Abu Bakr al-Razi
Abū Bakr al-Rāzī (full name: أبو بکر محمد بن زکریاء الرازي, Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī), c. 864 or 865–925 or 935 CE, often known as (al-)Razi or by his Latin name Rhazes, also rendered Rhasis, was a Persian physician, philosopher and alchemist who lived during the Islamic Golden Age. He is widely regarded as one of the most important figures in the history of medicine, and also wrote on logic, astronomy and grammar. He is also known for his criticism of religion, especially with regard to the concepts of prophethood and revelation. However, the religio-philosophical aspects of his thought, which also included a belief in five "eternal principles", are fragmentary and only reported by authors who were often hostile to him.

A comprehensive thinker, al-Razi made fundamental and enduring contributions to various fields, which he recorded in over 200 manuscripts, and is particularly remembered for numerous advances in medicine through his observations and discoveries. An early proponent of experimental medicine, he became a successful doctor, and served as chief physician of Baghdad and Ray hospitals. As a teacher of medicine, he attracted students of all backgrounds and interests and was said to be compassionate and devoted to the service of his patients, whether rich or poor. He was the first to clinically distinguish between smallpox and measles, and suggest sound treatment for the former.

Through translation, his medical works and ideas became known among medieval European practitioners and profoundly influenced medical education in the Latin West. Some volumes of his work Al-Mansuri, namely "On Surgery" and "A General Book on Therapy", became part of the medical curriculum in Western universities. Edward Granville Browne considers him as "probably the greatest and most original of all the Muslim physicians, and one of the most prolific as an author". Additionally, he has been described as the father of pediatrics, and a pioneer of obstetrics and ophthalmology.
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