Sicut in rebus naturalibus sunt propria principia activa in unoquoque genere, licet Deus sit causa agens prima et communis, ita etiam requiritur proprium lumen intellectuale in homine, quamvis Deus sit prima lux omnes communiter illuminans.
"Just as in a natural thing of whatever kind there are its own active principles, although God is the primary and common agent cause, so also there must be in man his own intellectual light, however much God may be the first light illuminating all in common."
De anima art. 4 ad 7