Chapter 1 [I.] —The Occasion of Writing This Work; A Thing May Be Capable of Being Done, and Yet May Never Be Done.
After reading the short treatises which I lately drew up for you, my beloved son Marcellinus, about the baptism of infants, and the perfection of man’s righteousness,—how that no one in this life seems either to have attained or to be likely to attain to it, except only the Mediator, who bore humanity in the likeness of sinful flesh, without any sin whatever,—you wrote me in answer that you were embarrassed by the point which I advanced in the second book, that it was possible for a man to be without sin, if he wanted not the will, and was assisted by the aid of God; and yet that except One in whom “all shall be made alive,” no one has ever lived or will live by whom this perfection has been attained whilst living here. It appeared to you absurd to say that anything was possible of which no example ever occurred,—although I suppose you would not hesitate to admit that no camel ever passed through a needle’s eye, and yet He said that even this was possible with God; you may read, too, that twelve thousand legions of angels could possibly have fought for Christ and rescued Him from suffering, but in fact did not; you may read that it was possible for the nations to be exterminated at once out of the land which was given to the children of Israel, and yet that God willed it to be gradually effected. And one may meet with a thousand other incidents, the past or the future possibility of which we might readily admit, and yet be unable to produce any proofs of their having ever really happened. Accordingly, it would not be right for us to deny the possibility of a man’s living without sin, on the ground that amongst men none can be found except Him who is in His nature not man only, but also God, in whom we could prove such perfection of character to have existed.
Chapter 2 [II.]—The Examples Apposite.
Here, perhaps, you will say to me in answer, that the things which I have instanced as not having been realized, although capable of realization, are divine works; whereas a man’s being without sin falls in the range of a man’s own work,—that being indeed his very noblest work which effects a full and perfect righteousness complete in every part; and therefore that it is incredible that no man has ever existed, or is existing, or will exist in this life, who has achieved such a work, if the achievement is possible for a human being. But then you ought to reflect that, although this great work, no doubt, belongs to human agency to accomplish, yet it is also a divine gift, and therefore, not doubt that it is a divine work; “for it is God who worketh in you both to will and to do of His good pleasure.”
Chapter 3.—Theirs is Comparatively a Harmless Error, Who Say that a Man Lives Here Without Sin.
They therefore are not a very dangerous set of persons and they ought to be urged to show, if they are able, that they are themselves such, who hold that man lives or has lived here without any sin whatever. There are indeed passages of Scripture, in which I apprehend it is definitely stated that no man who lives on earth, although enjoying freedom of will, can be found without sin; as, for instance, the place where it is written, “Enter not into judgment with Thy servant, for in Thy sight shall no man living be justified.” If, however, anybody shall have succeeded in showing that this text and the other similar ones ought to be taken in a different sense from their obvious one, and shall have proved that some man or men have spent a sinless life on earth,—whoever does not, not merely refrain from much opposing him, but also does not rejoice with him to the full, is afflicted by extraordinary goads of envy. Moreover, if there neither is, has been, nor will be any man endowed with such perfection of purity (which I am more inclined to believe), and yet it is firmly set forth and thought there is or has been, or is to be,—so far as I can judge, no great error is made, and certainly not a dangerous one, when a man is thus carried away by a certain benevolent feeling; provided that he who thinks so much of another, does not think himself to be such a being, unless he has ascertained that he really and clearly is such.
Chapter 4.—Theirs is a Much More Serious Error, Requiring a Very Vigorous Refutation, Who Deny God’s Grace to Be Necessary.
They, however, must be resisted with the utmost ardor and vigor who suppose that without God’s help, the mere power of the human will in itself, can either perfect righteousness, or advance steadily towards it; and when they begin to be hard pressed about their presumption in asserting that this result can be reached without the divine assistance, they check themselves, and do not venture to utter such an opinion, because they see how impious and insufferable it is. But they allege that such attainments are not made without God’s help on this account, namely, because God both created man with the free choice of his will, and, by giving him commandments, teaches him, Himself, how man ought to live; and indeed assists him, in that He takes away his ignorance by instructing him in the knowledge of what he ought to avoid and to desire in his actions: and thus, by means of the free-will naturally implanted within him, he enters on the way which is pointed out to him, and by persevering in a just and pious course of life, deserves to attain to the blessedness of eternal life.
Chapter 5 [III.]—True Grace is the Gift of the Holy Ghost, Which Kindles in the Soul the Joy and Love of Goodness.
We, however, on our side affirm that the human will is so divinely aided in the pursuit of righteousness, that (in addition to man’s being created with a free-will, and in addition to the teaching by which he is instructed how he ought to live) he receives the Holy Ghost, by whom there is formed in his mind a delight in, and a love of, that supreme and unchangeable good which is God, even now while he is still “walking by faith” and not yet “by sight;”  in order that by this gift to him of the earnest, as it were, of the free gift, he may conceive an ardent desire to cleave to his Maker, and may burn to enter upon the participation in that true light, that it may go well with him from Him to whom he owes his existence. A man’s free-will, indeed, avails for nothing except to sin, if he knows not the way of truth; and even after his duty and his proper aim shall begin to become known to him, unless he also take delight in and feel a love for it, he neither does his duty, nor sets about it, nor lives rightly. Now, in order that such a course may engage our affections, God’s “love is shed abroad in our hearts,” not through the free-will which arises from ourselves, but “through the Holy Ghost, which is given to us.”