Muhammad ibn Zakariya al-Razi

Muhammad ibn Zakariya al-Razi (c. 854-925 CE), known in the Latin West as Rhazes, was a Persian physician, alchemist and philosopher who worked chiefly in Baghdad and Rayy, where he directed major hospitals. He is best known in medicine for his clinical treatise distinguishing smallpox from measles, one of the earliest such differential diagnoses in medical history, and for a vast medical encyclopedia, the Al-Hawi, that compiled and critically assessed the medical knowledge of his time. His works were translated into Latin and used as standard medical textbooks in European universities for centuries, and he is regarded as one of the most important physicians of the medieval Islamic world.