Muhammad ibn Zakariya al-Razi

Born around 864 or 865 CE during the Islamic Golden Age, Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī worked as physician, philosopher, and alchemist across Persia, eventually rising to chief physician at the hospitals of Baghdad and Ray. An early champion of experimental medicine, he attracted students from all backgrounds and treated rich and poor patients with equal care. Alongside Thābit ibn Qurra, he made the clinical distinction between smallpox and measles; he also advanced pediatrics, obstetrics, and ophthalmology, and critiqued religious concepts like prophethood - though those writings survive only in fragments, often preserved by hostile sources. His sprawling medical treatise Al-Mansuri became required reading in Western universities after translation, its surgery and therapy volumes folding into the European curriculum. Edward Granville Browne called him "probably the greatest and most original of all the Muslim physicians." He died sometime between 925 and 935, leaving a body of work that redirected medicine on two continents.