Augustine of Hippo — as excerpted in the Catena Aurea on John 12:44-50

“(Tr. liv) If life everlasting is the Son Himself, and the commandment is life everlasting, what is this but saying, I am the commandment of the Father? And in the same way in the following; Whatsoever I speak therefore, even as the Father said unto Me, so I speak, we must not understand, said unto Me, as if words were spoken to the Only Word. The Father spoke to the Son, as He gave life to the Son; not that the Son knew not, or had not, but that He was the Son. What is meant by, as He said unto Me, so I speak, but that I am the Word who speaks. The Father is true, the Son is truth: the True, begat the Truth. What then could He say to the Truth, if the Truth was perfect from the beginning, and no new truth could be added to Him? That He spake to the Truth then, means that He begat the Truth.”