When a modern Egyptian returns from a pilgrimage to Mecca, he fastens above the entrance of his house a branch of the aloe, which is not only a proof of his religious zeal in having accomplished the holy journey, but is also reckoned a protection against objectionable spiritual intruders, and is, therefore, seen in Cairo over the doors of the houses both of Christians and Jews. In northern Scotland, formerly, a branch of the rowan-tree was placed over a farmhouse door, after having been waved while the words “Avaunt, Satan!” were solemnly pronounced.[197] About the year 1850 the Rev. Andrew A. Bonar, who was then assistant minister in Collace Parish, Perthshire, Scotland, found the custom of displaying horse-shoes on the doors of farm buildings so prevalent that he thought it his duty to remonstrate against a practice savoring of paganism. But his efforts in this direction, though hardly crowned with success, were yet not wholly without avail, for his superstitious parishioners removed the guardian horse-shoes from the outsides of the doors, and nailed them up on the insides.[198] The _raison d’être_ of the horse-shoe at the entrance of shops and other frequented buildings has been attributed to a belief that, among the many people continually passing through the doorway, some one might, unobserved, bring in ill-luck or work mischief. But these safeguards not only form a sufficient barrier against obnoxious hags and sorcerers, but are potent against ghosts and all manner of evil creatures. When the Oxford undergraduate “sports his oak” to prevent the untimely entrance of dunning tradespeople, he shuts out friendly visitors as well; but the faithful horse-shoe, by a process of natural selection, debars only objectionable spirits, and is a formidable obstacle to the demon of ill-luck. XV. THE LUCKY HORSE-SHOE IN GENERAL He laughs like a boor who has found a horse-shoe.—_Dutch proverb._ Throughout Germany the belief obtains that a horse-shoe found on the road, and nailed on the threshold of a house with the points directed outward, is a mighty protection not only against hags and fiends, but also against fire and lightning; but, _reversed_, it brings misfortune. In eastern Pennsylvania, however, even in recent times, the horse-shoe is often placed with the prongs pointing inward, so that the luck may be spilled into the house. The horse-shoe retains its potency as a charm on the sea as well as on land, and it has long been a practice among sailors to nail this favorite amulet against the mast of a vessel, whether fishing-boat or large sea-going craft, as a protection against the Evil One. The shoe of a “wraith-horse,” the mythical offspring of a water-stallion, is especially esteemed by Scotch mariners for this purpose.[199]