by the playwright  Euripides , poet  Theocritus  and Roman epic poet  Virgil . In  Hesiod 's  Theogony , Zeus releases three Cyclopes, the sons of  Uranus  and  Gaia , from the dark pit of  Tartarus . They provide Zeus' thunderbolt, Hades' helmet of invisibility, and Poseidon's trident, and the gods use