Sometimes the fairies fancy mortals, and carry them away into their
own country, leaving instead some sickly fairy child, or a log of wood
so bewitched that it seems to be a mortal pining away, and dying, and
being buried. Most commonly they steal children. If you "over look a
child," that is look on it with envy, the fairies have it in their
power. Many things can be done to find out in a child a changeling,
but there is one infallible thing--lay it on the fire with this
formula, "Burn, burn, burn--if of the devil, burn; but if of God and
the saints, be safe from harm" (given by Lady Wilde). Then if it be a
changeling it will rush up the chimney with a cry, for, according to
Giraldus Cambrensis, "fire is the greatest of enemies to every sort of
phantom, in so much that those who have seen apparitions fall into a
swoon as soon as they are sensible of the brightness of fire."
Sometimes the creature is got rid of in a more gentle way. It is on
record that once when a mother was leaning over a wizened changeling
the latch lifted and a fairy came in, carrying home again the
wholesome stolen baby. "It was the others," she said, "who stole it."
As for her, she wanted her own child.
Those who are carried away are happy, according to some accounts, having
plenty of good living and music and mirth. Others say, however, that
they are continually longing for their earthly friends. Lady Wilde gives
a gloomy tradition that there are two kinds of fairies--one kind merry
and gentle, the other evil, and sacrificing every year a life to Satan,
for which purpose they steal mortals. No other Irish writer gives this
tradition--if such fairies there be, they must be among the solitary
spirits--Pookas, Fir Darrigs, and the like.