POSEIDONE (Ποσειδών). — God of the waters, whose prerogative seems symbolized by the root common to his name (πόσις, ποντίζω, πάνταμαις; V. H. L. Ahrens, Über den Namen des Poseidon, in Philologus, 23 [1866], p. 1 ff.).
Originally, his dominion embraced the whole earth, which experienced his power as manifested in seismic tremors (ἐννοσίγαιος, ἐνοσίγθων γαύργος). One among the many testimonies confirming this character of earth-shaker is the sanctuary that the Rhodians, under the epithet ἀσφάλιος, erected to him on a new little island formed near Thera, one of the Sporades, following a volcanic eruption (Strabo, I, 3, 16; ἀσφάλιος = terram stabilens, according to Macrobius, Sat., I, 17, 22). Elsewhere, as at Tresene, he was regarded as the god of vegetation (φυτάλμιος: Plutarch, Thes., 6). Returning to the primitive conception of a terrestrial god, P. was venerated chiefly in Thessaly, Boeotia (Etymol. mag., 547, 16), and the Peloponnese (Diodorus Siculus, XV, 40). Traces of fetishism are found in Arcadia, at Thelpusa (Pausanias, VIII, 25, 4, 10) and at Phigalia (ibid., VIII, 5, 5; 42, 4), where, in association with the cult of Demeter Melaina, the god appears in the form of a horse (P. Hippios at Lycosura, Mantinea, etc. cf. Iliad, XXIII, 584; Hymni Homerici, 22, V. 5).
It is probable that the Thessalian and Boeotian colonists who, driven by new invasions, emigrated to the coasts of Asia Minor transformed P.’s archaic prerogative as protector of springs and rivers into that of ruler of the sea. Indeed, in Homer (Iliad, XV, 187 ff.) P. is
one of the three sons of Kronos and possesses in the sea the clearly defined sphere of his dominion; in the later tradition, the entire retinue of marine divinities would be attributed to him (husband of Amphitrite, etc.). His cult was widespread in the various localities of Greece and Ionia, where temples and sanctuaries were erected to him. The one on the Isthmus of Corinth was famous. For some time already, regarded as an indigete god together with Athena, he had been venerated on the Acropolis of Athens as P.-Erechtheus in the temple of the same name (on an earlier sanctuary ἀρχαῖος νέος; V. W. Judeich Topographie von Athen, Munich 1931, p. 259 ff.). At Rome, under the name Neptunus, from the Etruscan “nePuns,” P. possessed the same attributes as god of the sea, and the Neptunalia were celebrated in his honor on 23 July, becoming more important after the victory at Actium. As Neptunus equester he was assimilated, in a certain manner, to the Latin god Connus. An altar and a temple of Neptune stood near the Circus Flaminius (Livy, XXVIII, 11, 4; Pliny, Nat. hist., XXXVI, 26; CIL, VI, 8423). Classical art generally depicts P. as a seated man in the fullness of maturity, with the attributes of the trident and dolphin.