F1, known in the West as Rhazes, was born in al-Rayy outside Tehran. He is considered one of the greatest physicians Islam has ever produced. He traveled widely, visiting famous medical centers of his time in Jerusalem, Cairo, and Cordova. In 907 he was appointed director of a large hospital in Baghdad and a court physician as well. He wrote 237 books, of which 36 have survived. The most famous of his works is Liber Continens, a medical encyclopedia.