According to the Celtic legends, on the 31th of October, the Eve of Halloween, the Druids - spirits of wild nature - met in the oaks on the tops of heels (the Celts believed oak-trees to be holy ones), started a fire and made sacrifices to please the demons.
In the morning the Druids presented to people pieces of coal of their bonfires, so that the other could warm their homes. The Druids' fire warmed the homes during long and cold winter and protected these families from demons.