(CG 2/96). That Intelligences subsisting apart do not gather their Knowledge?... (Book 2: God The Origin of Creatures) (Summa Contra Gentiles) (Aquinas, Thomas, St.)

What is sometimes in actuality, sometimes in potentiality, is measured by time. But the mind of an intelligence subsisting apart is above time (Chap. XCVI). Therefore it is not at times in the act of understanding and at times not.

2. Every living substance has by its nature some actual vital activity always going on in it, although other activities are potential: thus animals are always repairing waste by assimilation of nourishment, though they do not always feel. But separately subsisting intelligences are living substances, and have no other vital activity but that of understanding. Therefore by their nature they must be always actually understanding.