SAMHAINE - NOVEMBER 1ST
This marked the first day of the Celtic New Year (beginning at sunset on October 31st). During this festival, new laws were made, the tribal chiefs met and members of the tribes were initiated as warriors. Also during this festival it was believed that the doors to the Otherworld opened and those that had passed on could cross into the material world and avenge wrongs that had been done to them. This went on through the evening of October 31st, until the evening of November 1st. All fires were extinguished at this time and re-lit from a ceremonial fire tended by the druids.
The Christian Church incorporated this festival - hence we now have All Hallows' Day on November 1st and All Saints Day on November 2nd. Halloween on October 31st springs from this festival as well.