Against Two Letters of the Pelagians 84In What Sense the Righteousness of Man in This Life is Said to Be Perfect.

From this it results that the virtue which is now in the righteous man is named perfect up to this point, that to its perfection belong both the true knowledge and humble confession of even imperfection itself. For, in respect to this infirmity, that little righteousness of man's is perfect according to its measure, when it understands even what it lacks. And therefore the apostle calls himself both perfect and imperfect,--imperfect, to wit, in the thought of how much is wanting to him for the righteousness for the fulness of which he is still hungering and thirsting; but perfect in that he does not blush to confess his own imperfection, and goes forward in good that he may attain. As we can say that the wayfarer is perfect whose approach is well forwarded, although his intention is not carried out unless his arrival be actually effected. Therefore, when he had said, "According to the righteousness which is in the law, I am one who has been without blame," he immediately added, "What things were gain to me, those I counted but loss for Christ's sake. Yea, doubtless, and I count all things to be loss for the sake of the eminent knowledge of Christ Jesus our Lord: for whose sake I have believed all things not only to be losses, but I have thought them to be even as dung, that I might gain Christ and be found in Him, not having my own righteousness, which is of the law, but that which is by the faith of Christ, the righteousness which is of God in faith." See! the apostle does not, of course, say falsely, that "according to the righteousness which is of the law he was without blame;" and yet those things which were gain to him, he casts away for Christ's sake, and thinks them losses, injuries, dung. And not only these things, but all other things which he mentioned previously; not on account of any kind of knowledge, but, as he himself says, "the eminent knowledge of Christ Jesus our Lord," which, beyond a doubt, he had as yet in faith, but not yet in sight. For then the knowledge of Christ will be eminent, when He shall be so revealed that what is believed is seen. Whence, in another place, he thus says, "For ye have died, and your life is hidden with Christ in God. When Christ, your life, shall appear, then shall ye also appear with Him in glory." Hence, also, the Lord Himself says, "He who loveth me shall be loved of my Father, and I will love him, and will manifest myself to him." Hence John the Evangelist says, "Beloved, now are we the sons of God, and it has not yet appeared what we shall be: but we know, that when He shall appear, we shall be like Him; for we shall see Him as He is." Then shall the knowledge of Christ be eminent. For now it is, as it were, hidden away in faith; but it does not yet appear eminent in sight.