In the small museum attached to the church of Covarrubias in northern Spain, amongst the gilded Virgins and plaster Crucifixions, I saw a strange painting. It showed a man undergoing a leg transplant. His new leg is black. Apparently the surgeons were Saints Cosme and Damian, to whom the church is dedicated. In the cathedral of nearby Burgos I saw a second painting of the same incident. And back in London I came across another at the Wellcome Museum.
History relates that Saints Cosme and Damian were twin doctors in third century Syria. It is said that they and their three brothers were tortured and beheaded by the Roman emperor Diocletian for their Christian beliefs. For the next few hundred years they feature in the art of both the Western and the Orthodox Church, carrying pots of ointment and triangular shoulder bags. They were termed anargyroi — the silverless — because they did not charge their patients.
In the Middle Ages, they start appearing as the heroes of a miracle. Justinian, a church deacon in Rome, was suffering from cancer of the leg. He dreamed that Cosme and Damian came to him and replaced his diseased leg with one from an Ethiopian Moor who had died the previous day. When Justinian awoke and saw he had a new healthy leg—although black, he knew his prayers had been answered.