What then is Time?

Is its course but one way? Or is it like a swift stream, that rolls some things along faster & some slower, leaves, sticks and stones, which may change places, and pass each other by, collide, and combine, even as all are borne along? I sometimes think that we lead many lives between birth and dying, and only one, or perhaps two, are ever known to us consciously; the others pass in parallel, invisible, or they run backward while the one we busy ourselves with runs forward. There is no expressing this in words; only in dreams or in the power of certain stimulants is it possible to experience them—the state where two things can, after all, occupy the same space.

from Lord Byron's Novel: The Evening Land by John Crowley