The Celtic calendar had two main seasons, warm and cold. The end of the cold season and the beginning of summer were marked by one of the most important festivals of the year, Bealtaine. The corresponding festival for the end of the Summer and beginning of the winter was Samhain which has now become Halloween.
Bealtaine traditionally fell on the first of May and was highly symbolic for the indigenous population of Ireland. This corresponded to the date when cattle could be driven to open grazing and was therefore a time of great importance for pastoralist societies. The lighting of great fires in prominent locations was central to the celebration of this festival, presumably to reflect the rebirth and rejuvenation of the sun. It was also customary to drive cattle between large fires in order to protect them from disease. TGE Powell in his book The Celts believes that the word is a combination of the celtic word for fire (tine) and reference to a god called Belenus known widely in Northern Italy, south-eastern Gaul, Nordicum and south-west Britain. Belenus is thought to have been a sun-god and his name is believed to have meant ‘Brilliant’ or ‘Bright’ one. In modern Irish Bealtaine is still the name given to the month of May.
More recently a particular raucous festival has become very popular in Edinburgh know as Beltane which involves naked dancers, drums and massive fires on Carlton Hill on the eve of the 1stof May.