In the first seven books Augustine searches the scriptures for clues to understanding the Trinity and then defends the orthodox statement of the doctrine against the Arians. In the last eight books Augustine seeks to understand the mystery of the divine Trinity by observing an analogous trinity in the image of God, which is the human mind; and in so doing, he also suggests a program for the serious Christian of spiritual self-discovery and renewal.
“Thus he goes on to make this very point: For just as the Father has life in himself, so he gave the Son also to have life in himself (Jn 5:26). Then he comes to the sight of his splendor in which he will come to judgment, a sight that will be shared by wicked and just alike: and he also gave him authority, he continues, to do judgment, because he is the Son of man (Jn 5:27).” (Page 101)
“No, in this matter we have the authority of God’s scriptures, which our minds should not stray from, the solid foundation of divine utterances which we must not leave, to plunge down the steep slopes of our own guesswork into places where neither our senses can guide us nor the clear reason of truth can enlighten us.” (Page 167)
“And so it is not without reason that scripture says both; that the Son is equal to the Father and that the Father is greater than the Son. The one is to be understood in virtue of the form of God, the other in virtue of the form of a servant, without any confusion.” (Page 79)
“So there need be no hesitation from anyone in taking this to mean that what the Father is greater than is the form of a servant, whereas the Son is his equal in the form of God.” (Page 80)
“His ascension to the Father signified his being seen in his equality with the Father, that being the ultimate vision which suffices us.” (Page 86)