Entertainment / Literature / Alchemy: The medieval and Renaissance precursor to modern chemistry, characterized by mystical philosophy and attempts to turn 'base' metals such as lead and tin into 'noble' metals such as gold and silver. The tenets of alchemy were based on the theory of the four elements (see elements, the four), in which all matter was composed of varying proportions of four substances--air, earth, water, and fire. Each element had a corresponding type of spirit associated with it--sylphs, gnomes, undines, and salamanders. While alchemical beliefs were taken seriously as a matter of pseudo-scientifical inquiry in early centuries, by the end of the medieval period, the practice was often synonymous with chicanery and con-artistry. Chaucer's 'Canon Yeoman's Tale' focuses on the deceptions of false alchemical practitioners, and Shakespeare's The Tempest borrows heavily from alchemical lore in its depiction of the island's magical spirits. In later, more enlightened times, alchemical beliefs became a subject of mockery. Alexander Pope's mock epic, The Rape of the Lock, employs the traditional alchemical spirits, but alters their purpose so that their primary duties involve protecting young girls' virginity from the advances of handsome rakes, for instance.