Timaeus

And whereas the body of the Heaven is visible, the Soul is herself invisible but partakes in reasoning and in harmony, having come into existence by the agency of the best of things intelligible and ever-existing as the best of things generated. Inasmuch, then, as she is a compound, blended of the natures of the Same and the Other and Being, these three portions, and is proportionately divided and bound together, and revolves back upon herself, whenever she touches anything which has its substance dispersed or anything which has its substance undivided she is moved throughout her whole being and announces what the object is identical with and from what it is different, and in what relation, where and how and when, it comes about that each thing exists and is acted upon by others both in the sphere of the Becoming and in that of the ever-uniform. And her announcement, being identically true concerning both the Other and the Same, is borne through the self-moved without speech or sound; and whenever it is concerned with the sensible, and the circle of the Other moving in straight course proclaims it to the whole of its Soul, opinions and beliefs arise which are firm and true; and again, when it is concerned with the rational, and the circle of the Same, spinning truly, declares the facts, reason and knowledge of necessity result. But should anyone assert that the substance in which these two states arise is something other than Soul, his assertion will be anything rather than the truth. And when the Father that engendered it perceived it in motion and alive, a thing of joy to the eternal gods, He too rejoiced; and being well-pleased He designed to make it resemble its Model still more closely. Accordingly, seeing that that Model is an eternal Living Creature, He set about making this Universe, so far as He could, of a like kind. But inasmuch as the nature of the Living Creature was eternal, this quality it was impossible to attach in its entirety to what is generated; wherefore He planned to make a movable image of Eternity, and, as He set in order the Heaven, of that Eternity which abides in unity He made an eternal image, moving according to number, even that which we have named Time. For simultaneously with the construction of the Heaven He contrived the production of days and nights and months and years, which existed not before the Heaven came into being. And these are all portions of Time; even as Was and Shall be are generated forms of Time, although we apply them wrongly, without noticing, to Eternal Being.