If the fairies wished to seize a mortal—which power they had as the sun-god could take men to himself—they caused him to give them certain tokens by which he delivered himself into their hands. They might be milk and fire—
"Maire Bruin:
A little queer old woman cloaked in green,
Who came to beg a porringer of milk.
Bridget Bruin:
The good people go asking milk and fire
Upon May Eve—woe to the house that gives,
For they have power over it for a year."
Yeats: Land of Heart's Desire.
or one might receive a fairy thorn such as Oonah brings home, which shrivels up at the touch of St. Bridget's image;
"Oh, ever since I kept the twig of thorn and hid it, I have seen strange things, and heard strange laughter and far voices calling."
Warren: Twig of Thorn.
or one might be lured by music as he stopped near the fort to watch the dancing, for the revels were held in secret, as those of the Druids had been, and no one could look on them unaffected.
A story is told of Paddy More, a great stout uncivil churl, and Paddy Beg, a cheerful little hunchback. The latter, seeing lights and hearing music, paused by a mound, and was invited in. Urged to tell stories, he complied; he danced as spryly as he could for his deformity; he sang, and made himself so agreeable that the fairies decided to take the hump off his back, and send him home a straight manly fellow. The next Hallowe'en who should come by the same place but Paddy More, and he stopped likewise to spy at the merrymaking. He too was called in, but would not dance politely, added no stories nor songs. The fairies clapped Paddy Beg's hump on his back, and dismissed him under a double burden of discomfort.
A lad called Guleesh, listening outside a fort on Hallowe'en heard the spirits speaking of the fatal illness of his betrothed, the daughter of the King of France. They said that if Guleesh but knew it, he might boil an herb that grew by his door and give it to the princess and make her well. Joyfully Guleesh hastened home, prepared the herb, and cured the royal girl.