The ancient rath, or fort, or liss, generally enclosed about half an
acre, and had two or more ramparts, formed by the heads of the tribe
for defence. But when the race of the chieftains died out, then the
Sidhe crowded into the forts, and there held their councils and revels
and dances; and if a man put his ear close to the ground at night he
could hear the sweet fairy music rising up from under the earth.
The rath ever after is sacred to the fairies, and no mortal is allowed
to cut down a tree that grows on it, or to carry away a stone. But
dangerous above all would it be to build on a fairy rath. If a man
attempted such a rash act, the fairies would put a blast on his eyes,
or give him a crooked mouth; for no human hand should dare to touch
their ancient dancing grounds.
It is not right, the people say, to sing or whistle at night that old
air, “The pretty girl milking her cow;” for it is a fairy tune, and
the fairies will not suffer a mortal to sing their music while they
are dancing on the grass. But if a person sleeps on the rath the music
will enter into his soul, and when he awakes he may sing the air he has
heard in his dreams.
In this way the bards learned their songs, and they were skilled
musicians, and touched the harp with a master hand, so that the fairies
often gathered round to listen, though invisible to mortal eyes.