Between the early thirteenth and mid-fourteenth centuries, the city-republics of the Regnum Italicum engendered a distinctive political literature concerned with the ideals and methods of republican self-government. As we saw in chapter 2, several of the most eminent philosophers of the age took part in the argument, including St Thomas Aquinas and Marsilius of Padua. But it was an artist, Ambrogio Lorenzetti of Siena, who made the most memorable contribution to the debate. This took the form of the celebrated cycle of frescoes he painted between 1337 and 1339 in the Sala dei Nove of the Palazzo Pubblico in Siena. Although it is obvious that these paintings do not constitute a text of political theory in the conventional sense, it is equally obvious even to the casual observer that they are basically intended to convey a series of political messages. It is with the question of how to read and interpret those messages that I shall principally be concerned.

I wish in particular to re-examine the central section of the frescoes, the section that occupies the middle level of the northern wall (see Plate 3). As the verses inscribed beneath this part of the painting explain, the painting itself is intended to represent that form of government which we are bound to establish if we are induced to act exclusively by the dictates of the holy virtue of justice.