While there was a tendency to attribute the virtues originally ascribed to one particular stone to others of the same or similar color and appearance, certain stones were regarded as possessing special virtues not commonly attributed to others. A notable instance of this is the quality supposed to inhere in the turquoise. This stone was known in Egypt from a very early period and is later described by Pliny under the name of _callais_. For Pliny, and for all those who derived their information from him or from the sources he used, the turquoise only participated in the virtues assigned to all blue or greenish-blue stones; but from the thirteenth century, when the name turquoise was first employed, we read that the stone possessed the power to protect the wearer from injury by falling, more especially from horseback; later, this was extended to cover falls from a building or over a precipice. A fourteenth century authority, the “Lapidaire” of Sir John Mandeville, states that the turquoise protected horses from the ill-effects resulting from drinking cold water when overheated by exertion, and it is said that the Turks often attached these stones to the bridles and frontlets of their horses as amulets. They are also so used in Samarcand and Persia. We might therefore be justified in supposing that the turquoise was originally used in the East as a “horse-amulet,” and the belief in its power to protect from falls may have arisen from the idea that it rendered the horse more sure-footed and enduring. As the horse was often regarded as a symbol of the sun in its rapid course through the blue heavens, the celestial hue of the turquoise may have caused it to be associated in some way with the horse. We can only hazard this as a plausible conjecture. Probably the earliest notice of the peculiar superstition in regard to the turquoise—namely, that it preserves the wearer from injury in case of falling—is contained in Volmar’s thirteenth century “Steinbuch,” where we read: Whoever owns the true turquoise set in gold will not injure any of his limbs when he falls, whether he be riding or walking, so long as he has the stone with him.[157]