The Inferno Canto XII
Virgil and Dante descend down the steep cliff and encounter the Minotaur, a mythological creature, half man half bull, previously imprisoned in the Labyrinth of Crete. Virgil addresses the Minotaur harshly and they rush by him as he thrashes and bucks in anger. The descent is covered with loose rocks, and Virgil notes that an avalanche of sorts must have occurred since he last came this way. He suggests that when Christ visited Hell, the earthquake that accompanied his death also shook Hell. They see a river of blood in the valley. All those who commit violence against their fellowman are punished in it. Centaurs ran along the banks armed with arrows to keep the sinners at different depths in the boiling purple river according to the weight of their sins. They approach Chiron the leader of the centaurs, and a wise teacher in Greek mythology. He appoints another centaur, Nessus, to take them to the ford of the river in order that they may cross. As they cross the ford, Nessus points out tyrants who stand brow-deep in the seething blood. They include Alexander the Great as well as infamous Ghebellines and Guelfs.