"Heidegger's Sein und Zeit [Being and Time]... develops a "fundamental ontology" according to the modes in which the self "exists,"... and originates... several meanings of Being...explicated in a number of fundamental categories... [i.e.,] "existentials"... functional structures of the active movement of inner time by which a "world" is entertained and the self [is] originated as a continuous event. The "existentials" have... a profoundly temporal meaning... [i.e.,] categories of internal or mental time, the true dimension of existence... must exhibit, and distribute between them, the three horizons of time—past, present, and future... [I]n the classical... "table of categories"... the column under... "present" remains practically empty... For the existentially "genuine" present is the present of the "situation," which is wholly defined in terms of the self's relation to its "future" and "past." It flashes up... in the light of decision, when the projected "future" reacts upon the given "past" (Geworfenheit) and in this meeting constitutes what Heidegger calls the "moment" (Augenblick): moment, not duration, is the temporal mode of this "present"—a creature of the other two horizons of time, a function of their ceaseless dynamics, and no independent dimension to dwell in. ...a derivative and "deficient" mode of existence. ...[A]ll the relevant categories of existence... having to do with the possible authenticity of selfhood, fall in correlate pairs under... either past or future... No present remains for genuine existence to repose in. Leaping off... from its past, existence projects itself into the future; faces its ultimate limit, death; returns from this eschatological glimpse of nothingness... [T]here is no present to dwell in, only the crisis between past and future... balanced on the razor's edge of decision which thrusts ahead."