Cornish Fairies

Margaret Ann Courtney mentions that 'The Pisky's Midwife' is a common story--a mortal is decoyed into fairyland discovers it accidently by rubbing one eye with a bit of soap while washing the baby. Like those who have stolen and applied the green ointment, she loses sight of the eye by a blow from and angry pisky. She meets and recognizes the father or master at a fair where, as usual, he is pilfering. She foolishly asks after the welfare of the mother and child.

Courtney, Cornish Feasts and Folklore, pages 124-125.