Beltane, festival held on the first day of May in Ireland and Scotland, celebrating the beginning of summer and open pasturing. Beltane is first mentioned in a glossary attributed to Cormac, bishop of Cashel and king of Munster, who was killed in 908. Cormac describes how cattle were driven between two bonfires on Beltane as a magical means of protecting them from disease before they were led into summer pastures—a custom still observed in Ireland in the 19th century. Other festivities included Maypole dances and cutting of green boughs and flowers.
In early Irish lore a number of significant events took place on Beltane, which long remained the focus of folk traditions and tales in Ireland, Scotland, and the Isle of Man. As did other pre-Christian Celtic peoples, the Irish divided the year into two main seasons. Winter and the beginning of the year fell on November 1 (Irish: Samain) and midyear and summer on May 1 (Irish: Beltaine). These two junctures were thought to be critical periods when the bounds between the human and supernatural worlds were temporarily erased; on May Eve witches and fairies roamed freely, and measures had to be taken against their enchantments.
Cormac derives the word Beltaine from the name of a god Bel, or Bil, and the Old Irish word tene, “fire.” Despite linguistic difficulties, a number of 20th-century scholars have maintained modified versions of this etymology, linking the first element of the word with the Gaulish god Belenos (Irish: Belenus).