Many engraved stones of the Roman imperial period bore the figures of Serapis and of Isis, the former signifying Time and the latter Earth. On other stones the symbols of the zodiacal signs appear, referring to the natal constellation of the wearer. The astrologers, who derived their lore from the Orient, were consulted by all classes of the Roman people, and it is therefore very natural that the signet, or the ring worn as an amulet, should frequently have been engraved with astrological symbols. These designs were usually engraved on onyxes, carnelians, and similar stones, in Greek and Roman times; but occasionally the emerald was used in this way, and more rarely the ruby or the sapphire. Here the costliness of the material was probably thought to enhance the value of the amulet. The emerald ring of Polycrates must have possessed some other than a purely artistic value in his eyes, when it could be regarded by him as the most precious of his possessions. In Roman times the image of Alexander the Great was looked upon as possessing magic virtues, and it is related that when Cornelius Macer gave a splendid banquet in the temple of Hercules, the chief ornament of the table was an amber cup, in the midst of which was a portrait of Alexander, and around this his whole history figured in small, finely engraved representations. From this cup Macer drank to the health of the pontifex and then ordered that it should be passed around among the guests, so that each one might gaze upon the image of the great man. Pollio, relating this, states that it was a common belief that everything happened fortunately for those who bore with them Alexander’s portrait executed in gold or silver.[183] Indeed, even among Christians coins of Alexander were in great favor as amulets, and the stern John Chrysostom sharply rebukes those who wore bronze coins of this monarch attached to their heads and their feet.[184] Nowhere in the world was the use of amulets so common as in Alexandria, especially in the first centuries of our era, and the types produced here were scattered far and wide throughout the Roman world. Amulets made from various colored stones had been used for religious purposes in Egypt from the very earliest period of its history, so that the custom was deeply rooted in that land. When, therefore, Alexandria was founded in the fourth century B.C., and became a great commercial centre, attracting men of all races and all religions, it is not surprising that the population eagerly adopted the various amulets used by the adherents of the different religions. The result was a combining and confusion of many different types. With the rapid rise and growth of the Christian religion, a new element was introduced. Unquestionably the leading Christian teachers were strongly opposed to such superstitious practices, but the rank and file of the faithful clung to their old fancies.