The Six Books of Proclus on the Theology of Plato, Volume 2

For if it sometimes follows the Gods, but sometimes falls from an extension to a divine nature, and participates of intellect and the privation of intellect, it is evident that it is alternatively conversant with generation and the Gods. For since it is not for an infinite time with the Gods, it will not for the whole of the following time be conversant with bodies. For that which has not a temporal beginning will never have an end; and that which never has an end is necessarily without a beginning. It remains, therefore, that every partial soul must make periods of ascents from, and of descents into generation, and that this must be unceasing through an infinite time. Every partial soul, therefore, is able to descend and ascend infinitely. And this never ceases to be the case with all of them.