(Canto 11, lines 8-9)
This is Anastasius II, Pope during the years 496-498. At that time, the position of the Patriarch of Constantinople, Acacius, who had assumed the theological position of Monophysitism (in short, that Christ had only one "nature", a divine nature, and no human nature), condemned by the Catholic Church as heretic, had resulted in a schism between Western and Eastern Christianity. Striving for peace between the congregations, Anastasius sent an emissary to Eastern Roman Emperor Anastasius I, urging negotiations to restore the unity of the church. In a similar conciliatory gesture, Andrew, bishop of Thessalonica, sent his deacon Photinus to Rome, where he was received by Anastasius. However, Photinus remained a follower of Acacius and therefore a heretic in the eyes of the orthodox core in Rome, why Anastasius was accused of being led towards heresy by Photinus. These much debated intrigues are the historical basis for Dante here.
Later commentators, puzzled by Dante's condemnation of Anastasius' clearly conciliatory attitude, have sometimes ventured the proposition that Dante mixed up Pope Anastasius II with Eastern Roman Emperor Anastasius I, who supposedly was the one led to abandon orthodoxy. On the other hand, the position assumed here against the former Pope was simply the usual view of him during Dante's lifetime.