The English fern called moonwort (_Botrychium lunaria_) is thought to owe its reputed magical powers to the crescent form of the segments of its frond. Some writers regard it as identical with the martagon, an herb formerly much used by sorcerers; and also with the Italian _sferracavallo_. According to the famous astrologer and herbalist, Nicholas Culpepper, moonwort possessed certain occult virtues, and was endowed with extraordinary attributes, chief among them being its power of undoing locks and of unshoeing horses. The same writer remarked that, while some people of intelligence regarded these notions with scorn, the popular name for moonwort among the countryfolk was “unshoe-the-horse.”[57] Du Bartas, in his “Divine Weekes,” says in reference to this plant:— Horses that, feeding on the grassy hills, tread upon moonwort with their hollow heels, though lately shod, at night go barefoot home, their maister musing where their shoes become. O moonwort! tell me where thou hid’st the smith, hammer and pinchers, thou unshodd’st them with. The horse-shoe has sometimes been identified with the cross, and has been supposed to derive its amuletic power from a fancied resemblance to the sacred Christian symbol. But inasmuch as it is difficult to find any marked similarity in form between the crescent and the cross, this theory does not appear to warrant serious consideration. VI. IRON AS A PROTECTIVE CHARM Some writers have maintained that the luck associated with the horse-shoe is due chiefly to the metal, irrespective of its shape, as iron and steel are traditional charms against malevolent spirits and goblins. In their view, a horse-shoe is simply a piece of iron of graceful shape and convenient form, commonly pierced with seven nail-holes (a mystic number), and therefore an altogether suitable talisman to be affixed to the door of dwelling or stable in conformity with a venerable custom sanctioned by centuries of usage. Of the antiquity of the belief in the supernatural properties of iron there can be no doubt. Among the ancient Gauls this metal was thought to be consecrated to the Evil Principle, and, according to a fragment of the writings of the Egyptian historian Manetho (about 275 B. C.), iron was called in Egypt the bone of Typhon, or Devil’s bone, for Typhon in the Egyptian mythology was the personification of evil.[58] Pliny, in his “Natural History,” states that iron coffin-nails affixed to the lintel of the door render the inmates of the dwelling secure from the visitations of nocturnal prowling spirits.