Whatever may be the origin of the superstitious employment of the horse-shoe, its adoption as a token of good luck appears to be comparatively modern, its earliest use having been for the exclusion of witches, evil spirits, and all such uncanny beings.
Before leaving the subject an extract may be given from an article in the "London World," August 23, 1753, against the repeal of the so-called Witch Act, wherein the writer offers the following satirical advice to whomever it might concern:--
To secure yourself against the enchantments of witches, especially if you are a person of fashion and have never been taught the Lord's Prayer, the only method I know of is to nail a horse-shoe upon the threshold. This I can affirm to be of the greatest efficacy, insomuch that I have taken notice of many a little cottage in the country with a horse-shoe at its door where gaming, extravagance, Jacobitism, and all the catalogue of witchcrafts have been totally unknown.
The world moves and civilization progresses, but the old superstitions remain the same. The rusty horse-shoe found on the road is still prized as a lucky token, and will doubtless continue to be so prized; for human nature does not change, and superstition is a part of human nature.