'Chemistry is the art of preparing gold and silver. The books concerning it were sought out and burnt by Diocletian, on account of the new plots directed against him by the Egyptians. He behaved towards them with great cruelty in his search after the treatises written by the ancients, his purpose being to prevent them from growing rich by a knowledge of this art, lest, emboldened by measureless wealth, they should be induced to resist the Roman supremacy.' Some authorities assert, however, that this art, or pretended art, is of much greater antiquity than Suidas knew of; and Scaliger refers to a Greek manuscript by Zozomen, of the fifth century, which is entitled 'A Faithful Description of the Secret and Divine Art of Making Gold and Silver.' We may assume that as soon as mankind had begun to set an artificial value upon these metals, and had acquired some knowledge of chemical elements, their combinations and permutations, they would entertain a desire to multiply them in measureless quantities. Dr. Shaw speaks of no fewer than eighty-nine ancient manuscripts, scattered through the European libraries, which are all occupied with 'the chemical art,' or 'the holy art,' or, as it is sometimes called, 'the philosopher's stone'; and a fair conclusion seems to be that 'between the fifth century and the taking of Constantinople in the fifteenth, the Greeks believed in the possibility of making gold and silver,' and called the supposed process, or processes, _chemistry_.