The Lamia of folklore is a faery creature half-serpent and half-woman. Like harpies, they are said to seduce men with the object of killing them. The name of Lamia was also connected to a snake goddess from Crete, but the Greek myths portrayed her as one of the many nymphs that Zeus had an affair with, with the usual consequence of Hera changing them into something. In the case of Lamia, she was changed into a serpent and forced to eat her children. Driven mad, she developed a taste for children and the flesh of mortal men.

In a poem called Lamia, by John Keats, a Lamia falls in love with a mortal and she changes into the guise of a woman, but is revealed to be a serpent on their wedding day. There is a stanza in the poem which takes place after she has fallen in love, and she has gone to the place where her beloved dwells, and undergoes the transformation to a human semblance so he can behold her as a woman:

Whither fled Lamia, now a lady bright, A full-born beauty new and exquisite? She fled into that valley they pass o’er Who go to Corinth from Cenchreas’ shore; And rested at the foot of those wild hills, The rugged founts of the Peraean rills, And of that other ridge whose barren back Stretches, with all its mist and cloudy rack, South-westward to Cleone. There she stood About a young bird’s flutter from a wood, Fair, on a sloping green of mossy tread, By a clear pool, wherein she passioned To see herself escap’d from so sore ills, While her robes flaunted with the daffodils.

The scene in this work of art shows her in mid-transformation, by the side of a pool, into which she will gaze at her new form.