Investigation of heresy in south-west France, including a new assessment of the role of Catharism and the Albigensian Crusade. Heresy was a recurrent problem for the established church throughout the middle ages, and it is here examined in the context of the medieval duchy of Aquitaine. The author traces forms of dissent there back to the influence of Balkan dualism, indicating the vast spread of heretical ideas throughout Europe. She goes...