A curious amulet, apparently belonging to the Gnostic variety, and intended to bring success to the owner of a racehorse, is now in the collection of the Metropolitan Museum of Art, in New York. The material is green jasper with red spots. On the obverse the horse is figured with the victor’s palm and the name Tiberis; on the reverse appears the vulture-headed figure of the Abraxas god and the characters, “ZACTA IAW BAPIA,” which have been translated, “Iao the Destroyer and Creator.”[187] Possibly this amulet may have been attached to the horse during his races to insure victory, as we know that amulets of this kind were used in this way. As illustrating the eclectic character of some of the amulets used in the early Christian centuries, we may note one in the Cabinet de Médailles, in Paris. This has upon the obverse the head of Alexander the Great; on the reverse is a she-ass with her foal, and below this a scorpion and the name Jesus Christ. Another amulet of this class, figured by Vettori,[188] also has the head of Alexander on the obverse, while the reverse bears the Greek monogram of the name Christos. After the third or fourth century of our era the art of gem-engraving seems to have been lost, or at least to have been very seldom practised, and it is noteworthy in the matter that after this period writers who treat of the virtues of engraved gems as talismans rarely, if ever, use the words “if you engrave” such or such a figure on a stone, but write “if you find” such a figure. The figures engraved on precious stones were supposed to have a greater or lesser degree of efficacy in themselves independent of the virtues peculiar to the stone on which they were engraved, and this efficacy depended largely upon the hour, day, or month during which the work was executed. For the influence of the planet, star, or constellation which was in the ascendant was thought to infuse a subtle essence into the stone while the appropriate image was being engraved. However, to exert the maximum power, the virtue of the image must be of the same character as the virtue inherent in the material, and the gem became less potent when this was not the case. Certain images, those symbolizing the zodiacal signs for instance, were looked upon as possessing such power that their peculiar nature impressed itself even upon stones inherently of different quality; others again were only efficacious when engraved on stones the quality of which was in sympathy with them.[189]