Greek sea gods conform to a single type: that of Homer's "halios geron" or Old Man of the Sea: Nereus, Proteus, Glaucus and Phorkys. These sea gods are not as powerful as Poseidon, the main god of the oceans and seas. Each one is a shape-shifter, a prophet, and the father of either radiantly beautiful nymphs or hideous monsters (or both, in the case of Phorkys). Nymphs and monsters blur, for Hesiod relates that Phorcys was wed to the "beautiful-cheeked" Ceto, whose name is merely the feminine of the monstrous Cetus, to whom Andromeda was due to be sacrificed. Each appearance in myth
Greek mythology Nereids (who inhabited the sea), river gods, Satyrs, and others. In addition, there were the dark powers of the underworld, such as the Erinyes (or Furies), said to pursue those guilty of crimes against blood-relatives. In order to honor the Ancient Greek pantheon, poets composed the Homeric Hymns (a group of thirty-three songs). Gregory Nagy regards "the larger Homeric Hymns as simple preludes (compared with "Theogony"), each of which invokes one god". The gods of Greek mythology are described as having essentially corporeal but ideal bodies. According to Walter Burkert, the defining characteristic of Greek anthropomorphism is that "the Greek