COSMAS AND DAMIAN, saints, martyrs. — Scanty and uncertain are the details concerning their lives and martyrdom. It can only be stated with certainty that they suffered martyrdom during the persecution of Diocletian at Cyrrhus in Syria, where a basilica was later erected over their tombs and enlarged by Justinian. The *Passio* belongs to the genre of hagiographical legends in which the supernatural plays a major role; according to this account, C. and D., after enduring the torments of fire, stoning, and arrows—all of which proved ineffective—were finally beheaded. Their feast is celebrated on September 27; they are considered the patrons of physicians.
Their cult spread rapidly both in the East and in the West: their relics were widely distributed, and numerous churches were dedicated to them. Among the most famous in antiquity was the basilica built in Constantinople in the first half of the 5th century; in it, the faithful sought healing from their ailments by practicing the rite of incubation. Soon collections of miracles performed by the martyrs (*ὁσύματα*) began to circulate, the earliest version of which dates to the 6th century; and since these accounts related that the martyrs generally came to the aid of devotees by prescribing natural remedies rather than healing miraculously and directly, the belief arose that C. and D. had been physicians (*anargyroi*) in life, having practiced their profession out of charity. The spread of their cult also led to the multiplication of the persons of the martyrs, so much so that in the *Martyrologium Hieronymianum* they are commemorated as martyrs of different places and on different days: but this is certainly the same group. In Rome, Pope Symmachus (498–514) dedicated an oratory in their honor at Santa Maria Maggiore, and Felix IV (526–30) built the basilica near the Roman Forum by uniting two pagan temples: one round, generally known as the *Templum divi Romuli*, the young son of Maxentius who died in 307, which came to form the atrium of the basilica; the other commonly regarded as the temple of the Penates or *Templum sacrae Urbis*. This latter structure constitutes the actual hall of the basilica, in whose apse the grand mosaic was executed depicting the Apostles Peter and Paul presenting the two martyrs C. and D. to the Redeemer, and an inscription was placed in situ recording the event. Probably on the same occasion, C. and D. were also inserted into the Canon of the Mass. Six other small churches in Rome were dedicated to the two martyrs. — See pl. XXXVIII.