Naturally, many of the ancient gems which had been preserved from Greek and Roman times were recognized as being purely products of art, but in medieval and later times the idea of the magic quality of all engraved gems had become so deeply rooted that in many cases a magical character was ascribed to them entirely foreign to the intention of the engraver. Great ingenuity was often displayed in seeking and finding some analogy between the supposed significance of the design and the fancied power of the stone itself. Taking the agate as an illustration, Camillo Leonardo says that its many different varieties had as many different virtues, and he finds in this an explanation of the multiplicity of images engraved on the various kinds of agate, without realizing that the true reason was that this material lent itself more readily to artistic treatment than did many others. The idea that some special design should be engraved upon a given stone became quite general in the early centuries of our era. The emerald, for instance, according to Damigeron, was to be engraved with a scarab, beneath which was to be a standing figure of Isis. The gem, when completed, was to be pierced longitudinally and worn in a brooch. The fortunate owner of this talisman was then to adorn himself and the members of his family, and, a consecration having been pronounced, he was assured that he would see “the glory of the stone granted it by God.”[190] Possibly this may have meant that the stone would become luminous. A list of these symbolic designs is said to have been given in the “Book of Wings,” by Ragiel, one of the curious treatises composed about the thirteenth century under the influence of Hebrew and Greco-Roman tradition. Although it owes its origin to the Hebrew “Book of Raziel,” it bears little if any likeness to that work. As will be seen in the following items, the fact that the design is on its appropriate stone is always insisted on: [Illustration: MOSS AGATE MOCHA STONES, HINDOOSTAN.] The beautiful and terrible figure of a dragon. If this is found on a ruby or any other stone of similar nature and virtue, it has the power to augment the goods of this world and makes the wearer joyous and healthy. The figure of a falcon, if on a topaz, helps to acquire the goodwill of kings, princes, and magnates. The image of an astrolabe, if on a sapphire, has power to increase wealth and enables the wearer to predict the future. The well-formed image of a lion, if engraved on a garnet, will protect and preserve honors and health, cures the wearer of all diseases, brings him honors, and guards him from all perils in travelling. An ass, if represented on a chrysolite, will give power to prognosticate and predict the future.