Surely after that I was turned, I repented; and after that I was instructed, I smote upon my thigh: I was ashamed, yea, even confounded, because I did bear the reproach of my youth. —Jeremiah 31:19
“We hence learn how blind the Papists are, who, speaking of repentance, hold that man, through his own free-will, returns to God; and on this point is our greatest contest with them at this day. But the Prophet briefly determines the whole question; for, as he had said before, that men cannot turn except God turns them, he now adds, that he had found this to be really the fact, that people had never become conscious of their sins though God had grievously punished them until they were turned, not by their own free-will, but by the hidden working and influence of the Holy Spirit; ‘after thou has turned me, I repented.’ The meaning is, that men never entertain a real hatred towards sin, unless God illuminates their minds and changes their hearts; for what is the turning or conversion of which the Prophet speaks? It is the renewal of the mind and heart. For let its definition be fetched, as they say, from what is contrary to it; what is turning away? It is the alienation of the mind and heart from God. It then follows that when we turn we are converted, we are renewed in knowledge, and then in heart, or in our affections; both of which the Prophet ascribes to the grace of God, for he says that the people repented not of their sins until they were turned or converted, that is, until they were renewed both in mind and heart.
—John Calvin on repentance, Jeremiah 31:19 Commentary on the Prophet Jeremiah & The Lamentations (Vol. IV, Baker Book House, Grand Rapids, MI, p. 102.)