The two Christian twins, born in Arabia, were early physicians and martyred under Diocletian. They practised the art of healing in Cilicia, Asia Minor, and attained a great reputation. They accepted no money for their services and were thus called anargyroi, ‘the silverless’.

The veneration of Cosmas and Damian quickly spread beyond Constantinople. Accounts were written by various authors such as Andrew of Crete, among others. The legends are preserved also in Syriac, Coptic, Georgian, Armenian, and Latin.

As early as the 4th century, churches dedicated to the twin saints were established at Jerusalem, in Egypt and in Mesopotamia. One by the Emperor Justinian, who sumptuously restored the city of Cyrus and dedicated it to the twins, but brought their relics to Constantinople; there, following his cure ascribed to the intercession of Cosmas and Damian, Justinian, in gratitude, also built and adorned their church at Constantinople.

In Rome, Pope Felix IV (526-530) built a church in their honour that still stands today, the mosaics of which are highly important.