Although the intellectual tendencies of the Hellenic mind were hardly calculated to favour the development of chemistry as a science, the speculations of the Greeks concerning the essential nature of matter and the mutual convertibility of the “elements” led incidentally to an extension of the art of operative chemistry. This extension resulted from attempts to realise what was the logical outcome of the teaching of their philosophers—viz., the possibility of the transmutation of metals. The idea of transmutation has its germ in the oldest systems of philosophy. It was a plausible doctrine, not wholly unsupported by the phenomena of the organic world; and it naturally commended itself to men who were only too prone to adopt what their cupidity and love of wealth predisposed them to believe. It has been assumed that alchemy at no time in its history had the slightest claim to a philosophical foundation, but that its professors and adepts, even at the outset, consciously traded on the credulity and greed of their dupes. Much may be urged against such a partial view. The supposition is not consistent with history or with evolutional tendencies. It may be, as Davy once said, that “analogy is the fruitful parent of error;” but the idea that metals could be modified—could even be changed one into the other—seemed to find support in innumerable chemical phenomena well known but imperfectly understood. The fact that alchemy—that is the profession of making gold from other metals—came to be practised by rogues is no proof that it never had, and never could have had, a philosophical basis.