Al-Rāzī (Rhazes)

The first chemist to write a taxonomy — and the first major alchemist to publicly call transmutation a fraud.

In Kitāb al-Asrār ("The Book of Secrets"), al-Rāzī organized known substances into mineral, vegetable, animal, and derived classes — the first systematic chemical taxonomy. He also catalogued lab apparatus in detail and wrote the first surviving hospital case-record collection in his medical work. He reportedly performed transmutation demonstrations early in his career; he stopped, and his later writings are skeptical of the spiritual claims his peers were making. Taxonomy and clinical recordkeeping survived. The spiritual alchemy he turned away from did not.