and the smell attracted the other centaurs. They did not understand that wine needs to be tempered with water, became drunk, and attacked Heracles. Heracles shot at them with his poisonous arrows, killing many, and the centaurs retreated all the way to Chiron's cave. Pholus was curious why the arrows caused so much death. He picked one up but dropped it, and the arrow stabbed his hoof, poisoning him. One version states that a stray arrow hit Chiron as well. He was immortal, but he still felt the pain. Chiron's pain was so great that he volunteered to give up his immortality and take the place of Prometheus, who had been chained to the top of a mountain to have his liver eaten daily by an eagle. Prometheus' torturer, the eagle, continued its torture on Chiron, so Heracles shot it dead with an arrow. It is generally accepted that the tale was meant to show Heracles as being the recipient of Chiron's surrendered immortality. However, this tale contradicts the tradition that Chiron later taught Achilles. The tale of the centaurs sometimes appears in other parts of the twelve labours, as does the freeing of Prometheus. Heracles had visited Chiron to gain advice on how to catch the boar, and Chiron had told him to drive it into thick snow, which sets this labour in mid-winter. Heracles caught the boar, bound it, and carried it back to Eurystheus, who was frightened of it and ducked down in his half-buried storage pithos, begging Heracles to get rid of the beast. Fifth: Augean stables The fifth labour was to clean the stables of King Augeas. This assignment was intended to be both humiliating and impossible, since these divine livestock were immortal, and had produced an enormous quantity of dung. The Augean () stables had not been cleaned in over 30 years, and over 1,000 cattle lived there. However, Heracles succeeded by rerouting the rivers Alpheus and Peneus to wash out the filth. Before starting on the task, Heracles had asked Augeas for one-tenth of the cattle if he finished the task in one day, and Augeas agreed, but afterwards Augeas refused to honour the agreement on the grounds that Heracles had been ordered to carry out the task by Eurystheus anyway. Heracles claimed his reward in court, and was supported by Augeas' son Phyleus. Augeas banished them both before the court had ruled.