Beltane — from the Old Irish Beltaine, possibly meaning "bright fire" (from bel, bright or shining, and teine, fire) — is one of the four major festivals of the ancient Irish calendar, documented in medieval Irish literature and law texts. It marked the beginning of summer — the cétsamhain, the first of summer — when cattle were driven from their winter enclosures to the summer pastures.
The earliest written references to Beltane date from the 10th-century Irish text Sanas Cormaic (Cormac's Glossary), which describes the druids lighting two great fires and driving cattle between them — the fire and its smoke purifying the animals against disease for the coming summer. The 12th-century Dindsenchas (the lore of notable places) and the Book of Leinster confirm the festival's importance in Irish medieval culture. Beltane was one of the four principal divisions of the Irish year, alongside Samhain (1 November), Imbolc (1 February) and Lughnasadh (1 August).
The festival was widespread across the Celtic world — cognate celebrations existed in Scotland (Bealltainn), the Isle of Man (Boaltinn) and Wales (Calan Mai). The Scottish Highlands maintained Beltane traditions — particularly the lighting of the tein-éigin, the "need-fire" produced by friction — well into the 18th and 19th centuries, documented by folklorists including Alexander Carmichael in the Carmina Gadelica.
The festival occupied the astronomical midpoint between the spring equinox (Ostara, c.21 March) and the summer solstice (Litha, c.21 June) — placing it at the moment when the natural world reaches its first great fullness. The hawthorn tree — the May tree, which blooms precisely at this time — was Beltane's sacred plant. Its white blossom carpeting the hedgerows was the natural signal that Beltane had arrived. It was considered deeply unlucky to bring hawthorn blossom indoors — its power belonged to the wild, liminal spaces of the festival.