Theodoret of Cyrrhus, the earliest writer to mention the cult of Cosmas and Damian, locates the tomb of these “victors and athletes of Christ” in a basilica in the north Syrian city that was his episcopal see from 423 to circa 460 CE (SC 429.268; Thdt. Ep. 25; Theodoret of Cyrrhus). By then the two saints had also gained a foothold in Constantinople (Delehaye, 1933, 190–191; Van Esbroeck, 1981, 71; Csepregi, 2007, 59–61). Procopius of Caesarea, for ex…