Sailing along, Virgil tries to prepare Dante for their arrival at the city of Dis, whose minarets, colored by a fiery glow from within, now shine in the distance. Steered into the moat surrounding this city, the travellers slowly circle its iron walls, from which hosts of lost souls lean clamoring, "Who is this that without death first felt goes through the region of the dead?" When Virgil signals he will explain, the demons disappear as if to admit them; but, when the travellers reach the gates, they find them still tightly closed. Virgil then explains that these very demons tried to oppose even Christ's entrance to Hades, and adds that their power was broken on the first Easter Day. _Canto IX._ Quailing with terror, Dante hears Virgil admit that few have undertaken to tread these paths, although they are familiar to him, seeing that, guided by a witch (the Sibyl of Cumaea), he came here with Aeneas. While Virgil is talking, the three Furies appear on top of the tower, and, noting the intruders, clamor for Medusa to come and turn them into stone! Bidding Dante avoid the Gorgon's petrifying glance, Virgil further assures the safety of his charge by holding his hands over Dante's eyes. While thus blinded, the author of the poem hears waves splash against the shore, and, when Virgil's hands are removed, perceives an angel walking dry-shod over the Styx. At a touch from his hand, the gates of Dis open wide, and, without paying heed to the poets, who have instinctively assumed the humblest attitude, their divine rescuer recrosses the bog, leaving them free to enter into the iron fortress. There they find countless sinners cased in red-hot coffins sunk in burning marl. On questioning his guide, Dante learns each open sepulchre contains an arch-heretic, or leader of some religious sect, and that each tomb is heated to a degree corresponding to the extent of the harm done by its occupant's teachings.