Thomas Aquinas — on Rom 7:16 (Commentary on Romans)

“Then when he says, now if I do, he concludes from the aforementioned condition of man that the law is good, saying, now if I do that which I will not. No matter which of the aforementioned ways is taken, by the very fact that I hate evil I consent to the law, that it is good in forbidding evil which I naturally do not want. For it is clear that man's inclination in keeping with reason to will the good and flee evil is in accord with nature or grace; and each is good. Hence, the law also, which agrees with this inclination by commanding what is good and forbidding what is evil, is good for the same reason: I give you good precepts; do not forsake my teaching (Ps 4:2).”