Letters 94.37

“Still,” it is objected, “laws do not always make us do what we ought to do; and what else are laws than precepts mingled with threats?” Now first of all, the laws do not persuade just because they threaten; precepts, however, instead of coercing, correct men by pleading. Again, laws frighten one out of communicating crime, while precepts urge a man on to his duty. Besides, the laws also are of assistance towards good conduct, at any rate if they instruct as well as command.

Seneca, Letters to Lucilius 94.37, translated by Richard Mott Gummere