What is the role of the Law in revealing our lusts?

St. Augustine says, “They do not experience this fight within themselves who are not defenders of the virtues and opponents of the vices, nor does anything drive out the evil of concupiscence except the good of continence. There are some who, utterly ignorant of the law of God, do not regard evil concupsicences as enemies, but, wretchedly blind in their slavery to them, even consider themselves as quite happy in sating them rather than quelling them. Indeed, by the Law they know them (‘For through law comes the recognition of sin’ (Rom. 3:20), and ‘I had not known lust,’ he said, ‘unless the law had said, “You shall not lust”’ (Rom. 7:7)) and they are overcome by their attack, because they live subject to the Law

813 St. Augustine of Hippo, On Continence 2.5 (FOTC 16:194–195).

814 St. Augustine of Hippo, On Continence 3.6 (FOTC 16:195–196).

by which what is good is ordered and not given. They do not live subject to grace, which gives through the Holy Spirit that which is ordered by the Law. The Law, therefore, entered into these, ‘that sin might abound’ (cf. Rom. 5:20) in their case. The prohibition increased the concupiscence and rendered it unconquered, that transgression also might be added, which did not exist without the Law, although there was sin. ‘For where there is no law, neither is there transgression’ (Rom. 4:15), Thus when the law prohibits sin, there being no help of grace, it becomes in addition even the strength of the sin committed, whence the Apostle says: ‘And the power of sin is the law’ (1 Cor. 15:56). And it is not to be wondered at that human infirmity has added the strength even from a good law to evil, since for the making of that very law it trusted in its own strength.”⁸¹⁵