Witchcraft—the conscious or unconscious exercise of a power peculiar to some persons, in greater or lesser degree, of controlling little-heeded or understood laws of nature—was ever common in Ireland. Witches were Pitags, Buitseachs, or Taut-ags. These had the mark, or "Seal of the Devil," in reddening skin, which would retain for hours an indentation upon it. Recently, it has been ascertained by a philosopher, that a sensitiveness in certain individuals exists even beyond their bodies, so that they suffer without being actually touched.

In a tradition respecting Conn of the Hundred Battles, the hero Eogan was told by three women that he should be slain in the coming fight. Upon his asking their names, they replied, "Our names are Ah, Lann, and Leana; we are daughters of Trodan the Magician." A witch, who sought to rescue a hero surrounded by foes, induced the tribesmen to leave him and attack some rocks, which they were hypnotized to believe were armed soldiery. The witches tied knots in a string, and breathed on them with a curse upon the object of their hateful incantation. Some persons, however, were clever enough, when finding such a charmed string, to undo the knots, and so prevent the calamity. The Koran contains a prayer for delivery "from the mischief of women blowing on knots."