Fragments that Remain of the Lost Writings of Proclus, by Thomas Taylor, , at sacred-texts.com
IF the soul of the universe is unbegotten and incorruptible, the world also is unbegotten and incorruptible. For the soul of the world, and likewise every soul, is essentially self-motive; but every thing self-motive is the fountain and principle of motion. If, therefore, the soul of the universe is perpetual, it is necessary that the universe should always be moved by this soul. For as the universe was not moved by the motion of soul, either prior or posterior to soul, it is not possible that soul should not be the principle of its motion, since it is essentially self-motive, and on this account is the principle of motion. Moreover, soul, through being self-motive, is unbegotten and incorruptible. The universe, therefore, is un-begotten and incorruptible. Hence it is evident that every [rational soul] first ascends into a perpetual body [as into a vehicle], and always moves this body. * And likewise, when it is in corruptible bodies, it moves them, though the bodies which are perpetually moved by it.
46:* Concerning this vehicle of the soul, which is ethereal, ace my Translation of the Fifth Book of Proclus on the Timæus of Plato.