Chapter 121 — That some evil has the nature of punishment, and not of fault

Just as a defect in voluntary action constitutes the notion of fault and sin, so any lack of good inflicted on account of sin against the will of him on whom the lack is inflicted has the notion of punishment. Punishment is inflicted as a medicine for sin, and also as restoring it to right order. Punishment functions as a medicine inasmuch as fear of punishment deters a man from sinning; that is, a person refrains from doing an inordinate action, which would be pleasing to his will, lest he have to suffer what is opposed to his will. Punishment also restores right order, because by sinning a man exceeds the limits of the natural order, bestowing upon his will more than is right. Hence a return to the order of justice is effected by punishment, whereby some good is withdrawn from the sinner’s will. So clearly a suitable punishment is not assigned for the sin unless the punishment is more contrary to the will than the sin was attractive to it.