Existing explanations of Time seem to fall into three classes: Time is variously identified with what we know as Movement, with a moved object, and with some phenomenon of Movement: obviously it cannot be Rest or a resting object or any phenomenon of rest, since, in its characteristic idea, it is concerned with change.
Of those that explain it as Movement, some identify it with Absolute Movement [or with the total of Movement], others with that of the All. Those that make it a moved object would identify it with the orb of the All. Those that conceive it as some phenomenon, or some period, of Movement treat it, severally, either as a standard of measure or as something inevitably accompanying Movement, abstract or definite. Enneads III, 7, 7