Augustine has made no mention of this treatise in his book of Retractations; for the reason, no doubt, that it belonged to the collection of the Epistles, for which he designed a separate statement of Retractations. In all the Mss. this work begins with his usual epistolary salutation: "Augustine, to his holy brethren and fellow-bishops Eutropius and Paulus." And yet, by general consent, this epistle has been received as a treatise, not only in those volumes of his works which contain this work, but also in the writings of those ancient authors who quote it. Amongst these, the most renowned and acquainted with Augustine's writings, Possidius (In indiculo, 4) and Fulgentius (Ad Monimum, i. 3) expressly call this work "A Treatise on the Perfection of Man's Righteousness." So far nearly all the Mss. agree, but a few (including the Codd. Audöenensis and Pratellenses) add these words to the general title: "In opposition to those who assert that it is possible for a man to become righteous by his own sole strength." In a Ms. belonging to the Church of Rheims there occurs this inscription: "A Treatise on what are called the definitions of Coelestius." Prosper, in his work against the Collator, ch. 43, advises his reader to read, besides some other of Augustine's "books," that which he wrote "to the priests Paulus and Eutropius in opposition to the questions of Pelagius and Coelestius."
From this passage of Prosper, however, in which he mentions, but with no regard to accurate order, some of the short treatises of Augustine against the Pelagians, nobody could rightly show that this work On the Perfection of Man's Righteousness was later in time than his work On Marriage and Concupiscence, or than the six books against Julianus, which are mentioned previously in the same passage by Prosper. For, indeed, at the conclusion of the present treatise, Augustine hesitates as yet to censure those persons who affirmed that men are living or have lived in this life righteously without any sin at all: their opinion Augustine, in the passage referred to (just as in his treatises On Nature and Grace, n. 3, and On the Spirit and the Letter, nn. 49, 70), does not yet think it necessary stoutly to resist. Nothing had as yet, therefore, been determined on this point; nor were there yet enacted, in opposition to this opinion, the three well-known canons (6-8) of the Council of Carthage, which was held in the year 418. Afterwards, however, on the authority of these canons, he cautions people against the opinion as a pernicious error, as one may see from many passages in his books Against the two Epistles of the Pelagians, especially Book iv. ch. x. (27), where he says: "Let us now consider that third point of theirs, which each individual member of Christ as well as His entire body regards with horror, where they contend that there are in this life, or have been, righteous persons without any sin whatever." Certainly, in the year 414, in an epistle (157) to Hilary, when answering the questions which were then being agitated in Sicily, he expresses himself in the same tone, and almost in the same language, on sinlessness, as that which he employs at the end of this present treatise. "But those persons," says he (in ch. ii. n. 4 of that epistle), "however much one may tolerate them when they affirm that there either are, or have been, men besides the one Saint of saints who have been wholly free from sin; yet when they allege that man's own free will is sufficient for fulfilling the Lord's commandments, even when unassisted by God's grace and the gift of the Holy Spirit for the performance of good works, the idea is altogether worthy of anathema and of perfect detestation." On comparing these words with the conclusion of this treatise before us, nothing will appear more probable than that the work which supplies the refutation of Coelestius' questions, which were also brought over from Sicily, was written not long after the above-mentioned epistle. This work Possidius, in his index, places immediately after the treatise On Nature and Grace, and before the book On the Proceedings of Pelagius. Augustine, however, does not mention this work in his epistle (169) which he addressed to Evodius about the end of the year 415; but he intimates in it that he had published an answer to the Commonitorium of Orosius, wherein that author stated that "the bishops Eutropius and Paulus had already given information to Augustine about certain formidable heresies." Some suppose that this statement refers to the letter which they despatched to Augustine along with Coelestius' propositions. However that be, it is not unreasonable to believe that they, not long after Orosius' arrival in Africa (that is, before the midsummer of the year 415), had sent these propositions to him, and that Augustine soon afterwards wrote back to Eutropius and Paulus a refutation of them, his answer to Orosius having been previously given.
Furthermore, Coelestius, whose name is inscribed in the propositions, "wrote to his parents from his monastery," as Gennadius informs us in his work on Church writers (De Scriptoribus Ecclesiasticis), "before he fell in with the teaching of Pelagius, three letters in the shape of short treatises, necessary for all seekers after God." Afterwards he openly professed the Pelagian heresy, and published a short treatise, in which, besides other topics, he acknowledged in the Church of Carthage that even infants had redemption by being baptized into Christ,-an episcopal decision on the question having been obtained in that city about the commencement of the year 412, as we learn from an epistle to Pope Innocent (amongst the Epistles of Augustine [175, n. 1 and 6]), as well as from the epistle [157, n. 22] which we have referred to above; and from Augustine's work On the Merits of Sins, i. 62, and ii. 59; also from his treatise On Original Sin, 21; and his work Against Julianus, iii. 9. Another work by an anonymous writer, but which was commonly attributed to Coelestius, divided into chapters, is mentioned in the treatise which follows the present one, On the Proceedings of Pelagius; see chapters 29, 30, and 62.There were extant, moreover, in the year 417, several small books or tracts of Coelestius, which Augustine, in his work On the Grace of Christ, 31, 32, and 36, says were produced by Coelestius himself in some ecclesiastical proceedings at Rome under Zosimus. Augustine, at the commencement of the present work On the Perfection of Man's Righteousness, mentions an undoubted work of Coelestius as having been seen by him, from which he discovered that the definitions or propositions therein examined by Augustine were not unsuited to the tone and temper of Coelestius. This was very probably the book which Jerome quotes in his Epistle to Ctesiphon, written in the year 413 or 414. These are Jerome's words: "One of his followers [that is, Pelagius'], who was already in fact become the master and the leader of all that army, and `a vessel of wrath,'237 in opposition to the apostle, runs on through thickets, not of syllogisms, as his admirers are apt to boast, but of solecisms, and philosophizes and disputes to the following effect: `If I do nothing without God's help, and if everything which I shall achieve is owing to His operations solely, then it follows that it is not I who work, but only God's work is to be crowned in me. In vain, therefore, has He conferred on me the power of will, if I am unable to exercise it fully without His incessant help. That volition, indeed, is destroyed which requires the assistance of another. But it is free will which God has given to me; and free it can only remain, if I do whatever I wish. The state of the case then is this: I either use once for all the power which has been bestowed on me, so that free will is preserved; or else, if I require the assistance of another, liberty of decision in me is destroyed.' "