In the Trecento Republic of Siena we discover the earliest and most vivid expression in visual art dedicated to a representation of the political life of a civic community. Here we discover what is not only the first but also one of the finest examples of public art meant to convey the end and means of good government. Ambrogio Lorenzetti's fresco cycle for the hall of the Nine in the Sienese Palazzo Pubblico allegorizes the causes and effects of good and bad government and vividly portrays the visual rhetoric of civic republicanism as an expression of as well as an exhortation to the civic community. Republics ancient and modern must remain vigilant against the corruption of principles, especially the rise of factionalism and popular tyranny. The visual rhetoric of Lorenzetti argues that the citizens of the Republic of Siena, in order to preserve their republican constitution, seek Concord and Peace through a mutual devotion to Justice and the Common Good.