Jabir ibn Hayyan

The Jabirian corpus, dated to roughly 850–950, covered everything from cosmology and medicine to logic and grammar, but its core was alchemy and the theory it called "the science of the balance" — an attempt to reduce all matter to measurable proportions. The works contain the oldest systematic classification of chemical substances and the sulfur-mercury theory of metals that dominated mineralogy into the eighteenth century. They also carried early Shi'ite theological doctrines, attributed to the Imam Jaʿfar al-Ṣādiq. By the tenth century, Islamic scholars already doubted whether a single hist…