In Greek mythology Leda was the wife of Tyndareus, King of Sparta. While bathing in the river Eurotas, Zeus seduced her in the guise of a swan, after which Leda laid an egg from which the twins, Castor and Polydeuces (Pollux) were born. Cf. M. B. Comstock and C. C. Vermeule, Sculpture in Stone, Museum of Fine Arts, Boston, 1976, p. 29, no. 37 for a similar Greek fragment.