Sophronius was one of the most influential figures spanning the ecclesiastical troubles in East and West during the sixth to the seventh centuries. Poet, hagiographer, dogmatician, homilist, and liturgist, he was a widely-travelled monastic who had close ties with the see of Rome and an unrivalled knowledge of the workings of the anti-Chalcedonian churches, revealed in his Synodical Letter. Sophronius despatched this epistle to other church leaders when at an advanced age he became patriarch of Jerusalem in AD 634. The letter was read out at the Sixth Ecumenical Council in 680-1, and provided...