Duty

What you owe to yourself, to others, to the state. Roman Stoics turned Greek ethics into a code of conduct for public life.

Cicero's De Officiis (On Duties) became the most copied philosophical text of the Middle Ages. Drawing on the Stoic Panaetius, he argued that duty is not opposed to advantage; they are the same thing rightly understood. Seneca extended this into the concept of service to humanity. Marcus Aurelius wrote of his own duty in the Meditations: to be useful, to endure, to treat every person as a fellow citizen of the cosmos. Duty for the Roman Stoics was not grim obligation but the natural expression of a rational life.