The Institutes, Book 12
The Elders’ Teaching on Gaining Purity
So it is now time to set out, in the very words in which they hand it down, the judgment of the fathers: of those who did not paint the way of perfection and its nature in high-sounding words, but who possessed it in deed and in truth and in the power of their spirit, and passed it on by their own experience and sure example.
They say that no one can be wholly cleansed from sins of the flesh unless he has realized that all his labors and efforts are not enough for so great and perfect an end; and unless he recognizes, taught not by a system handed down to him but by his own feelings and virtues and experience, that it can be gained only by the mercy and help of God. For to win such splendid and lofty prizes of purity and perfection, however great the efforts of fasting and vigils and reading and solitude and retirement applied to it, these will not be enough to secure it by the merit of the efforts and toil themselves. A man’s own efforts and human labors will never make up for the lack of the divine gift, unless it is granted by God’s compassion in answer to his prayer.