Plotinos: Complete Works, v. 2 In Chronological Order,...

17. From the intelligible world souls first descend into the heaven. For if the heaven is the best part of the sense-world, it must be nearest to the limits of the intelligible world. The celestial bodies are therefore the first that receive the souls, being most fitted to receive them. The terrestrial body is animated the last, and it is suited to the reception of an inferior soul only, because it is more distant from the incorporeal nature. All souls first illuminate the sky, and radiate from it their first and purest rays; the remainder is lit up by inferior powers. There are souls which, descending lower, illuminate inferior things; but they do not gain anything in getting so far from their origin.