Ethics

De Officiis (On Duties)

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Cicero

44 BC

De Officiis is Cicero's final and most influential philosophical work, written in the last months of his life as a letter to his son Marcus studying in Athens. Drawing on the Stoic philosopher Panaetius, Cicero examines three questions: what is morally right (honestum), what is expedient (utile), and what to do when they appear to conflict. The book argues that genuine moral virtue is always compatible with true advantage — the apparent conflict between honesty and self-interest is always a sign of muddled thinking about what advantage really means. Book I catalogues the four cardinal virtues (wisdom, justice, courage, and temperance) and their requirements; Book II analyses how reputation and honour translate into practical power; Book III, Cicero's most original contribution, examines famous cases in which expediency seems to override duty and systematically demonstrates that they do not. De Officiis became one of the most widely read books of the Western tradition — Erasmus called it "more useful than any other book" — shaping political philosophy from Augustine through Machiavelli, Grotius, and Adam Smith.