 It was composed soon after his ""La belle dame sans merci"" and his odes on Melancholy, on Indolence, on a Grecian Urn and to a Nightingale and just before "Ode to Autumn".The poem tells how the god Hermes hears of a nymph who is more beautiful than all.Hermes, searching for the nymph, instead comes across Lamia, trapped in the form of a serpent.