Timaeus

So when each of the bodies whose co-operation was required for the making of Time had arrived in its proper orbit; and when they had been generated as living creatures, having their bodies bound with living bonds, and had learnt their appointed duties; then they kept revolving around the circuit of the Other, which is transverse and passes through the circuit of the Same and is dominated thereby; and part of them moved in a greater, part in a smaller circle, those in the smaller moving more quickly and those in the greater more slowly. And because of the motion of the Same, the stars which revolved most quickly appeared to be overtaken by those which moved most slowly, although in truth they overtook them; for, because of their simultaneous progress in two opposite directions, the motion of the Same, which is the swiftest of all motions, twisted all their circles into spirals and thus caused the body which moves away from it most slowly to appear the nearest. And in order that there might be a clear measure of the relative speeds, slow and quick, with which they travelled round their eight orbits, in that circle which is second from the earth God kindled a light which now we call the Sun, to the end that it might shine, so far as possible, throughout the whole Heaven, and that all the living creatures entitled thereto might participate in number, learning it from the revolution of the Same and Similar. In this wise and for these reasons were generated Night and Day, which are the revolution of the one and most intelligent circuit; and Month, every time that the Moon having completed her own orbit overtakes the Sun; and Year, as often as the Sun has completed his own orbit. Of the other stars the revolutions have not been discovered by men (save for a few out of the many); wherefore they have no names for them, nor do they compute and compare their relative measurements, so that they are not aware, as a rule, that the wanderings of these bodies, which are hard to calculate and of wondrous complexity, constitute Time. Nevertheless, it is still quite possible to perceive that the complete number of Time fulfils the Complete Year when all the eight circuits, with their relative speeds, finish together and come to a head, when measured by the revolution of the Same and Similarly-moving. In this wise and for these reasons were generated all those stars which turn themselves about as they travel through Heaven, to the end that this Universe might be as similar as possible to the perfect and intelligible Living Creature in respect of its imitation of the Eternal Nature thereof. Now in all other respects this World had already, with the birth of Time, been wrought in the similitude of that whereunto it was being likened, but inasmuch as it did not as yet contain generated within it the whole range of living creatures, therein it was still dissimilar. So this part of the work which was still undone He completed by molding it after the nature of the Model. According, then, as Reason perceives Forms existing in the Absolute Living Creature, such and so many as exist therein did He deem that this World also should possess.