People who know no self-restraint lead stormy and disordered lives, passing their time in a state of fear commensurate with the injuries they do to others, never able to relax. After every act they tremble, paralyzed, their consciences continually demanding an answer, not allowing them to get on with other things. To expect punishment is to suffer it; and to earn it is to expect it. Where there is a bad conscience, some circumstance or other may provide one with impunity, but never with freedom from anxiety; for a person takes the attitude that even if he isn’t found out, there’s always the possibility of it. His sleep is troubled. Whenever he talks about someone else’s misdeed he thinks of his own, which seems to him all to inadequately hidden, all to inadequately blotted out of people’s memories. A guilty person sometimes has the luck to escape detection, but never to feel sure of it.
-Seneca, Letters to Lucilius, Letter CV.