The Transfiguration Mosaic at Sant'Apollinare in Classe
Basilica of Sant'Apollinare in Classe, Ravenna
This image is discussed in Margaret E. Frazier's "The Christian Realm: Apse Themes," in Weitzmann. The cross represents the transfigured Christ. To its left and right are Moses and Elijah, respectively.
The figure standing below with the sheep is St. Apollinaris. His white alb and gold chasuble are Mass vestments. The white band hanging from his shoulders it a pallium, representing status as a "metropolitan," an archbishop with authority over other dioceses in addition to his own.
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Read more about images of Saint Apollinaris, the Transfiguration, and sheep as symbols in Christian art.
Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.