The horse-shoe arch was a common emblem on pagan monuments, and is frequently seen in Caledonian sculptured hieroglyphics, where it is believed to have had a special significance as a protective symbol. Lieutenant-Colonel Forbes Leslie, in “The Early Races of Scotland,” remarks that the horse-shoe arch was probably emblematic of the serpent as a protecting and beneficent power, because this arch closely resembles a peculiar mark or attribute of the so-called _Nagendra_, the hooded serpent-king, a chief deity in the mythical lore of Ceylon. It would appear quite unnecessary to refer to the Cingalese mythology in this connection, inasmuch as the close resemblance between the shape of the horse-shoe and the arched body of a snake has already been commented on. As illustrative of the somewhat unique theory which claims the ancient horse-shoe arch, itself a talismanic symbol, as the original source of all the superstitions associated with the modern iron horse-shoe, it may be appropriate to quote a few lines from the authority above mentioned:— Whatever this figure (the horse-shoe arch) may have represented to our heathen ancestors, it seems very likely that from it the horse-shoe derived its supposed power of promoting the fortune of its possessor and protecting him against threatened calamities, whether designed by men or demons. Superstition clung to the symbol that was hallowed by antiquity, and even impressed this emblem of paganism on the Christianity by which it was superseded. The historian Diodorus Siculus said that the Chaldeans imagined the earth as having the shape of a round boat turned upside down. The boats still used on the rivers Tigris and Euphrates resemble in form a beehive with a considerable bulge in the middle. Gerald Massey (“The Natural Genesis,” vol. ii. p. 63) says that this conception of the earth’s figure corresponds to the Egyptian _Put-sign_ with its hollow underneath. Various forms of this formation of the world are extant. The horse-shoe is one. _Hence its value as a symbol of superstition._ The head-dress of the Egyptian goddess Hathor has the shape of a horse-shoe. The letter omega (Ω) is another form of the same sign. The Rev. C. Vernon Harcourt, in his “Doctrine of the Deluge” (vol. i. p. 141), suggests that the moon was anciently regarded as particularly sacred when in the first quarter, because at that period it resembled most closely the ark of Noah, which was crescent-shaped. Again, the horse-shoe form is believed to be a survival of an ancient religious symbol often seen in Assyrian and Egyptian sculptures, signifying the mystical door of life.