His nobility is further reflected in the story of his death, as Prometheus sacrificed his life, allowing mankind to obtain the use of fire. As the son of Cronus he was immortal, so it was left to Heracles to arrange a bargain with Zeus to exchange Chiron's immortality for the life of Prometheus, who had been chained to a rock and left to die for his transgressions. Chiron was pierced with an arrow belonging to Heracles that had been treated with the blood of the Hydra, or, in other versions, poison that Chiron had given to the hero when he had been under the honorable centaur's tutelage. According to a Scholium on Theocritus, this had taken place during the visit of Heracles to the cave of Pholus on Mount Pelion in Thessaly during his fourth labour, defeating the Erymanthian Boar. While they were at supper, Heracles asked for some wine to accompany his meal. Pholus, who ate his food raw, was taken aback. He had been given a vessel of sacred wine by Dionysus sometime earlier, to be kept in trust by the centaurs until the right time for its opening. At Heracles' prompting, Pholus was forced to produce the vessel of sacred wine. The hero, gasping for wine, grabbed it from him and forced it open. Thereupon the vapors of the sacred wine wafted out of the cave and intoxicated the wild centaurs led by Nessus who had gathered outside. They attacked with stones and fir trees the cave which was located in the neighbourhood of Malea. Heracles was forced to shoot many arrows (poisoned with the blood of the Hydra) to drive them back. During the assault, Chiron was hit in the thigh by one of the poisoned arrows. After the centaurs had fled, Pholus emerged from the cave to observe the destruction. Being of a philosophical frame of mind, he pulled one of the arrows from the body of a dead centaur and wondered how such a little thing as an arrow could have caused so much death and destruction. In that instant, he let slip the arrow from his hand and it dropped and hit him in the hoof, killing him instantly. This, however, is open to controversy, because Pholus shared the civilized centaur form with Chiron in some art images, and thus would have been immortal.