Romans 2:15

15. Work of the law… hearts The work of the law may mean either the practice which the law enjoins, or the operation of the law itself. The former makes the clearer sense. The work of the law is the deed or duty marked out by the law. The written law or decalogue is mostly prohibitory; the unwritten law of the heart is positive, enjoining a course and a work. The heart is, as it were, a tablet; and as the non-work was written on the tablet of stone, so the positive work is written on the tablet of the heart.

In the human consciousness a just philosophy finds a standard of right and wrong, a moral sense, which affirms the right and disaffirms its opposite.

Their conscience also Three elements are found here in man’s moral nature: First, a law written on the heart, that is, the natural sense, idea, standard, or rule of right and wrong. Second, the conscience, bearing witness; that is, the moral consciousness testifying whether our volitions or actions, or even our emotions and mental states, agree or disagree with this standard or rule. Third, the accusations, excusations, or commendations, moral judgment, pronouncing the subject condemnable or otherwise. These three elements are at the present day usually comprehended under the complex term conscience.

By the English translation the thoughts are made to accuse or excuse one another; that is, thoughts to accuse thoughts. And this makes the better sense. The moral thought does accuse the wicked thought, feeling, or volition. But commentators generally understand it of thoughts accusing the men themselves.

The existence and power of this conscience is often beautifully and forcibly attested by later classic writers. The Greek historian Polybius says: “No witness is so fearful, no accuser is so terrible, as the conscience dwelling in every individual soul.” The Roman poet Juvenal says: “Do you expect those to escape whom the mind, conscious of direful crime, holds confounded? By night and by day they carry the witness within their own breasts.”