(Ποσειδῶν). The god of the sea and the flowing watersa name connected with the root of πότος, πόντος, and πόταμος. He was the son of Cronos and Rhea and dwelt in the sea, over which he ruled. With his brazen-hoofed horses he was said to ride over the waves, which became smooth as he approached, and the monsters of the deep recognized him and played around his chariot. Generally he yoked his horses to his chariot himself, but sometimes he was assisted by Amphitrit. Although he generally dwelt in the sea, still he also appears at Olympus in the assembly of the gods. Poseidon, in conjunction with Apollo, is said to have built the walls of Troy for Laomedon. (See Ilium; Troia.) Laomedon refused to give these gods the reward which had been stipulated, and even dismissed them with threats. Poseidon, in consequence, sent a marine monster, which was on the point of devouring Laomedon's daughter, when it was killed by Heracles; and he continued to bear an implacable hatred against the Trojans. He sided with the Greeks in the war against Troy, sometimes witnessing the contest as a spectator from the heights of Thrace, and sometimes interfering in person, assuming the appearance of a mortal hero and encouraging the Greeks, while Zeus favoured the Trojans. In the Odyssey, Poseidon appears hostile to Odysseus, whom he prevents from returning home in consequence of his having blinded Polyphemus, a son of Poseidon by the nymph Thosa.
Being the ruler of the sea (the Mediterranean), he is described as gathering clouds and calling forth storms, but at the same time he has it in his power to grant a successful voyage and save those who are in danger; and all other marine divinities are subject to him. As the sea surrounds and holds the earth, he himself is described as the god [p. 1304] [figure in text: Poseidon. (Dolce Gem. )]
who holds the earth (γαιήοχος), and who has it in his power to shake the earth (ἐνοσίχθων, κινητὴρ γᾶς). He was further regarded as the creator of the horse. It is said that when Poseidon and Athen disputed as to which of them should give the name to the capital of Attica, the gods decided that it should receive its name from the deity who should bestow upon man the most useful gift. Poseidon then created the horse, and Athen called forth the olive-tree, in consequence of which the honour was conferred upon the goddess. According to others, however, Poseidon did not create the horse in Attica, but in Thessaly, where he also gave the famous horses to Peleus. Poseidon was accordingly believed to have taught men the art of managing horses by the bridle, and to have been the originator and protector of horse-races. Hence he was also represented on horseback, or riding in a chariot drawn by two or four horses, and is designated by the epithets ἵππιος, ἵππειος, or ἵππιος ἄναξ. He even metamorphosed himself into a horse for the purpose of deceiving Demeter. The symbol of Poseidon's power was the trident, or a spear with three points, with which he used to shatter rocks, to call forth or subdue storms, to shake the earth, and the like. Herodotus states that the name and worship of Poseidon were brought into Greece from Libya; but he was probably a divinity of Pelasgian origin, and originally a personification of the fertilizing power of water, from which the transition to regarding him as the god of the sea was not difficult. The following legends respecting Poseidon deserve to be mentioned. In conjunction with Zeus he fought against Cronos and the Titans; and in the contest with the giants he pursued Polybotes across the sea as far as Cos, and there killed him by throwing the island upon him. He further crushed the Centaurs when they were pursued by Heracles, under a mountain in Leucosia, the island of the Sirens. He sued, together with Zeus, for the hand of Thetis; but he withdrew when Themis prophesied that the son of Thetis would be greater than his father. When Ares had been caught in the wonderful net by Hephaestus, the latter set him free at the request of Poseidon; but the latter god afterwards brought a charge against Ares before the Areopagus for having killed his son Halirrhothius. At the request of Minos, king of Crete, Poseidon caused a bull to rise from the sea, which the king promised to sacrifice; but when Minos treacherously concealed the animal among a herd of oxen, the god punished Minos by causing his wife Pasipha (q.v.) to fall in love with the bull.
Poseidon was married to Amphitrit, by whom he had three children, Triton, Rhod, and Benthesicym; but he had also a vast number of children by other divinities and mortal women. His worship extended over all Greece and Southern Italy, but he was more especially revered in Peloponnesus and in the Ionic towns on the coast. The sacrifices offered to him generally consisted of black and white bulls; but wild boars and rams were also sacrificed to him. Horse and chariot races were held in his honour on the Corinthian Isthmus. The Panionia, or the festival of all the Ionians near Mycal, was celebrated in honour of Poseidon. In works of art, Poseidon may be easily recognized by his attributes, the dolphin, the horse, or the trident, and he was frequently represented in groups along with Amphitrit, Tritons, Nereds, dolphins. the Dioscuri, Palaemon, Pegasus, Bellerophontes, Thalassa, Ino, and Galen. His figure does not present the majestic calm which characterizes his brother Zeus; but as the state of the sea is varying, so also is the god represented sometimes in violent agitation and sometimes in a state of repose. For the Roman god corresponding to Poseidon, see Neptunus.