Albinus See COMMENTARIES ON PLATO, MIDDLE. PLATONIS. alchemy, a quasi-scientific practice and mystical art, mainly ancient and medieval, that had two broad aims: to change baser metals into gold and to develop the elixir of life, the means to immortality. Classical Western alchemy probably originated in Egypt in the first three centuries A.D. (with earlier Chinese and later Islamic and Indian variants) and was practiced in earnest in Europe by such figures as Paracelsus and Newton until the eighteenth century. Western alchemy addressed concerns of practical metallurgy, but its philosophical significance derived from an early Greek theory of the relations among the basic elements and from a religious-allegorical understanding of the alchemical transmutation of ores into gold, an understanding that treats this process as a spiritual ascent from human toward divine perfection. The purification of crude ores (worldly matter) into gold (material perfection) was thought to require a transmuting agent, the philosopher’s stone, a mystical substance that, when mixed with alcohol and swallowed, was believed to produce immortality (spiritual perfection). The alchemical search for the philosopher’s stone, though abortive, resulted in the development of ultimately useful experimental tools (e.g., the steam pump) and methods (e.g., distillation). J.D.T.