How the Desire of the Flesh Helps Us

First, because it is an immediate rebuke of our laziness and carelessness. Like some energetic schoolmaster who never lets us stray from the line of strict discipline, if our carelessness has gone ever so little beyond the bounds of the seriousness that becomes it, it at once rouses us with the goad of desire, scolds us, and calls us back to proper restraint. Second, in the matter of chastity and perfect purity. When by God’s grace we see that we have been kept for some time from defilement of the flesh, we might imagine that we can no longer be disturbed by the movements of the flesh, and so be lifted up and puffed up in our secret hearts, as if we no longer carried about the corruption of the flesh. So that this may not happen, it humbles and checks us, and by its pricks reminds us that we are only human. For while we commonly fall into other kinds of sin, worse and more harmful ones, without much thought, and are not so easily ashamed of committing them, in this one in particular the conscience is especially humbled. Through this illusion it is stung by the memory of passions it has neglected, since it sees plainly that it is made unclean by natural impulses of which it knew nothing while it was still more unclean through spiritual sins. And so, turning back at once to cure its former sluggishness, it is warned both that it ought not to trust in its past attainments of purity, which it sees are lost by ever so small a falling away from the Lord, and that it cannot gain the gift of this purity except by God’s grace alone. For experience itself somehow teaches us that if we are eager to reach lasting perfection of heart, we must constantly strive to gain the virtue of humility. [a]