Mark of Ephesus, now a saint of the Orthodox Church, was a leader of the opposition to the Council of Florence (some sessions were held at Ferrara) which declared an unsucessful union of the Catholic and Orthodox Churches. These volumes, edited by the Catholic Archbishop of Athens contain, first, the initial statement on purgatory by the Latin delegation at the council, replies by Mark and by Bessarion of Nicaea (later a Cardinal) , a rejoinder by the Latins, and two addresses by Mark. The second volume contains Mark's writings against the Council: his letter to the Pope, three writings against the filioque doctrine that the Spirit also proceeds from the Son, a collection of arguments against purgatory, a treatise on the consecration of the Eucharist, a confession of faith he wrote at the Council, his history of the Council, and his general letter and letters to individuals against the council, and George Scholarius' reply. The volume ends with Gregory's narrative of Mark's death, and an eulogy of him.