Didascalicon, Book I (chapters 2-13): the origin of the arts and the division of philosophy
Chapter VIII. On the superlunary and sublunary world
Hence it is that the mathematicians divided the world into two parts: namely into that part which is from the circle of the moon upward, and that which is below. And the superlunary world, because there all things stand by a primordial law, they called nature; the sublunary, the work of nature, namely of the higher; because the kinds of all living things, which are quickened in it by the infusion of vital spirit, receive from the higher through invisible channels an infused nourishment, not only that they may grow by being born, but also that they may subsist by being fed. They also called the same higher world time, on account of the course and motion of the stars that are in it; the lower, temporal, because it is moved according to the higher motions. Likewise they called the superlunary world, on account of the perpetual tranquillity of light and rest, Elysium; and this lower world, on account of the inconstancy and confusion of things, tossed as by waves, they called the infernal.
We have pursued these matters a little more broadly in order to show that man, in that part in which he shares in mutability, is also subject to necessity; but in that part in which he is immortal, he is akin to divinity. From this can be gathered what was said above: that the intention of all human actions converges to this end, that the image of our likeness be restored in us, or that provision be made for the necessities of this life, which, the more easily it can be hurt by adversities, the more it needs to be cherished and preserved.