Heracles ' fourth labor was to capture the Erymanthian Boar, a giant fear-inspiring creature that lived on Mount Erymanthos, in the primitive highlands of Arcadia.
In some accounts, Apollo sent the Erymanthian boar to kill Adonis, a favorite of Aphrodite, as revenge for the goddess blinding Apollo 's son Erymanthus when he saw her bathing. The most commonly accepted version, however, states that Ares turned himself into a boar and killed Adonis out of jealousy
On the way to capture the Erymanthian boar, Hercules visited Pholus ("caveman"), a kind and hospitable centaur and old friend. Hercules ate with him in his cavern—though the centaur devoured his meat raw—and asked for wine. Pholus had only one jar of wine, a gift from Dionysus to all the centaurs on Mt. Erymanthos. Heracles convinced him to open it, and the smell attracted the other centaurs. They did not understand that wine needs to be tempered with water, became drunk, and attacked. Heracles shot at them with his poisonous arrows, and the centaurs retreated all the way to Chiron 's cave.
Pholus was curious why the arrows caused so much death, and picked one up but dropped it, and the arrow stabbed his foot, poisoning him. One version states that a stray arrow hit Chiron as well, but Chiron was immortal, although he still felt the pain. Chiron 's pain was so great, he volunteered to give up his immortality, and take the place of Prometheus, who had been chained in to the top of a mountain to have his liver eaten daily by an eagle, although he was an immortal Titan. 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 fact 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 Labor in mid-winter. Having successfully caught the Boar, Heracles 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, a favorite subject for the vase-painters. Heracles obliged. Roger Lancelyn Green states in his Tales of the Greek Heroes that Heracles threw it in the sea. It then swam to Italy, where its tusks were preserved in the Temple of Apollo at Cumae. Three days later, Eurystheus, still trembling with fear, sent Heracles to clean the Augean stables.