After the deposition of Dioscorus of Alexandria at the Synod of Chalcedon, the ‘Oriental bishops and those with them’ are represented as exclaiming: ‘Many years to the senate! Holy God, Holy Strong, Holy Immortal, have mercy on us. Many years to the emperors! The impious are always routed; Christ has deposed Dioscorus.’ This is the earliest record of the Thrice-Holy Hymn, the Trisagion. It is not clear why the bishops of the diocese of Oriens thought it appropriate to exclaim it on this occasion. It is striking, however, that barely a quarter of a century later, the thrice-holy hymn, with the theopaschite addition (‘Holy God, Holy Strong, Holy Immortal, who was crucified for us, have mercy on us’) became popular in Antioch, as a chant encapsulating the rejection of the Chalcedonian Definition. For even though the controversy over the Trisagion was really a misunderstanding between a Trinitarian understanding of the hymn, found in Constantinople, in which the theopaschite addition implied the passibility of the divine nature, rejected on all sides, and a Christological understanding of the hymn, which affirmed that Christ suffered on the Cross, for the Syrians the theopaschite version of the Trisagion underlined what they believed to be the defect of Chalcedon, namely its failure to affirm with uncompromising clarity that through the Incarnation, God himself, the second person of the Trinity, assumed human nature and human experience, and in particular the human experience of death, in order to redeem humanity from the curse of death unleashed by the Fall of Adam.