By the time Christianity came to the British Isles, local folk had already been celebrating their own festival of the dead on Samhain (November 1, the Celtic new year). According to author Jack Santino in "Halloween and other Festivals of Death and Life" (University of Tennessee Press), "Many traditional beliefs and customs associated with Samhain, most notable that night was the time of the wandering dead, the practice of leaving offerings of food and drink to masked and costumed revelers, and the lighting of bonfires, continued to be practiced on 31 October."

 

In other words, the Christian church incorporated local Irish, Scottish, and Welsh pagan traditions into one of its own holy days. Just as the old fertility symbols of the rabbit and the evergreen tree became parts of Easter and Christmas, so have the symbols of the end of the fall harvest season and the coming of darkness become parts of a modern western-world celebration.