CHAPTER IX. The Replacement of the Fallen Angels By Elect Men (28-30); The Necessity of Grace (30-32)
28. While some of the angels deserted God in impious pride and were cast into the lowest darkness from the brightness of their heavenly home, the remaining number of the angels persevered in eternal bliss and holiness with God. For these faithful angels were not descended from a single angel, lapsed and damned. Hence, the original evil did not bind them in the fetters of inherited guilt, nor did it hand the whole company over to a deserved punishment, as is the human lot. Instead, when he who became the devil first rose in rebellion with his impious company and was then with them prostrated, the rest of the angels stood fast in pious obedience to the Lord and so received what the others had not had-a sure knowledge of their everlasting security in his unfailing steadfastness.
29. Thus it pleased God, Creator and Governor of the universe, that since the whole multitude of the angels had not perished in this desertion of him, those who had perished would remain forever in perdition, but those who had remained loyal through the revolt should go on rejoicing in the certain knowledge of the bliss forever theirs. From the other part of the rational creation-that is, mankind-although it had perished as a whole through sins and punishments, both original and personal, God had determined that a portion of it would be restored and would fill up the loss which that diabolical disaster had caused in the angelic society. For this is the promise to the saints at the resurrection, that they shall be equal to the angels of God. 
Thus the heavenly Jerusalem, our mother and the commonwealth of God, shall not be defrauded of her full quota of citizens, but perhaps will rule over an even larger number. We know neither the number of holy men nor of the filthy demons, whose places are to be filled by the sons of the holy mother, who seemed barren in the earth, but whose sons will abide time without end in the peace the demons lost. But the number of those citizens, whether those who now belong or those who will in the future, is known to the mind of the Maker, "who calleth into existence things which are not, as though they were,"  and "ordereth all things in measure and number and weight." 
30. But now, can that part of the human race to whom God hath promised deliverance and a place in the eternal Kingdom be restored through the merits of their own works? Of course not! For what good works could a lost soul do except as he had been rescued from his lostness? Could he do this by the determination of his free will? Of course not! For it was in the evil use of his free will that man destroyed himself and his will at the same time. For as a man who kills himself is still alive when he kills himself, but having killed himself is then no longer alive and cannot resuscitate himself after he has destroyed his own life-so also sin which arises from the action of the free will turns out to be victor over the will and the free will is destroyed. "By whom a man is overcome, to this one he then is bound as slave."  This is clearly the judgment of the apostle Peter. And since it is true, I ask you what kind of liberty can one have who is bound as a slave except the liberty that loves to sin?
He serves freely who freely does the will of his master. Accordingly he who is slave to sin is free to sin. But thereafter he will not be free to do right unless he is delivered from the bondage of sin and begins to be the servant of righteousness. This, then, is true liberty: the joy that comes in doing what is right. At the same time, it is also devoted service in obedience to righteous precept.
But how would a man, bound and sold, get back his liberty to do good, unless he could regain it from Him whose voice saith, "If the Son shall make you free, then you will be free indeed"  ? But before this process begins in man, could anyone glory in his good works as if they were acts of his free will, when he is not yet free to act rightly? He could do this only if, puffed up in proud vanity, he were merely boasting. This attitude is what the apostle was reproving when he said, "By grace you have been saved by faith." 
31. And lest men should arrogate to themselves saving faith as their own work and not understand it as a divine gift, the same apostle who says somewhere else that he had "obtained mercy of the Lord to be trustworthy"  makes here an additional comment: "And this is not of yourselves, rather it is a gift of God-not because of works either, lest any man should boast."  But then, lest it be supposed that the faithful are lacking in good works, he added further, "For we are his workmanship, created in Christ Jesus to good works, which God hath prepared beforehand for us to walk in them." 
We are then truly free when God ordereth our lives, that is, formeth and createth us not as men-this he hath already done-but also as good men, which he is now doing by his grace, that we may indeed be new creatures in Christ Jesus.  Accordingly, the prayer: "Create in me a clean heart, O God."  This does not mean, as far as the natural human heart is concerned, that God hath not already created this.
32. Once again, lest anyone glory, if not in his own works, at least in the determination of his free will, as if some merit had originated from him and as if the freedom to do good works had been bestowed on him as a kind of reward, let him hear the same herald of grace, announcing: "For it is God who is at work in you both to will and to do according to his good will."  And, in another place: "It is not therefore a matter of man's willing, or of his running, but of God's showing mercy."  Still, it is obvious that a man who is old enough to exercise his reason cannot believe, hope, or love unless he wills it, nor could he run for the prize of his high calling in God without a decision of his will. In what sense, therefore, is it "not a matter of human willing or running but of God's showing mercy," unless it be that "the will itself is prepared by the Lord," even as it is written?  This saying, therefore, that "it is not a matter of human willing or running but of God's showing mercy," means that the action is from both, that is to say, from the will of man and from the mercy of God. Thus we accept the dictum, "It is not a matter of human willing or running but of God's showing mercy," as if it meant, "The will of man is not sufficient by itself unless there is also the mercy of God." By the same token, the mercy of God is not sufficient by itself unless there is also the will of man. But if we say rightly that "it is not a matter of human willing or running but of God's showing mercy," because the will of man alone is not enough, why, then, is not the contrary rightly said, "It is not a matter of God's showing mercy but of a man's willing," since the mercy of God by itself alone is not enough? Now, actually, no Christian would dare to say, "It is not a matter of God's showing mercy but of man's willing," lest he explicitly contradict the apostle. The conclusion remains, therefore, that this saying: "Not man's willing or running but God's showing mercy," is to be understood to mean that the whole process is credited to God, who both prepareth the will to receive divine aid and aideth the will which has been thus prepared. 
For a man's good will comes before many other gifts from God, but not all of them. One of the gifts it does not antedate is-just itself! Thus in the Sacred Eloquence we read both, "His mercy goes before me,"  and also, "His mercy shall follow me."  It predisposes a man before he wills, to prompt his willing. It follows the act of willing, lest one's will be frustrated. Otherwise, why are we admonished to pray for our enemies,  who are plainly not now willing to live piously, unless it be that God is even now at work in them and in their wills?  Or again, why are we admonished to ask in order to receive, unless it be that He who grants us what we will is he through whom it comes to pass that we will? We pray for enemies, therefore, that the mercy of God should go before them, as it goes before us; we pray for ourselves that his mercy shall follow us.
 Cf. Luke 20:36.
 Rom. 4:17.
 Wis. 11:20.
 II Peter 2:19.
 John 8:36
 Eph. 2:8.
 I Cor. 7:25.
 Eph. 2:8, 9.
 Eph. 2:10.
 Cf. Gal. 6:15; II Cor. 5:17.
 Ps. 51:10.
 Phil. 2:13.
 Rom. 9:16.
 Prov. 8:35 (LXX).
 From the days at Cassiciacum till the very end, Augustine toiled with the mystery of the primacy of God's grace and the reality of human freedom. Of two things he was unwaveringly sure, even though they involved him in a paradox and the appearance of confusion. The first is that God's grace is not only primary but also sufficient as the ground and source of human willing. And against the Pelagians and other detractors from grace, he did not hesitate to insist that grace is irresistible and inviolable. Cf. On Grace and Free Will, 99, 41-43; On the Predestination of the Saints, 19:10; On the Gift of Perseverance, 41; On the Soul and Its Origin, 16; and even the Enchiridion, XXIV, 97. But he never drew from this deterministic emphasis the conclusion that man is unfree and everywhere roundly rejects the not illogical corollary of his theonomism, that man's will counts for little or nothing except as passive agent of God's will. He insists on responsibility on man's part in responding to the initiatives of grace. For this emphasis, which is characteristically directed to the faithful themselves, see On the Psalms, LXVIII, 7-8; On the Gospel of John, Tractate, 53:6-8; and even his severest anti-Pelagian tracts: On Grace and Free Will, 6-8, 10, 31 and On Admonition and Grace, 2-8.
 Ps. 58:11 (Vulgate).
 Ps. 23:6.
 Cf. Matt. 5:44.
 The theme that he had explored in Confessions, Bks. I-IX. See especially Bk. V, Chs. X, XIII; Bk. VII, Ch. VIII; Bk. IX, Ch. I.