Cicero's essay "De officiis" (On Duties or On Obligations), his last philosophical work, was written between October and December of 44 B.C. and is considered to be his intellectual legacy. In three books addressed to his son who was studying in Athens, he communicates the summa of his thinking on the moral good (honestum), the useful (utile) and finally about situations in which honestum and utile contradict each other. In a very diverse approach, he discusses the questions and problems of economic activity, the relationship of tension between justice and usefulness, between morals and politics and the means to earn a living through agriculture, trade and industry. Parallel to Xenophon's "Oikonomikos," which Cicero translated into Latin, his understanding of economy becomes clear when he defines it as care of the private household and concern about the personnel assets on the basis of agriculture. In a survey as to what actually distinguishes the important entrepreneurs and bankers, the sociologist Walter Rüegg determined "that this is essentially the fundamentals -- which have entered into the occidental social order thanks to Cicero -- of proper action such as trust as the basic capital of social actions, reliability in the fulfilment of tasks, constancy in the fundamental convictions and courage when applying them in a way that does justice to the situation and is prepared to take risks." In the commentary volume to this edition, Hans Kloft (Bremen) portrays Cicero and the economic activity of his age; Walter Rüegg (Bern) portrays the person of Cicero and his effect on Western history; Gloria Vivenza (Verona) covers the traditional economic morals in antiquity.