The roots of Hallowe'en lie in the ancient pre-Christian Celtic festival of Samhain, a feast to mark the death of the old year and the birth of the new. It was believed that on this night the veil separating the worlds of the living and the dead grew thin and ruptured, allowing spirits to pass through and walk unseen but not unheard amongst men. The advent of Christianity saw the pagan festival subsumed in All Souls' Day, when across Europe the dead...