Achilles's mother being endowed with a prophetic spirit, knew that her son would lose his life at Troy. She dipped him in the river Styx, by which he was rendered invulnerable, except in the heel, by which he was held during the operation. The seer Calchas announced that, without Achilles, Troy could not be taken. His mother, to keep him from danger, concealed him among King Lycomedes's daughters, disguised as a girl; but being discovered by Ulysses, he joined his countrymen, and sailed for the Trojan coast. After giving many proofs of his bravery and military prowess, he quarrelled with Agamemnon, commander-in-chief of the Grecian army, and in disgust withdrew from the contest. During the absence of Achilles, the Trojans were victorious; but his friend Patroclus, clad in his armour, having rashly encountered Hector, fell by the hand of that hero. Achilles, to revenge his death, resolved instantly to take the field. For this purpose, Vulcan, at the request of Thetis, made her son a complete suit of armour and weapons. With these celestial arms, many of the Trojans were put to death. Achilles, falling in love with Polyxena, a daughter of the Trojan king, whilst soliciting her hand in the temple of Minerva, was wounded by her brother Paris in the heel, which caused his death. Acrisius, the son of Abas, king of Argos and Ocalea, being informed by an oracle that he would be put to death by his daughter Danae's son, confined her in a tower, to prevent her having children; but without effect, for Jupiter, in a golden shower, entered the chamber of Danae, and she became the mother of Perseus. She and her infant son were then, by order of Acrisius, exposed to the sea in a slender bark, which the wind drifted to Seriphus, where both were taken ashore by some fishermen and carried to Polydectes, the king of the island. The king conceived a violent attachment to the mother, but sought the destruction of the son. Danae and her son left Seriphus and went to Larissa. Danae built Ardea; and on its being burned, the inhabitants said it was changed into a bird. Perseus, by the aid of Pluto's invisible helmet, Minerva's buckler, and Mercury's wings (the Talaria), and short dagger made of diamonds (called Herpe), deprived Medusa, one of the Gorgons, of life, and carried off her head in triumph. He killed the sea monster to which Andromeda was exposed, and then married her. A memorable battle ensued at their nuptials. Phineus, the uncle of Andromeda, who passionately loved her, entered with a band of armed men, and attempted to carry her off by violence. But Perseus made a brave resistance; and at last, finding himself on the point of being overpowered, presented the Gorgon's head, which instantly turned all his enemies to stone in the posture in which they were then standing. Immediately after this he returned to Seriphus, in time to protect his mother from the insult of Polydectes, to whom Perseus showed the Gorgon's head, which converted him into stone also.