Physician. Al-Nafis after acquiring his expertise in medicine and jurisprudence moved to Cairo where he was appointed as the Principal at the famous Nasri Hospital. He also served as the Dean at the Mansuriya School. Al-Nafis's contribution in medicine was of great significance in the discovery of the blood's circulatory system, which was re-discovered by modern science after a lapse of three centuries. He was the first to correctly describe the constitution of the lungs and gave a description of the bronchi and the interaction between the human body's vessels for air and blood. He further elaborated the function of the coronary arteries as feeding the cardiac muscle. Al-Nafis' most voluminous books 'Al-Shamil fi al-Tibb', an encyclopaedia comprising 300 volumes, which could not be completed due to his death, are available in manuscript in Damascus. His book that became famous was 'Mujaz al-Qanun' and 'Kitab al-Mukhtar fi al-Aghdhiya' on the effects of diet on health. Al-Nafis wrote several commentaries including on Hippocrates' book and, in 1286, on the anatomy of Ibn Sina's 'Qanun' (Avicenna's Canon) in which he described for the first time in the world of medicine the circulation of the blood through the lungs for the purpose of oxygenation. Ibn al-Nafis was born Ala-al-Din Abu al-Hasan Ali Ibn Abi al-Hazm al-Qarshi al-Damashqui al-Misri at Damascus. When he died he donated his house, library and clinic to the Mansuriya Hospital at Cairo.