For the heavenly Powers are not naturally holy, but according to the analogy of divine love they receive their measure of sanctification. And as iron placed in the fire does not cease to be iron, though by the violent application of the flame, both in effect and appearance, it passes into fire; so also the Powers on high, from their participation in that which is naturally holy, have a holiness implanted in them. For Satan had not fallen, if by nature he had been unsusceptible of evil.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: adv. Eunom. l. 3.