Only Your Own Vice Can Truly Harm You

Marcus draws a sharp line around what genuinely damages a person. External events — illness, poverty, insult, even death — are not evils; they're indifferent. The only real harm to a human being is to become unjust, cowardly, intemperate, or dishonest — that is, to damage your own character. "No one can hinder your own good," he says; no one can force you to be a worse person.

This flips the usual scorecard. The one who wrongs you harms themselves, not you, because they corrupt their own soul; you are only harmed if you respond by corrupting yours. Retaliation, resentment, and rage are the actual injuries — self-inflicted.

So Marcus's counsel is radical self-responsibility: "The best revenge is not to be like your enemy." Keep your inner citadel — your ruling mind — unbreached, and nothing outside can defeat you.