On Duties, Book 1 (De Officiis)

On Duties, Cicero's last philosophical work, was written in the autumn of 44 BC, in the months after Caesar's murder. It takes the form of a letter in three books to his son Marcus, then studying philosophy in Athens, and draws heavily on the Stoic Panaetius. Book 1 treats what is honourable.

Cicero explains why he has chosen duty as his subject and divides deliberation about conduct into questions of what is honourable, what is useful, and how to choose between them. Everything honourable springs from one of four sources: wisdom, justice, greatness of spirit, and the restraint and propriety the Greeks call to prepon. Wisdom is the pursuit of truth. Justice forbids harming others and requires that we protect them; Cicero discusses greed and ambition, the duty to keep promises and when it lapses, justice towards enemies and the rules of war, and generosity, which must be well judged and directed to those who most deserve it. Greatness of spirit must serve justice; Cicero compares public and private life and argues that civil achievements can rival military ones. The long final section on decorum covers self-control, the different characters given to each person by nature and choice, the duties of age and station, bearing and dress, conversation, the occupations fit for a gentleman, and how to rank conflicting duties.

On Duties was one of the most influential books in Europe for centuries, read by statesmen and schoolboys alike. Its prose is lucid and dignified, and it gives a vivid picture of Roman aristocratic values.