According to the Celtic pagan religion,known as "Druifism" the spirits of those who had died in the preceding year roamed the earth on Samhain evening. The Celts sought to ward off these spirits with offering of food and drink. They also built bonfires at sacred hilltop sites and preformed rituals,involving human and animal sacrifices,to honor Druid. Still today,these things are being practiced. It was an ancient Druid custom set up for human sacrifices on Halloween night. Druids offered children in sacrifices. The trick-or-treat custom was created by the Druids. When they went to a home and demanded a child or virgin for sacrifice,the victim was the Druids treat. In exchange,they would leave a jacko'- lantern with a lighted candle made of human fat to prevent those inside from being killed by demons that night. When some unfortunate couldn't meet the demands of the Druids,then it was time for the trick. A symbolic hex was drawn on the front door. That night Samhain or his demons would kill someone in that home. This same thing is going on today,only it's much more subtle.