Abū Mūsā Jābir ibn Ḥayyān, died c. 806−816, is the purported author of an enormous number and variety of works in Arabic, often called the Jabirian corpus. The works that survive today mainly deal with alchemy and chemistry, magic, and Shi'ite religious philosophy. However, the original scope of the corpus was vast and diverse, covering a wide range of topics ranging from cosmology, astronomy and astrology, over medicine, pharmacology, zoology and botany, to metaphysics, logic, and grammar.
Jabir's works contain the oldest known systematic classification of chemical substances, and the oldest known instructions for deriving an inorganic compound from organic substances by chemical means. His works also contain one of the earliest known versions of the sulfur-mercury theory of metals, a mineralogical theory that would remain dominant until the 18th century.
A significant part of Jabir's writings were informed by a philosophical theory known as "the science of the balance", which was aimed at reducing all phenomena to a system of measures and quantitative proportions.