Walking Under Ladders
Accidents happen. When someone is working a few feet off the ground on top of a ladder, it seems like a logical idea to avoid getting in the way in case something were to fall.
But the origin of this common superstition comes from the ancient belief in the sanctity of the trinity. A ladder leaned against a wall or standing on its own forms a triangular space–the triangle being the common symbol of the Holy Trinity. If one passed through this space, it was considered an entrance to the realm of supernatural forces and a disruption of the protection the trinity provides.