Time

Chronos (χρόνος) is time — the medium of before and after, of duration and succession, in which all becoming unfolds. It gives us 'chronology', 'chronic', and 'chronicle'. The Greeks distinguished it from aiōn, eternity: time is the restless, measured flow; eternity the changeless fullness it imitates.

The moving image of eternity

The classic account is Plato's, in the Timaeus. Time did not always exist; it came to be together with the heavens, when the Demiurge, wishing to make the world yet more like its eternal model, fashioned 'a moving image of eternity' that proceeds according to number. The days, the months, the years, and the wheeling of the planets are the parts of time — eternity counted out in the motion of the sky.

The measure of motion

Aristotle gave a more analytic definition in the Physics: time is 'the number of motion with respect to before and after'. Time is not motion itself but its measurable aspect, that by which we count change; where nothing changes, we mark no time. The Neoplatonists returned time to the life of the Soul — the unfolding in succession of what Intellect holds all at once, so that to rise from time toward eternity is once more the soul's movement toward its source.