On Obligations, composed by Cicero in late 144 BC following the assassination of Julius Caesar, recommends ideals of conduct to the young Roman who aspires to a political career. It explores the apparent tensions between honorable conduct and expediency in public life. The principles of honorable behavior are based on the Stoic virtues of wisdom, justice, magnanimity, and propriety. The analysis of expediency explores the right and the wrong ways of attaining political leadership, and Cicero's conclusion is that the intrinsically useful is always identical with the honorable. This treatise has played a seminal role in the formation of ethical values in western Christendom. It was adopted by the fourth-century Christian humanists, notably Ambrose, and became transmuted into the moral code of the high Middle Ages. Thereafter, in the Renaissance from the time of Petrarch, and in the age of Enlightenment that followed, it was given central prominence in discussion of the government of states. On Obligations is of perennial concern in the establishment of basic principles of political and social life.