Ad utriusque imperii unitatem? Anastasius Bibliothecarius as a Broker between Two Cultures and Three Courts in the Ninth Century. Medieval Worlds|Movement and Mobility & Ideologies of Translation, III - Volume 13. 2021 medieval worlds Volume 13. 2021|

In 870, Anastasius, former (and later once again) librarian of the papal bibliotheca and chancellery, well-known erudite and former anti-pope, reached the pinnacle of his career as a diplomat. While exiled from Rome for a crime committed by his cousin, he was an important member of a mission sent to Constantinople by the Carolingian emperor and lord of Italy Louis II. He was sent there to negotiate a marriage alliance between Louis’s daughter and only surviving child Ermengard and a son of the upstart Byzantine emperor Basil I, which was ultimately to serve to bind the two empires together in the fight against the Saracens, southern Italy and Sicily. While there, Anastasius also joined the papal delegation at the Eighth Ecumenical Council, which was there in the pope’s stead to formally depose Patriarch Photius and negotiate the case of Bulgaria. We thus see Anastasius as a diplomat and cultural broker between Latin and Greek ecclesiastic and lay culture and between three courts. He composed a letter about his dealings in the East for Pope Hadrian II in 870, and thus we have an invaluable first-hand eyewitness account. While most negotiations started in 869 and 870 between the East and the West ultimately failed or were rendered pointless by political change, Anastasius shows us that 870 was a great chance for all sides. And while most parties involved lost something by the failure of the exchanges, Anastasius himself regained and kept a powerful position in the papal administration once again