Augustine of Hippo : What does it mean what Moses says the Lord told him about the Hebrew people with these words: Who will make his heart so be that they fear me and keep my commandments !? Does the Lord intend to say that we must understand here that this favor is granted by his grace, namely, that the justice of God be in men by faith, not as their own as if it came from the law? (Cf Philip 3,9) This idea it is indicated by the text of the prophet, when the Lord says: I will take away the heart of stone and give you a heart of flesh (Ez 11,19; 36,26). And this is said according to the meaning of the word meat and that does not have the word stone, because this word is used in a metaphorical sense. The prophet says this in another place: Behold, the days are coming, says the Lord, when I will conclude a new covenant with the house of Israel and with the house of Judah; not like the covenant I made with his parents the day I took his hand to bring them out of the land of Egypt. Because this will be the covenant I made with them: After those days I will put my laws in his heart and write them on his mind, and I will no longer remember his iniquities or his sins (Jr 38 (31), 31.32.33.34). Here distinguishes the new alliance from the old one, because in the old one the law was given on stone tablets; in the new, however, it occurred in hearts, which is done by grace. That is why the Apostle also says: Not on tablets of stone, but on the tables of flesh of the heart. And in another place he says: He made us qualified ministers for the new covenant, not of the letter, but of the Spirit (2 Corinthians 3,3.6). — QUESTIONS ON DEUTERONOMY, Q. 11 (tr. J. Litteral, draft)