In Greek mythology, Acis (Ancient Greek: Ἄκις) is a Sicilian youth, son of Faunus and the river-nymph Symaethis, beloved of the Nereid Galatea. In Ovid's Metamorphoses the jealous Cyclops Polyphemus crushes him with a boulder from Mount Etna; Galatea transforms his blood into the river Acis and Acis himself into the stream's horned god. The tale is not securely attested before Ovid and became a major theme in later poetry, opera, and art.
Adapted from Wikipedia, "Acis and Galatea" · CC BY-SA 4.0
I.Mythology
Galatea, daughter of Nereus and Doris, was already known to Homer and Hesiod as one of the fairest Nereids. Theocritus has the Sicilian Cyclops Polyphemus court her. Ovid first joins her to Acis: while the lovers lie by the sea, Polyphemus spies them, tears a boulder from Etna, and crushes Acis. Galatea turns the trickling blood into the sparkling Sicilian river Acis and transforms her lover into the river's deity, larger and deep blue of face but otherwise recognisable.
Athenaeus reports that Philoxenus of Cythera may have invented related material as satire against Dionysius I of Syracuse and a concubine named Galatea; others explain the tale as an aition for a shrine of Galatea on Etna. A later tradition has Galatea yield to Polyphemus and bear Galas or Galates, ancestor of the Gauls, a genealogy known to the Sicilian historian Timaeus.
II.Reception
From the Renaissance onward the story inspired narrative poems (notably Góngora's Fábula de Polifemo y Galatea), operas and pastorals by Lully, Handel, Bononcini, Porpora, and Haydn, and countless paintings and garden sculptures — from Poussin and Claude Lorrain to Raphael's Triumph of Galatea and the Acireale statue group at the supposed site of the transformation.