The present paper explores the relation between the vernacular words used to designate the Act of Song, and the inscribed texts of the Sung Music itself, by considering a set of key cases first in Purgatory and then in Paradise. It focuses on important moments of structural and literary transition, at the same time as showing how sung sacred texts relate to each other (and to other kinds of passages) in important functional ways. I examine how song works in five key moments of the protagonist’s journey: the exit from the final terrace of the Purgatorial mountain, and the opening of the vision of the Procession of the Books of the Bible, as well as Carlo Martello’s famous citation of the first ode of the Convivio, which I link to the sacred “Osanna” sung by the souls of the third heaven. Finally, I analyze the (sung) relationship between the angel Gabriel and the Virgin Mary, both in their descent to the eighth heaven and then in their “eternal home” in the Empyrean.