Your wife's a witch, man; you should nail a horse-shoe on your chamber-door.--SIR WALTER SCOTT, Redgauntlet.
As a practical device for the protection of horses' feet, the utility of the iron horse-shoe has long been generally recognized; and for centuries, in countries widely separated, it has also been popularly used as a talisman for the preservation of buildings or premises from the wiles of witches and fiends.
To the student of folk-lore, a superstition like this, which has exerted so wide an influence over men's minds in the past, and which is also universally prevalent in our own times, must have a peculiar interest. What, then, were the reasons for the general adoption of the horse-shoe as a talisman? It is our purpose to consider the various theories seriatim.
Among the Romans there prevailed a custom of driving nails into cottage walls as an antidote against the plague. Both this practice and the later one of nailing up horse-shoes have been thought by some to originate from the rite of the Passover. The blood sprinkled upon the doorposts and lintel at the time of the great Jewish feast formed the chief points of an arch, and it may be that with this in mind people adopted the horse-shoe as an arch-shaped talisman, and it thus became generally emblematic of good luck.
The same thought may underlie the practice of the peasants in the west of Scotland, who train the boughg of the rowan or mountain-ash tree in the form of an arch over a farmyard gate to protect their cattle from evil.