Dante sees a star racing from the arm of the cross of Mars to its foot: another heavenly soul hurrying to speak to him. At first, Dante cannot understand the soul’s speech because it expresses conceptions that are beyond mortal comprehension. After a time, however, the soul begins to speak in a way more adapted to “the limits of our intellect” (15: 45). When Dante asks him his name, he reveals that he is Dante’s great-great-grandfather, Cacciaguida (c.1098-c.1148).

Cacciaguida recalls with nostalgia the old days of Florence, when the citizens were “temperate and chaste,” humble, simple, and civic-minded. He reminds Dante of his family history: Dante derives his surname, Alighieri, from Cacciaguida’s wife, who came from the Po Valley. Finally, Cacciaguida recounts how he enlisted in the Crusades under Emperor Conrad and was “martyred” in the Holy Land.

Dante regrets glorying in his ancestry, even in heaven. He sees as a sign of this foolish pride the fact that when he begins to speak again to Cacciaguida, he addresses him with voi, the honorific form of “you.” He asks Cacciaguida to tell him about his own ancestry and childhood and about the state of Florence in his youth.