may define the latter branch of knowledge as the science of transforming copper and brass into gold and silver. During the first two or three centuries of the Christian era there existed a firm belief that such a transformation had actually been accomplished, and in confirmation of the correctness of this statement it may be said that Zosimos of Panopolis, one of the leading philosophers of Alexandria during the fourth century of the present era, and a man who was considered by his contemporaries, as well as by all later alchemists, to be perhaps the greatest authority in this branch of knowledge, speaks in unmistakable terms in his cyclopaedic work on alchemy (28 volumes), of a certain tincture which possesses the power of changing silver into gold, and also of a "divine water" or fluid which is capable of effecting many different transmutations. There can therefore be no reasonable doubt that in the earlier centuries of the Middle Ages the learned men of Alexandria accepted alchemy as a well-established agency of great power. From the sixth century to the thirteenth this science was cultivated with great assiduity by the Arabs in the academies which they established in Cordova and other cities of Spain; and it was from the latter region that the belief in alchemy spread to all the countries of Western Europe, gradually gaining strength up to perhaps the fifteenth century.
It was during the thirteenth century that the so-called "philosophers' stone" came to be considered the most effective agent in transmuting the baser metals into silver and gold, and there were not a few who even believed that this as yet non-existent stone possessed the power to increase longevity, to confer health, and to give a prosperous issue to one's undertakings. It was not the rabble, but the very best and most highly educated men in the community who, during the thirteenth century, took the most active interest in alchemy and the philosophers' stone. Arnold of Villanova, Raymund Lullus, Roger Bacon, Albertus Magnus, and, to a lesser degree, the famous theologian Thomas Aquinas were all believers in the art of the magician. And even more extraordinary than this is the fact
