Man's state, indeed, is neither that of God nor that of things. He is not simply carried forward on an ordered stream of becoming like the rest of the physical world; he is aware that he stands in the midst of it and grasps in thought the flux of becoming itself. Successive instants, that would otherwise simply arrive and pass away into the void, are gathered up and held in his memory, which thus constructs a duration, just as the sense of sight gathers up dispersed matter into a framework of space. By the mere fact that he remembers, man partially redeems the world from the steam of becoming that sweeps it along and redeems himself along with it. In thinking the universe, and in thinking ourselves, we give birth to an order of being which is a kind of intermediary between the mere instantaneity of the being of bodies and the eternal permanence of God. But beneath the frail stability of his memory, which would founder into nothingness in its turn did not God support and stabilize it, man himself passes away. Wherefore, far from ignoring the fact that all things change, Christian thought felt almost to anguish the tragic character of the instant.-- Etienne Gilson, p. 386. Spirit of Medieval Philosophy
For the instant alone is real; here it is that thought gathers up the debris saved from the shipwreck of the past, herein live all of its anticipations of the future, so that this precarious image of a true permanence that memory extends over the flux of matter, is itself borne on by that flux, and with it all that it would save from collapse into pure nought. Thus the past escapes death only in an instant of a thought that endures, but the in-stans is something that at once stands in the present and presses on toward the future where likewise it will find no resting-place; and at last an abrupt interruption will close a history and fix a destiny forever.