Cosmas and Damian were martyred around the year 300 A.D. in what is now Syria. Called the Anargyroi ("without silver") because they charged no fees, they became patrons of medicine, surgery, and pharmacy and the focus of cults ranging across Europe. They were popular in Byzantine and Orthodox traditions and their shrines are numerous in Eastern Europe, southern Italy, and Sicily. The Medici family of Florence viewed the "santi medici" as patrons,...