Enneads II.2: About the Movement of the Heavens
How Other Beings Move.[314]
2. How do the other beings move? As none of them is the whole, but only a part, consequently, each finds itself situated in a particular place. On the contrary, the heavens are the whole; they constitute the place which excludes nothing, because it is the universe. As to the law according to which men move, each of them, considered in his dependence towards the universe, is a part of all; considered in himself, he is a whole.
Now, if the heavens possess the Soul, wherever they are, what urges them to move in a circle? Surely because the Soul is not exclusively in a determinate place (and the world does not exclusively in one place desire to possess her). Besides, if the power of the Soul revolve around the centre, it is once more evident that the heavens would move in a circle.