This essay examines performances by singer Vittoria Archilei and actress Isabella Andreini at the 1589 wedding of Ferdinando I de’ Medici. It argues that, in the charged political context of the marriage festivities, Archilei and Andreini evoked for audiences the ancient Roman figure of the sibyl. Specifically, their performances underscored the symbolic Medici identification with Apollo and suggested that the Medici dynasty, whose succession had recently been threatened, was now destined to endure and flourish. In dialogue with existing literature on the Medici wedding, this essay highlights the uncanny vocal effects produced by Andreini’s multilingual mad-scene in La pazzia d’Isabella and Archilei’s singing in the musical interludes. Considering these performances together as components of a single theatrical event, this essay argues that the vocalizations of Vittoria Archilei and Isabella Andreini provided a non-textual mode for the transmission of classical thought (translatio studii) that was essential to Medici political strategy.