An important source for the study of Hellenistic Alchemy is the Neoplatonic Olympiodorus and his treatise on “Sacred Art”. In this text Olympiodorus gives an unitary view of alchemical praxis, based on the production and transformation of a peculiar element, the so-called “magnet” or “magnesia”. This element is the “substantial body”, sōma hypostatikon, the body which is “giving existence”, the alchemical black lead, the prima materia. The alchemist succeeds, by his creative action, in obtaining a perfect body which is able to transmit perfection to every body with which it is in contact. This is the elixir which gives health and salvation. The processes described put emphasis on color change as a guide to progress from black to white to yellow to violet: the sequence was clearly associated with the change from a chaotic and undefined primal stage to metallic perfection. And although the final phase or iōsis was eventually to be changed from violet to red, the emphasis on color was to remain a basic theme in descriptions of the magnum opus.