Psalms 16:7

"I will bless the Lord, who has given Me understanding" [Psalm 16:7]: whereby this inheritance may be seen and possessed. "Yea moreover too even unto night my reins have chastened Me." Yea besides understanding, even unto death, My inferior part, the assumption of flesh, has instructed Me, that I might experience the darkness of mortality, which that understanding has not.

I will bless the Lord who has given me understanding: moreover even until night my reins have rebuked me. He who speaks below, "My flesh shall rest in hope, for you will not leave my soul in hell, nor will you give your holy one to see corruption," consistently now too says: I will bless the Lord who has given me understanding, moreover even until night my reins have rebuked me. For he who is Wisdom, how does he receive understanding? But because "Jesus advanced in age and wisdom and grace before God and men," the Son was instructed not so much by the Father as the man was instructed by his own divinity. Hence too, concerning him who flowered from the root of Jesse, there is the prophet's oracle: "The Spirit of the Lord shall rest upon him, the Spirit of wisdom and of understanding." Which indeed, for beating back the madness of the Arian heresy, Aquila and Theodotion translated better, saying: "I will bless the Lord my counselor"; so that the Father did not so much give the Son wisdom and understanding which he did not have before, as join his own counsel to the Son's judgment. So that, just as in Proverbs Wisdom says that she was a counselor to God when he rejoiced in the completed world, and she rejoiced in herself daily; so also that same Wisdom, in the fact that he assumed a human body, that he died and rose again, shows that he was not without the Father's counsel, but according to that saying, "That I might do your will, my God, I willed it." But this too which follows, "Moreover even until night my reins have instructed me," must be taken thus, that we understand "reins" for hidden thoughts and deep affection, which is properly an idiom (idiōma) of the Scriptures. For as far as is in my memory, neither in any of the philosophers nor among the rhetoricians, nor among the poets, nor even among the physicians themselves, who promise a knowledge of the nature of bodies, do I recall ever having read that "reins" are put for the understanding and for deep thought. But Scripture uses this custom, so that when it wishes to indicate something secret and hidden or mystical, it says, "God who searches hearts and reins"; so that, since the heart is secret, the reins are the more secret parts of the heart. In Wisdom too, which is inscribed with the title of Solomon, I have found written: "God is the witness of his reins, and the true beholder of his heart, and…