Quote 10 31

Among material beings, it occurs that those which are lesser become greater through participation in the higher order of things as, for example, when they are bathed in light or stimulated by warmth. Rational, incorporeal beings also become enhanced through their participation in the Creator when, for example, they are joined to Him by pure and holy love. If, however, they lack this, they return to darkness or even become atrophied.

Epistula 140, 23, 56.