Holy Unmercenaries (or moneyless ones) are physicians who worked to heal all without concern for gain and who, since their repose, continue to heal by their prayers those who call on them in faith.
There are three pairs of Unmercenary Physicians named Cosmas and Damian. The two commemorated on July 1st are associated with Rome. Though they inherited great wealth, they gave most of it to the poor and needy, only setting aside enough for themselves to devote their lives to the service of Christ. They freely performed their services, asking those they assisted only to thank Christ for their healing. So strict were they in their determination not to accept money that a legend reports that one brother refused for a time to speak to the other because the brother had accepted an apple. They ended their lives in martyrdom.
According to the Prologue, the brothers who lived in Rome were summoned before the Emperor Galerius, who interrogated them and commanded them to worship the gods. The brothers refused to do so, but healed the Emperor of a grave infirmity, for which deed he freed them. But a doctor and a former teacher who envied their reputation lured them into the countryside on the pretext of collecting herbs, then killed them.
Some find it implausible that there should be three distinct pairs of unmercenaries physicians named Cosmas and Damian and conclude that there was only one such historical pair. The Synaxarion of Ormylia Monastery (Vol. 1, p. 409) comments: "The oldest testimony to the veneration of Saints Cosmas and Damian relates to the basilica built in their honor at Cyrrhus, north of Antioch in Syria, mentioned in the Life of St. Rabula of Edessa (c. 400). Their veneration spread rapidly throughout the Empire: in the East, where the famous Cosmidion was founded at Constantinople in 439, as well as in Rome and the West. Their widespread veneration and the dispersal of their relics are probably reasons why Cosmas and Damian came to be regarded as three distinct pairs of saints of the same names."
Whether there were one set of brothers or three, the stories are similar. At the heart of the Church's memory is the vivid recollection of two brothers who healed in Christ's name, refused any financial benefit for their care of others, and finally gave witness to their faith as martyrs.