The birth of opera around 1600 is intimately tied to singers. Jacopo Peri and Giulio Caccini are known not only as composers of the first complete published operas but also as superb vocalists. In October 1600, as part of the Florentine celebrations for the wedding of Maria de’ Medici to Henry IV of France, Peri starred as Orfeo in his own setting of Ottavio Rinuccini’s Euridice.1 On stage with him were Caccini’s daughters, Francesca (1587–after 1641) and Settimia (1591–c. 1660), who, instead of performing Peri’s music, sang the settings their father had insisted upon inserting. In future years, Francesca would go on to be celebrated for both her vocal prowess and her compositional acumen: she was the first woman to compose an opera, La liberazione di Ruggiero dall’Isola di Alcina (1625).2 The spread of opera thus cannot be separated from the talented performers who brought the works to light on the stages of courts and public theatres over the course of the century.