POSEIDON, in Greek mythology, god of the sea and of water generally, son of Cronus and Rhea, and brother of Zeus and Pluto. The connexion of his name with 7r6<ns, vdvras, wora/i6s, is generally accepted. When the three brothers deposed their father Cronus the kingdom of the sea fell by lot to Poseidon. His home was in a golden palace in the depths of the sea near Aegae in Achaea. In his hand he bore a trident, wherewith he lashed the sea into fury, split the rocks, and caused horses and fountains to spring from them. But, while he caused storms and shipwrecks, he could also send favouring winds; hence he was known as Soter, " the preserver." Another of his titles was Gaeeochos, " the supporter of earth," the sea being supposed to support the earth and keep it firmly in its place. He was the god of navigation and his temples stood especially on headlands and isthmuses. Every occupation connected with the sea was under his protection, and seafaring people, especially the lonians, regarded themselves as his descendants. As god of the sea he disputed with other deities for the possession of the land. Earthquakes were thought to be produced by Poseidon shaking the earth hence his epithet of Enosichthon, " Earth-shaker "- and hence he was worshipped even in inland places which had . suffered from earthquakes. The seismic wave was also his work; the destruction of Helice in Achaea by such a wave (373 B.C.) was attributed to his wrath (Strabo viii. 384). The island of Delos was thought to have been raised by him, and about 198, when a new island appeared between Thera and Therasia, the Rhodians founded a temple of Poseidon on it (Strabo i. 57). Thessaly was said to have been a lake until he opened a way for the waters through the Vale of Tempe ( Herodotus vii. 129). Poseidon was also the god of springs, which he produced by striking the rock with his trident, as he did on the acropolis of Athens when disputing with Athena for the sovereignty of Athens (Herodotus viii. 55; Apollodorus iii. 14). As such he was called Nymphagetes, the leader of the nymphs of springs and fountains, a god of fresh water, probably his original character, and in this connexion was <urdX/xios (phytalmius) , a god of vegetation, frequently associated with Demeter. In regard to the contest with Athena, it is probable that Poseidon is really Erechtheus, a local deity ousted by Athena and transformedinto an agricultural hero. Dr Farnell, however, holds that Erechtheus and Poseidon were originally independent figures, and that both Erechtheus and Athena were prior to Poseidon, As he gave, so he could withhold, springs of water; thus the waterless neighbourhood of Argos was supposed to be the result of his anger. Black bulls, symbolical of the stormy sea, were sacrificed to him, and often thrown alive into rivers; in Ionia and Thessaly bull-fights took place in his honour; at a festival of his at Ephesus the cupbearers were called " bulls," and the god himself was surnamed " Bull Poseidon." The horse was especially associated with his worship; he was said to have produced the first horse by striking the ground in Thessaly with his trident (Virgil, Georgics, i. 12). At the fountain of Dine in Argolis horses bitted and bridled were sacrificed to him by being drowned (Pausanias viii. 7, 2), and similarly Sextus Pompeius sought to propitiate him by throwing horses into the sea (Dio Cassius xlviii. 48). He bore the surname of " Horse Neptune " (HofftiSuv turrtos), and was regarded as the tamer as well as the creator of the steed. In the deme of Colonus he was worshipped with Athena, the reputed inventor of the bridle. Various explanations of the title IViuos have been given: (i) that the horse represented the corn-spirit; (2) the resemblance of the crested waves to horses; (3) the impression of horses' hoofs near the god's sacred springs, and the shaking of the earth by them when galloping (see Farnell, Cults of the Greek States, iv. 20). Poseidon plays a considerable part in Greek legend. In the Trojan War he takes the side of the Greeks, because he had been cheated of his reward by Laomedon, king of Troy, for whom he had built the walls of the city. The binding of his son Polyphemus by Odysseus brings upon the hero the wrath of Poseidon, from which he is only protected by the united influence of the rest of the gods. He is famous for his numerous amours, especially with the nymphs of springs and fountains; his offspring were mostly wild and cruel, like the sea the Laestrygones, Polyphemus, Antaeus, Procrustes and the like. He was worshipped as a national god by the lonians, who took his worship over with them from Peloponnesus to Asia Minor. His chief sanctuary was at Mycale, where the Panionia, the national festival of the lonians, was held. Other seats of his worship were in Thessaly, Boeotia and Peloponnesus. At Taenarum in Laconia he had a famous cave-like temple, with an asylum, and on the island of Tenos he was worshipped as the physician, probably in reference to the health-giving properties of the sea air. By far the most famous of his festivals was that celebrated every alternate year on the isthmus of Corinth, at which the " Isthmian games " were held. Here a colossal statue of him was set up in bronze by the Greeks after their victory over the Persians. The horse, the dolphin (the symbol of the calm sea) and the pine-tree, with wreaths of which the Isthmian victors were crowned, were sacred to him. Horses and black bulls, boars and rams were offered to him, sometimes human beings. His attributes are the trident and the dolphin (sometimes the tunny fish.)
As represented in art Poseidon resembles Zeus, but possesses less of his majestic calm, his muscles are more emphasized, and his hair is thicker and somewhat dishevelled. He is generally naked; his right leg rests on a rock or the prow of a ship ; he carries a trident in his hand, and is gazing in front of him, apparently out to sea; sometimes he is standing on the water, swinging his trident, or riding in his chariot over the waves, accompanied by his wife Amphitrite, the Nereids and other inhabitants of the sea. It is in keeping with his restless character that he is rarely found sitting. He sometimes wears a long robe, sometimes a light scarf. Scopas, in a famous group, represented him surrounded by the denizens of the sea, escorting Achilles to the islands of the blest. In modern Greece St Nicholas has taken the place of Poseidon as patron of sailors. But the Zacynthians have a special seagod, half man, half fish, who dwells under the sea, rides on dolphins or in a car drawn by dolphins, and wields a trident. By the Romans Poseidon was identified with Neptune (q.v.).
See E. Gerhard, Uber Ursprung, Wesen und Geltung des Poseidon (1851), with references to authorities in conveniently arranged notes; Preller- Robert, Griechische Mythologie (1894); O. Gruppe, Griechische Mythologie (1906), vol. ii.; and especially L. R. Farnell, Cults of the Greek States (1907), vol. iv., where special attention is drawn to the ethnological aspect of the cult of Poseidon.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)