Freud’s conception of time, which actually harks back to Aristotle’s metaphysics and was carried forth by both Descartes and Kant, pictured time as an infinite succession of discrete “nows” unfolding in linear fashion. Linear time is also the conception of time that underlies scientific method, because it locates the succession of nows in the external world where they can be counted and calculated and the intervals between them measured by a subject who stands outside the time being objectified and studied. Thus, his adoption of linear time was consistent with Freud’s wish for his psychoanalysis to attain the status of a natural or objective science.
Martin Heidegger, by contrast, contended that time resides not in the external world but in us, and that Aristotle’s vision of an infinite succession of nows was an inauthentic evasion of our temporal finitude. Heidegger further claimed that finite human existence in all its modes is intelligible or makes sense only on the basis of its temporal constitution. He, in essence, argued that the whole structure of human existence had to be brought into view—namely, that it could be authentically intelligible only in terms of its stretching along between birth and the possibility of death, between two abysses of nothingness. In contrast to the linear notion of time, the temporality revealed in this stretching along, which Heidegger called “primordial,” “ecstatic,” and “authentic,” is a unity of past, present, and future, with each dimension always transcending itself and pointing toward the other two.