Whether the natural law can be blotted out from the heart of man? (Thomas Aquinas)

Augustine says (Confess. ii): “Thy law is written in the hearts of men, which iniquity itself effaces not.” But the law which is written in men’s hearts is the natural law. Therefore the natural law cannot be blotted out.

Saint Thomas Aquinas Summa Theologiae Ia IIae, q. 94, a. 6, sed contra.