Meditations, Book 11, Section 16

Marcus Aurelius — The Emperor

Seventh, the sins themselves don't really trouble us. They exist only in the minds of those who commit them. What troubles us is our own opinion about those sins. Remove that opinion of yours — the idea that wrongdoing is terrible — and you remove your anger. But how do you remove it? By reasoning with yourself that sin is not shameful. But if shame is not the only real evil, then you will be driven by natural instinct to avoid what seems evil. You will end up doing unjust things yourself — stealing, or anything else — to get what you want in this world.

Marcus Aurelius — The Emperor Original

Seventhly, that it is not the sins and transgressions themselves that trouble us properly; for they have their existence in their minds and understandings only, that commit them; but our own opinions concerning those sins. Remove then, and be content to part with that conceit of thine, that it is a grievous thing, and thou hast removed thine anger. But how should I remove it? How? reasoning with thyself that it is not shameful. For if that which is shameful, be not the only true evil that is, thou also wilt be driven whilest thou doest follow the common instinct of nature, to avoid that which is evil, to commit many unjust things, and to become a thief, and anything, that will make to the attainment of thy intended worldly ends.