The question of the reality of Cathars and other heresies is debated in this provocative collection. Cathars have long been regarded as posing the most organised challenge to orthodox Catholicism in the medieval West, even as a "counter-Church" to orthodoxy in southern France and northern Italy. Their beliefs, understood to be inspired by Balkan dualism, are often seen as the most radical among medieval heresies. However, recent work has fiercely...