194. I ask then, whether He had this knowledge by reason of His Being, or by chance? For all knowledge comes to us either through nature, or by learning. It is supplied by nature, as for instance to a horse to enable it to run, or to a fish to enable it to swim. For they do this without learning. On the other hand, it is by learning that a man is enabled to swim. For he could not do so unless he had learned. Since therefore nature enables dumb animals to do and to know what they have not learned, why should you give an opinion on the Son of God, and say whether He has knowledge by instruction or by nature? If by instruction, then He was not begotten as Wisdom, and gradually began to be perfect, but was not always so. But if He has knowledge by nature, then He was perfect in the beginning, He came forth perfect from the Father; and so needed no foreknowledge of the future.
195. He therefore was not ignorant of the days; for it does not fall to the lot of the Wisdom of God to know in part and in part to be ignorant. For how can He who made all things be ignorant of a part, since it is a less thing to know than to make.
Exposition of the Christian Faith, Book V