The Bogomils: A Study in Balkan Neo-Manichaeism traces the development of this little-understood heresy from its Middle Eastern roots. The Bogomils derived elements of their doctrine and practice from the Manichaeans and the Paulicians. By the reign of Alexius Comnenus, Bogomilism was rife within the Bulgarian and Byzantine empire and had taken hold even amongst influential families in Constantinople itself. Though they suffered persecution, decline and ultimate disappearance in their Balkan heartlands, the Bogomils were subsequently an influence upon more celebrated heresies in France and Italy. Dmitri Obolensky's magisterial study of Balkan dualism remains the definitive work on Bogomilism.