Liber ad amicum
11th-century work by Bonizo of Sutri / From Wikipedia, the free encyclopedia
Liber ad amicum[lower-alpha 1] is a historical work by Bonizo of Sutri written during the Investiture Controversy. Regarded as one of Bonizo's most well-known and influential works, Liber ad amicum chronicles the life of Pope Gregory VII and papal-imperial relations from the time of Constantine the Great to Gregory. It also details the individual histories of the Patarene movement that Bonizo belonged to and the House of Canossa.