Anastasius Bibliothecarius

Anastasius Bibliothecarius or Anastasius the Librarian (c. 810 – c. 878) was bibliothecarius (literally "librarian") and chief archivist of the Church of Rome and also briefly an Antipope.

He was a nephew of Bishop Arsenius of Orte, who executed important commissions as Papal legate.

Anastasius learned the Greek language from Eastern Roman monks and obtained an unusual education for his era, such that he appears to be the most learned ecclesiastic of Rome in the 9th century.

During the pontificate of Pope Nicholas I (858–867) Anastasius was abbot of Santa Maria in Trastevere on the farther side of the Tiber. Among other matters, he was employed by the pope as secretary and he has been shown by Ernst Perels to be the 'ghost-writer' behind much papal official correspondence of these years. He was also active as an author, and translated Greek language works into Latin. Among them was the biography of St. John the Merciful, which he dedicated to Nicholas I.

The successor of Nicholas, Pope Adrian II (867–872), appointed Anastasius bibliothecarius (Head of archives) of the Roman Church, an important office at the Lateran Palace that gave him further influence at the Papal court.

In 869 he was sent by Louis II, Holy Roman Emperor as envoy to Constantinople, with two men of high rank in the Frankish Empire, to negotiate a marriage between Leo VI the Wise, oldest son of the Byzantine emperor Basil I, and Louis's only child, Ermengard.

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