Horseshoes are a traditional sign of good luck. Most believe this comes from the fact that the horseshoe is shaped like the crescent moon, time of prosperity and good fortune. One legend says that the Devil called on St. Dunstan, who was skilled in shoeing horses. St. Dunstan recognized the Devil and fastened him to a wall. He then set to work with such roughness that the Devil roared for mercy. St Dunstan turned the Devil loose after making him promise never to enter a home on which a horseshoe was fixed. Witches fear horses, so they are also turned away by a door with a horseshoe mounted on it.
The big issue regarding horseshoes is whether they should be hung points up or points down. The original superstition was that the horseshoe is points up to keep the luck from pouring out. Despite this view most buildings with horseshoes in their sign hang them the opposite way. The Horseshoe Casino in Las Vegas hangs it with the arc on top. (They may be hoping their customers luck runs out but this is usually not something you advertise in your sign).
Finger rings made of horseshoe nails are said to ward off bad luck. Rubbing two horseshoes together is said to bring good luck.
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