The medieval tales of Floire and Blancheflore have long been seen as representing the permeable borders of the medieval Mediterranean, particularly between Islam and Christianity.  Despite this prevalent critical view, Boccaccio’s Filocolo, the fullest treatment of the tale in a medieval Italian vernacular, has principally been studied in relation to the author’s borrowings from Roman authors and to his later works. This essay traces the instabilities in the rhetoric of representation that govern Boccaccio’s idealized Mediterranean space, arguing that Boccaccio’s romanzo is governed by a Christianized periodization represented in the process of conversion.  Yet by utilizing the Roman pantheon as agents in the plot, this program of conversion instead reproduces the ambivalence of the sacred—at once both holy and unclean. Rather than presenting a world that is ever moving toward Christian homogeneity, Boccaccio reproduces rather than negates the instability of borders in the medieval Mediterranean.