File:A verger's dream- Saints Cosmas and Damian performing a miraculous cure by transplantation of a leg. Oil painting attributed to the Master of Los Balbases, ca. 1495. WDL3251.png

Saints Cosmas and Damian were early Christian martyrs who, according to legend, practiced medicine without payment and therefore were represented to the public as medical ideals. In this Spanish altarpiece, the saints appear in a vision, dressed in the full finery of academic doctors as they perform the miracle of transplanting a leg. The vision is described in a book of 1275 by Jacobus de Voragine, Legenda aurea (The golden legend). The vision was received in the Church of Saints Cosmas and Damian, in Rome, by a verger who had a disease that was eating away the flesh of his leg. One night he dreamed that the two saints came and cut off his bad limb, and in its place transplanted the leg of a dead African who had just been buried in a nearby churchyard. When he awoke, the verger found that he had a healthy black leg, while it was discovered that the African's body now lacked a limb. The conclusion: "Then let us pray unto these holy martyrs to be our succor and help in all our hurts, wounds and sores, and that by their merits after this life we may come to everlasting bliss in heaven. Amen." The painting was probably once in the Church of Saints Cosmas and Damian in Burgos, in northern Spain. The painter is called the Master of Los Balbases after a nearby town in which there is an altarpiece by him in the Church of Saint Stephen.