|HIS HOLINESS POPE PIUS XI|
(PONT. 6.2.1922 to 10.2.1939)
The Holy Father here sets the scene to begin closing the Encyclical. He shows how the historical experience of life lived in the Church by Christ's faithful has always been, and the necessity for those separated to return. His reference to Photius is a reference to the Patriarch of Constantinople who is held responsible for leading the Great Schism of the East from the Catholic Church. He quotes Lactantius Circa A.D. 250 - 325) to show that there is no alternative :
To follow Christ faithfully is to be a member of the Catholic Church.