The answer on the difference between grace and the commands of the law.
Theonas: Your inquiry once more raises before us a question of no small extent. The explanation of which though I know that it cannot be taught to or understood by the inexperienced, yet as far as I can, I will try to set forth in words and briefly to explain, if only your minds will follow up and act upon what we say. For whatever is known not by teaching but by experience, just as it cannot be taught by one without experience, so neither can it be grasped or taken in by the mind of one who has not laid the foundation by a similar study and training. And therefore I think it necessary for us first to inquire somewhat carefully what is the purpose or meaning of the law, and what is the system and perfection of grace, that from this we may succeed in understanding the dominion of sin and how to drive it out. And so the law chiefly commands men to seek the bonds of wedlock, saying: “Blessed is he that hath seed in Sion and an household in Jerusalem;” 2217 and: “Cursed is the barren that hath not borne.” 2218 On the other hand grace invites us to the purity of perpetual chastity, and the undefiled state of blessed virginity, saying: “Blessed are the barren, and the breasts which have not given suck;” and: “he that hateth not father and mother and wife cannot be my disciple;” and this of the Apostle: “It remaineth that they that have wives be as though they had them not.” 2219 The law says: “Thou shalt not delay to offer thy tithes and firstfruits;” grace says: “If thou wilt be perfect, go and sell all that thou hast and give to the poor:” 2220 The law forbids not retaliation for wrongs and vengeance for injuries, saying “An eye for an eye and a tooth for a tooth.” Grace would have our patience proved by the injuries and blows offered to us being redoubled, and bids us be ready to endure twice as much damage; saying: “If a man strike thee on one cheek, offer him the other also; and to him who will contend with thee at the law and take away thy coat, give him thy cloak also.” 2221 The one decrees that we should hate our enemies, the other that we should love them so that it holds that even for them we ought always to pray to God.
Isa. xxxi. 9 (lxx.).516:2218
Cf. Job xxiv. 21.516:2219
S. Luke 23:29, Luke 14:26, 1 Cor. 7:29.516:2220
Exod. 22:29, Matt. 19:21.516:2221
Exod. 21:24, Matt. 5:39, 40.