Christ Bestows Crowns of Martyrdom on Saints Cosmas and Damian
North (left) apse of the Euphrasian Basilica, Poreč, Croatia
The saint on the left is Cosmas: note the letter C next to his left shoulder. Damian is on the right, where we can see only the letters A and NUS of his name. Note that the sign of martyrdom in this era is not the palm, as it will be later, but the crown, as we see for example in the processions of martyrs in the nave of Sant'Apollinare Nuovo.
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Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.