Matthew 19:17–18

When Christ said, “If you want to enter into life,” or “keep the commandments,” that man, expecting him to say nothing other than “mine,” asks, “Which?” But he was much mistaken in his hope. Christ did not answer him as he thought, but leads him up to the law — not because the law is perfection (“no one is justified in the law,” according to what is written), but because practice according to the law is a kind of entrance to eternal life, little by little habituating the mind of those being tutored toward what is higher. For “the law has become our tutor unto Christ.” So the law is the beginning of bodily conduct, and Christ is perfection; for the beginning of goods, he says, is to do what is just. The law shows the just; Christ shows the good.

The law taught us to ward off with equals those who want to wrong us (“tooth for tooth” and “eye for eye”); but Christ, releasing us from that balance, leads us to the greater … “To the one who strikes you on the right cheek, turn the other also; and to the one who wants to go to law with you and take your tunic,” he says, “leave him the cloak as well.”