ability to take up its own genuine anticipation of its death as “my death.” It is on account of this that the dis-closure of the mine-ness of my death makes possible individuation and the becoming itself, at all.
To be clear, “death” in this sense is not to be confused with the existentielle or ontic sense of “demise” – the point of departure whereby life ceases-to-be. But rather, in its existential-ontological context signifying the possibility of Dasein’s having no more possibilities (Dreyfus). What does death as existential-ontological possibility dis-close? Nothing! Or rather, it signifies Dasein’s being-in-the-world as delimited by its ownmost possibility of a nullity. This much is dis-closed in the mood of Anxiety, which reveals that the world of possibilities is, in short, not of my creation – that all possibilities are there for “anyone” and “everyone.” Anxiety is the “mood” that allows Dasein to un-cover (dis-close) its groundless-ness, which in turn isolates and cuts Dasein off from its “normal” un-reflective taking-up of the socially, historically, and culturally determined possibilities that presuppose the shared constellation of meaning of everyday life. The isolation of Dasein from its possibilities brings Dasein into direct confrontation with its un-homeliness (unheimlich); in other words –Dasein’s world and actions, and the possibility of their being intelligible in the shared world of Being-in, vanishes. Dasein thus finds itself paralyzed…incapable of projecting itself into any possibility at all. All possibility becomes equally irrelevant, and thus Dasein, though it still is, is unable to throw itself into any particular definite possibility.