"a changeling in a cradle"
In the fairy tale and folkloric traditions, changelings are magical creatures left in the place of human children who have been snatched away by otherworldly beings. Sometimes the changeling child is not a living being but a "stock" -- an enchanted item, such as a piece of wood, that would eventually wither and die. It is believed that the notion of changeling children served to explain the loss of a child to an unexplained ailment, and to explain physical deformities and disabilities in children. In Madame de Villeneuve's "Beauty and the Beast," Beauty is a changeling child, the daughter of a king and a fairy.