A Beltane Fire Festival in Scotland (image source)
All around the world Mayday is celebrated in many different guises, but all the various celebrations have a common root in the pagan festival of renewal that in Western Europe is known as Beltane. The pagan year, sometimes known as the eightfold year, is divided into its main seasons by the two solstices (longest and shortest day) and two equinoxes (when hours of light and darkness are equal). This roughly coincides with the farming calendar with seasons for planting, growing, harvesting and a barren season for ploughing and maintenance.
A secondary calendar (because four feast days is not enough) splits each of these seasons. Beltane (May), Lughnasa (August), Samhain (November) and Imbolc (February) marked the seasons of the herdsmen's year. But what has animal husbandry to do with the good fire (Bel Tane) you might well ask. Dunno. Possibly nobody really does. But one idea that has some traction is that it was delousing day after the animals had been shorn of their winter coats.
Hop over to Authors Den and check out Ian Thorpe's Beltane poem Fires Of Love and the write up of the significance of Beltane to our ancestors.
Fires of Love at Authors Den