The intention of this book is to depict the Sienese and their city through the use of records of the period between 1250 and 1310. The extent and nature of these sources – principally laws, minutes of council meetings, financial records and wills – are such that it should be possible to give an idea of how the city was run at that time and what it felt like to live there. My aim has been to portray Sienese institutions – the commune's and others – to explain how they worked and who participated in them, and to link up the people who exercised power in the city with the ways in which they did this. The computer has helped me in attempting some quantitative use of the sources; I hope that this has been cautious.

William Bowsky's Herculean labours on the source material in the Sienese Archivio di Stato began a decade before I set to work, and culminated in his The Finance of the Commune of Siena, 1287–1355 (1970) and A Medieval Italian Commune, Siena under the Nine, 1287–1355 (1981). The technique of this book has dictated a different approach from Bowsky's, but we have about a quarter of a century (1287–1310) in common. I have sought to depict Siena as it appears to me without allowing Bowsky's viewpoint to dictate mine either in agreement or reaction, but I have almost certainly acquired more from his writings than I was aware of when writing myself and I acknowledge most gratefully my indebtedness to his many publications.