Medicine · a Light

He corrected Galen on the heart and was lost for centuries

Around 1242, in Cairo, the Syrian physician Ibn al-Nafis wrote a commentary on the anatomy in Ibn Sina's Canon and disagreed with both Ibn Sina and Galen. The accepted view was that blood passed from the right side of the heart to the left through invisible pores in the wall between them. Ibn al-Nafis wrote that the wall is solid, with no pores, and that the blood must travel from the right chamber to the lungs, mix with air there, and return to the left. That is the pulmonary circulation, described three centuries before European anatomists. His text sat unread until a physician, Muhyi al-Din al-Tatawi, found it in a Berlin manuscript and published on it in 1924.

Ibn al-Nafis · Cairo, c. 1242 CE