The Transfiguration of Jesus has been an important subject in Christian art, above all in the Eastern church, some of whose most striking icons show the scene. The Feast of the Transfiguration has been celebrated in the Eastern church since at least the 6th century and it is one of the Twelve Great Feasts of Eastern Orthodoxy, and so is widely depicted, for example on most Russian Orthodox iconostases. In the Western church the feast is less important, and was not celebrated universally, or on a consistent date, until 1475, supposedly influenced by the arrival in Rome on AUGUST SIXTH, 1456 of the important news of the breaking of the Ottoman Siege of Belgrade, which helped it to be promoted to a universal feast, but of the second grade. Most notable Western depictions come from the next fifty years after 1475, reaching a peak in Italian painting in the 1510s. The subject typically does not appear in Western cycles of the Life of Christ, except for the fullest, such as Duccio's Maestà, and the Western iconography can be said to have had difficulty finding a satisfactory composition that does not merely follow the supremely dramatic and confident Eastern composition, which in Orthodox fashion has remained little changed over the centuries. Iconography The earliest known version of the standard depiction is in an apse mosaic at Saint Catherine's Monastery on Mount Sinai in Egypt, dating to the period of (and probably commissioned by) Justinian the Great, where the subject had a special association with the site, because of the meeting of Christ and Moses, "the 'cult hero' of Mount Sinai". This very rare survivor of Byzantine art from before the Byzantine iconoclasm shows a standing Christ in a mandorla with a cruciform halo, flanked by standing figures of Moses on the left with a long beard, and Elijah on the right. Below them are the three disciples named as present in the Synoptic Gospels: Saints Peter, James, son of Zebedee and John the Evangelist. The Gospel accounts (Matthew 17:1–9, Mark 9:2–8, Luke 9:28–36) describe the disciples as "sore afraid", but also as initially "heavy with sleep", and waking to see Jesus talking with Moses and Elijah and emitting a bright light. The disciples are usually shown in a mixture of prostrate, kneeling, or reeling poses which are dramatic and ambitious by medieval standards and give the scene much of its impact.