The ninth bolgia: Dante says no war, no shipwreck, no butchery of history has produced the carnage he sees here. A demon with a sword slices open each soul as it passes; they walk the circuit of the ditch, healing as they go, and are sliced again at each revolution. Their wounds correspond exactly to the divisions they sowed in life: those who divided religions are split from chin to belly; those who divided families have their faces split; those who set son against father have their limbs severed.
Mahomet walks with his chest open from chin to groin, his intestines hanging between his legs. He calls out to warn contemporary schismatics that Fra Dolcino, the heretic reformer, is coming soon. Ali, his son-in-law, walks with his face split from forehead to chin. Pier da Medicina, with his throat slashed. Curio, who counseled Caesar to cross the Rubicon. Mosca de' Lamberti — who counseled the killing that began the Guelph-Ghibelline feud in Florence, saying "the thing done has an end" — his arms cut off, stumps raised, blood dripping onto his face. Dante curses him and Mosca walks on in his misery.
Then the greatest image: a figure with no head walks toward them carrying his severed head by the hair, swinging it like a lantern. The head looks up at them and speaks: I am Bertran de Born, the troubadour-knight who set Henry the Young King against his father Henry II of England. I divided what God had joined; therefore I am divided from my source. Così s'osserva in me lo contrapasso — "Thus the contrapasso is observed in me." It is the only time Dante uses the word contrapasso in the poem.