The medieval physician who dismantled Galen's anatomy centuries before modern science caught up

Ideas & Philosophy · Published 29 September 2026 Swipe more like this →

In short: Ibn al-Nafis, a 13th-century polymath, shattered the medical consensus of his time by proving the heart's septum was solid. By rejecting the long-held belief in invisible pores, he correctly identified pulmonary circulation, mapping how blood travels through the lungs to reach the left side of the heart.

Born in Damascus between 1210 and 1213, Ibn al-Nafis was a polymath whose expertise spanned medicine, jurisprudence, and theology. His most influential work, 'Commentary on Anatomy in Avicenna's Canon', was published when he was just 29. In this text, he displayed a rare boldness, challenging the established Greco-Roman medical authorities, specifically Galen and Avicenna, who had dominated the field for centuries.

Galen’s theory, which remained unchallenged for over a millennium, posited that blood reached the left side of the heart through invisible pores in the cardiac septum. Ibn al-Nafis rejected this entirely, noting that the septum is thick and solid. Through his own observations and animal dissections, he proposed that blood instead flows from the right ventricle into the lungs via the pulmonary artery, mixes with air, and returns to the left ventricle through the pulmonary vein. He even predicted the existence of small communications between these vessels, an insight into capillary circulation that preceded its formal discovery by over 400 years.

Beyond his anatomical breakthroughs, Ibn al-Nafis was a prolific writer, planning a 300-volume medical encyclopedia titled 'Al-Shamil fi al-Tibb', of which he completed 80 volumes before his death in Cairo. He served as chief physician at hospitals founded by Saladin and later Sultan Qalawun. Despite his immense contributions, his work remained largely unknown to the West until 1924, when physician Muhyo Al-Deen Altawi discovered his commentary in a Berlin library, finally revealing the depth of his physiological insights to the modern world.

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