Fragments that Remain of the Lost Writings of Proclus, by Thomas Taylor, , at sacred-texts.com
If with respect to light, one kind is material, but another immaterial, according to the difference of those illuminating natures, fire and the sun, the light which is immaterial is, in a certain respect, † corrupted; but material light, in a certain respect, pervades through material substances: for the whole air appears to be no less illuminated by the sun than by the fire that is procured by us. And when clouds pass under the sun, the light is in
one part intercepted, and we do not receive the whole of it. For how can the light which is in the heavens be continuous with that which is in the air? since the latter is corruptible, but the former not. And the one, indeed, is suspended from its proper principle; but the other, if it should so happen, is cut off, and sometimes is not. The corruptible, however, is not continuous with the incorruptible: for two things of this kind are specifically different from each other.
1:* This and the five following Fragments are to be found in the Treatise of Philoponus against Proclus, on the Eternity of the World.
1:† Immaterial light is, in a certain respect, corrupted, because the recipient of it is corruptible; and when this is corrupted, the light which it received departs to its fountain, the sun.