It will suffice merely to allude to the theory of the phallic origin of the superstitious use of the horse-shoe, a branch of our subject capable of much elaboration. The horse-shoe is still the conventional figure for the yoni (a phallic emblem) in modern Hindu temples. This theory is discussed in "Ancient Faiths embodied in Ancient Names," by Thomas Inman, M. D., London, 1873; and in "A Discourse on the Worship of Priapus," by Richard Payne Knight, Esq., London, 1865.
Phallic ornaments are of great antiquity, and amulets of this character have been found in the earliest Etruscan tombs. Specimens are also to be seen in the various Italian museums.
The yoni symbol guards the entrances of ancient temples in Mexico and Peru, as well as in India.
Ornate Mexican sacred stones of the horse-shoe form, relics of the ancient Maya tribes, are classed in the National Museum at Washington, D. C., as representative of fecundity and nature-worship; and horse-shoe symbols are found in Aztec manuscripts relating to agriculture as signs of abundance.
Phallic charms are seen above the entrances of houses and over tent-doors in north Africa to avert the evil eye, and to bring health and good fortune. Much information on this subject may be found in a chapter on serpent and phallic worship in "Rivers of Life," by Major General J. G. R. Forlong, London, 1883; and in an essay on "Phallism in Ancient Religions," by C. Staniford Wake, 1888.
On a curious tablet found near a prehistoric mound in the vicinity of the village of Cahokia, Saint Clair County, Illinois, are portrayed human faces with bird-like profiles, diamond-shaped eyes, and low foreheads surmounted by ornamental crowns or head-dresses. The mouths are wide open, and in front of them are represented symbols having a well-defined horse-shoe form. These symbols, although probably of phallic origin, are thought to signify the principle of life residing in the breath, just as in India the horse-shoe is an emblem of the soul.