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

For every body is moveable by something else, but is not naturally adapted to move itself, but by the presence of soul is moved of itself, lives on account of soul, and when soul is present, is in a certain respect self-moveable, but when it is absent is alter-moveable, as deriving this nature from soul which is allotted a self-moveable essence. For to whatever nature soul is present, to this it imparts self-motion. It is however, by a much greater priority that which it imparts by its very being. Hence, it is beyond bodies, which become self-moveable by participation as being essentially self-moveable.

Again however, soul which is moved from itself, has an order secondary to the immoveable nature, which subsists immoveable according to energy. Because of all the natures that are moved, the self-moveable essence is the leader; but of all that move, the immoveable is the leader. If therefore soul being moved from itself, moves other things, it is necessary that prior to it, there should be that which moves immoveably. But intellect moves being immoveable, and energizing always with an invariable sameness of subsistence. For soul on account of intellect participates of perpetual intellectual energy, just as body on account of soul possesses the power of moving itself. For if perpetual intellection was primarily in soul, it would be inherent in all souls, in the same manner as the self-motive power. Hence, perpetual intellection is not primarily in soul. It is necessary therefore, that prior to it, there should be that which is primarily intellective. And hence, intellect is prior to souls.

Moreover, the one is prior to intellect. For intellect though it is immoveable yet is not the one; for it intellectually perceives itself, and energizes about itself. And of the one indeed, all beings in whatever way they may exist, participate; but all beings do not participate of intellect. For those beings to whom intellect is present by participation, necessarily participate of knowledge; because intellectual knowledge is the principle and first cause of the gnostic energy. The one therefore, is beyond intellect; and there is no longer any thing else beyond the one. For the one and the good are the same. But the good, as has been demonstrated, is the principle of all things.