The Bogomils - Dimitri Obolensky - Bog

This book 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.