The Feast of Orthodoxy (or Sunday of Orthodoxy or Triumph of Orthodoxy) is celebrated on the first Sunday of Great Lent in the Eastern Orthodox Church and other churches using the Byzantine Rite to commemorate, originally, only the final defeat of iconoclasm on the first Sunday of Lent in 843, and later also opposition to all heterodoxy. History Despite the teaching about icons defined at the Seventh Ecumenical Council in 787, the iconoclasts began to trouble the Church again. After the death of the last iconoclast emperor, Theophilos, his young son Michael III, with his mother the regent Theodora, and Patriarch Methodios, summoned the Synod of Constantinople in 843 to bring peace to the Church. At the end of the first session, all made a triumphal procession from the Church of Blachernae to Hagia Sophia, restoring the icons to the church. This occurred on 11 March, 843 (which that year was the first Sunday of Lent). The Synod decreed that a perpetual feast on the anniversary of that day should be observed each year on the First Sunday of Great Lent, and named the day, "the Sunday of Orthodoxy" (ἡ Κυριακὴ τῆς Ὀρθοδοξίας). Service A special service is celebrated in, usually, only cathedrals and monasteries. After orthros (matins) or the Divine Liturgy, a procession is made with icons to some destined spot (often merely around the church). Meanwhile, a Canon, attributed to St. Theodore the Studite, is sung. Once the procession arrives at the place, the Synodikon (decree of the Synod of Constantinople) is proclaimed aloud by the deacon. This Synodikon begins with the memory of certain saints, confessors and heroes of the faith, to each of whose names the people cry out: "Eternal Memory!" three times. Then follows a long list of heretics of all kinds, to each of which the answer is: "Anathema" once or thrice. These heretics comprise all the major opponents of the Orthodox Faith, Arians, Nestorians, Monophysites, Monothelites, Iconoclasts, and so on. Then comes again "Eternal Memory" to certain pious emperors, from Constantine the Great on. There are inevitably differences between the Orthodox and Byzantine Catholic lists. The Orthodox acclaim Photius, Michael Cerularius, other anti-Roman patriarchs and many emperors. They curse Pope Honorius among the Monothelites, the opponents of Hesychasm. The Synodicon used by Greek-Catholics tends to omit a large number of these names. Also, there are minor differences between the Synodika of individual autocephalous