Muhammad ibn Zakariya al-Razi

Muhammad ibn Zakariya al-Razi was born around 865 CE in Ray, Persia (near modern Tehran). Legend holds he came to medicine late, after first pursuing alchemy and music, but once committed, he became the most influential clinician of the Islamic Golden Age. He directed hospitals in Ray and later in Baghdad, where he reportedly selected the hospital site by scientific method: hanging pieces of meat throughout the city and choosing the location where decay was slowest. His Al-Hawi (The Comprehensive Book) was a massive medical encyclopedia, twenty-three volumes gathering Greek, Persian, Indian, and Arabic medical knowledge alongside his own clinical observations. It was translated into Latin as 'Liber Continens' and used in European medical schools for centuries. His treatise on smallpox and measles was the first to clinically differentiate the two diseases, a landmark in diagnostic medicine.