As a universal symbol of opening and new possibilities it’s not surprising that there are many superstitions concerning doors and spirits. Most of these superstitions are concerned with keeping ghosts from entering homes or letting ghosts escape to the afterlife. For example, it is widely thought unlucky to enter a house via the back door, as traditionally corpses are carried out the back door.
Opening doors and windows when there has been a death in the house is thought to help the spirit leave the corpse. A circle chalked on a door is believed to prevent evil spirits from entering, and slamming a door several times during a row is believed to trap a ghost between the frame and the door and force it to leave.