HOW TO DETECT CHANGELINGS.
One way of finding out whether children were Changelings or not was to listen to them speaking. If suspected children were heard speaking things above the understanding of children, it was considered a proof that they were changelings. This was a wide-spread belief in Wales.
Fairies did not always come to steal children, however, for they were believed in some places to enter the houses at night to dance and sing until the morning, and leave on the hearth-stone a piece of money as a reward behind them, should they find the house clean; but should it be dirty, they came to punish the servant girl. The good Fairies known as “Bendith y Mamau,” were supposed to rock the infant’s cradle and sweep and clean the house whilst the tired mother slept. And one way of securing their good luck was to leave a little milk for them upon the kitchen table at night.