The ancient Gaelic calendar had four major festivals each year, dictated by the seasons.
Lughnasa, which celebrated the beginning of the harvest, was marked by festive gatherings in late summer, often on the tops of hills. It survives today in some places in the form of religious pilgrimages around that time, the annual climbing of Croagh Patrick, perhaps, being an example.
Samhain is still recalled in the rites we now associate with Hallowe'en, and the less familiar Imbolg, the start of the agricultural year, survives in the customs which surround St Bridget's Day; it was marked by weaving crosses of a distinctive style with rushes, which were then hung in houses to provide protection for the coming growing season.
But perhaps the most important festival of all was Bealtaine, the beginning of the summer, which we know as May Day. It was widely celebrated, both here and on the Continent, by lighting fires; indeed the second half of the name Bealtaine derives from the Irish word for "fire", and is said to recall the ancient custom of purifying cattle by driving them between two bonfires.
In the Christian calendar, May Day is the feast of Saint Walpurga, but the images associated with her name are far from Christian. In ancient times, the eve of May Day was Walpurgisnacht. It was believed that on this night every year witches and other evil creatures of the occult were free to roam the world and cast their nasty spells on the poor defenceless people in their villages.
Even today, in parts of Europe, the bonfires on Walpurgisnacht are lit with the intention of warding off these evil spirits and protecting the local people from their malign influence.
On Walpurgisnacht, in high and lonely places "midnight shout and revelry and tipsie dance" took place as the 12 most wicked of the witches formed a "coven" and led the celebration of a witches' sabbath. Macbeth imagined such a scene the night he murdered Duncan, recalling Hecate, the Greek goddess of the night, who was the queen of ghosts and magic and the protector of enchantresses and witches:
Now o'er the one half-world
Nature seems dead, and wicked dreams abuse
The curtain'd sleep; witchcraft celebrates
With pale Hecate's offerings.
But on a lighter note, in olden times May Day was also the festival of chimney sweepers everywhere. On May 1st, they would bedeck themselves in brightly-coloured clothes, blacken their faces with their stuff-in-trade, trim their hats and coats with golden ribbons, and dance and frolic in the city streets.