A. Is it I or you who go too far? You revive questions already settled, and do not understand that likeness is one thing, equality another; that the former is a painting, the latter, reality. A real horse courses over the plains; the painted one with his chariot does not leave the wall. The Arians do not allow to the Son of God what you give to every man. Some do not dare to confess the perfect humanity of Christ, lest they should be compelled to accept the belief that He had the sins of a man as though the Creator were unequal to the act of creating, and the title Son of Man were co-extensive with the title Son of God. So either set me something else to answer, or lay aside pride and give glory to God.
C. You forget a former answer of yours, and have been so busy forging your chain of argument, and careering through the wide fields of Scripture, like a horse that has slipped its bridle, that you have not said a single word about the main point. Your forgetfulness is a pretext for escaping the necessity of a reply. It was foolish in me to concede to you for the nonce what you asked, and to suppose that you would voluntarily give up what you had received, and would not need a reminder to make you pay what you owed.
A. If I mistake not, it was the question of possible commands of which I deferred the answer. Pray proceed as you think best.
21. C. The commands which God has given are either possible or impossible. If possible, it is in our power to do them, if we choose. If impossible, we cannot be held guilty for omitting duties which it is not given us to fulfill. Hence it results that, whether God has given possible or impossible commands, a man can be without sin if he chooses.
A. I beg your patient attention, for what we seek is not victory over an opponent, but the triumph of truth over falsehood. God has put within the power of mankind all arts, for we see that a vast number of men have mastered them. To pass over those which the Greeks call βάναυσοι, as we may say, the manual arts, I will instance grammar, rhetoric, the three sorts of philosophy— physics, ethics, logic— geometry also, and astronomy, astrology, arithmetic, music, which are also parts of philosophy; medicine, too, in its threefold division— theory, investigation, practice; a knowledge of law in general and of particular enactments. Which of us, however clever he may be, will be able to understand them all, when the most eloquent of orators, discussing rhetoric and jurisprudence, said: “A few may excel in one, in both no one can.” You see, then, that God has commanded what is possible, and yet, that no one can by nature attain to what is possible. Similarly he has given different rules and various virtues, all of which we cannot possess at the same time. Hence it happens that a virtue which in one person takes the chief place, or is found in perfection, in another is but partial; and yet, he is not to blame who has not all excellence, nor is he condemned for lacking that which he has not; but he is justified through what he does possess. The Apostle described the character of a bishop when he wrote to Timothy, “The bishop, therefore, must be without reproach, the husband of one wife, temperate, modest, orderly, given to hospitality, apt to teach; no brawler, no striker; but gentle, not contentious, no lover of money; one that rules well his own house, having his children in subjection with all modesty.” And again, “Not a novice, lest, being puffed up, he fall into the condemnation of the devil. Moreover, he must have good testimony from them that are without, lest he fall into reproach and the snare of the devil.” Writing also to his disciple Titus, he briefly points out what sort of bishops he ought to ordain: “For this cause left I you in Crete, that you should set in order the things that were wanting, and appoint elders in every city, as I gave you charge; if any man is blameless, the husband of one wife, having children that believe, who are not accused of riot or unruly. For the bishop must be blameless (or free from accusation, for so much is conveyed by the original) as God's steward; not self-willed, not soon angry, no brawler, no striker, not greedy of filthy lucre; but given to hospitality, kind, modest, just, holy, temperate; holding to the faithful word which is according to the teaching, that he may be able both to exhort in the sound doctrine, and to convict the gainsayers.” I will not now say anything of the various rules relating to different persons, but will confine myself to the commands connected with the bishop.
Source: Against the Pelagians (New Advent)