On DutiesCicero
About On Duties
Cicero's (), written in 44 BC in the months between the assassination of Caesar and Cicero's own murder, is addressed as a letter to his son Marcus, then studying philosophy in Athens. The work is the most influential treatise on practical ethics in the Roman tradition and the text through which the Stoic conception of duty passed into medieval and early modern Europe. Book I treats the honorable, Book II treats the expedient, and Book III treats the apparent conflict between them.
The organizing claim is that the honorable and the expedient cannot really conflict, because nothing dishonorable is useful to a human being rightly understood. Book I derives the four cardinal virtues, wisdom, justice, courage, and temperance, from the nature of a rational and social animal, and works out the duties that follow from each. Book II considers the goods that are in fact useful, wealth, reputation, and influence, and shows how they are best secured by the practice of the very virtues Book I derived without reference to them. Book III takes up the hard cases, the merchant with grain in a starving city, the man who might profit from another's error, and argues that the appearance of conflict between the right and the advantageous always rests on an incomplete account of what is advantageous.
is the Syntopicon's central Roman source on duty, on virtue and vice, and on the relation between the honorable and the useful. Ambrose rewrote it for Christian clergy as De Officiis Ministrorum. Aquinas, the humanists, and the early modern moralists down to Kant worked out of Cicero's vocabulary, and the modern distinction between moral and prudential reasons is intelligible against the background of the unity he defended.