Plotinos: Complete Works, v. 1 In Chronological Order,...

13. (18). If intelligible entities are separated from sense objects, how does it happen that the soul descends into a body?88 So long as the soul is a pure and impassible intelligence, so long as she enjoys a purely intellectual life like the other intelligible beings, she dwells among them; for she has neither appetite nor desire. But that part which is inferior to intelligence and which is capable of desires, follows their impulsion, "proceeds" and withdraws from the intelligible world. Wishing to ornament matter on the model of the Ideas she contemplated in Intelligence, in haste to exhibit her fruitfulness, and to manifest the germs she bears within her (as said Plato, in the Banquet89), the soul applies herself to produce and create, and, as result of this application, she is, as it were, orientated (or, in "tension") towards sense-objects. With the universal Soul, the human soul shares the administration of the whole world, without, however, entering it; then, desiring to administer some portion of the world on her own responsibility, she separates from the universal Soul, and passes into a body. But even when she is present with the body, the soul does not devote herself entirely to it, as some part of her always remains outside of it; that is how her intelligence remains impassible.90