Grimm's Household Tales (Edwardes)/The Changeling
A mother once had her child stolen from her by the elves. They took it out of the cradle and placed in its stead a changeling with a large head and staring eyes, that would do nothing but eat and drink. In her distress, she went to one of her neighbours and asked her advice. The neighbour told her to carry the changeling into the kitchen and seat it on the hearth, then to light a fire and boil some water in two egg-shells. That, she said, would make the changeling laugh, and if he once laughed, it would be all over with him. The mother went back and followed out all these directions. As she put the egg-shells with water in them on the fire, the little gnome-child said—
"I am old as the woods,
But from ages of yore,
I never saw shells
Used for boiling before."
and with that he began to laugh. While he was laughing a company of elves came crowding into the kitchen, bringing with them the woman's own child, which they laid down on the hearth. Then they took up the changeling and disappeared with him.