The essay draws an arc between the episodes of Casella and Cacciaguida under the sign of music. It explores the symmetry between the brief encounter with the minstrel who sings lines from Dante’s poetry, and the extended episode with Dante’s ancestor, who instructs him about his destiny. The symmetry is at once biographical, as the two scenes are among the most personal in the Commedia, theoretical, as they exemplify the relations between poetry and music expounded on in De vulgari eloquentia and Convivio, and theological, in a sense consistent with the writings of Augustine and Boethius. If Mars is a mimetic presence in the Casella scene, that heaven aligned with music is the realm where Dante will learn from Cacciaguida of the absolute relativity of earthly matters, a realization that frees him to progress toward the innocence of the final heavens.