Ibn al-Nafis

Ala al-Din Abu al-Hasan Ali ibn Abi Hazm al-Qarshi al-Dimashqi — Ibn al-Nafis — was born in 1213 CE in Damascus. He received his early religious and linguistic education in the city's schools and madrasas before turning to medicine, which he studied at the prestigious Nuri Hospital under the master physician Muhadhdhab al-Din al-Dakhwar. The Nuri Hospital was a functioning institution of remarkable sophistication, combining clinical treatment with medical education, and Ibn al-Nafis absorbed both its practical and theoretical dimensions with exceptional ability.

Sometime in the mid-thirteenth century, Ibn al-Nafis moved to Cairo, where he would spend the rest of his life and achieve his greatest eminence. Cairo under the Mamluk Sultanate was the political and cultural capital of the eastern Arab world, and Ibn al-Nafis rose to become chief physician of the Mansuri Hospital — the largest hospital in the medieval world — and personal physician to the sultan Baybars. He combined a vast clinical practice with an equally vast literary output, writing commentaries on Ibn Sina's Canon of Medicine, original works on ophthalmology, diet, and embryology, a compendium of medicine called the Shamil (The Comprehensive), and works on logic and theology.

The discovery for which he is now celebrated came in a commentary on Ibn Sina's Canon written when he was still a relatively young physician. In this work, commenting on the anatomy of the heart, he contradicted both Galen and Ibn Sina — the two supreme authorities of medieval medicine — by denying that blood passes through pores in the interventricular septum, the wall between the heart's two ventricles. Galen had taught, and Ibn Sina had repeated, that blood seeps from the right ventricle to the left through invisible pores in this wall. Ibn al-Nafis stated flatly that the septum is solid and impermeable: "There is no passage between them," he wrote. He then described, for the first time in recorded history, the correct path that blood actually takes: from the right ventricle it flows to the lungs through the pulmonary artery, is mixed with air and purified in the lungs, and then returns to the left ventricle through the pulmonary vein. This is pulmonary circulation — the lesser circulation of the blood — discovered by Ibn al-Nafis three centuries before Michael Servetus described it in Europe in 1553 and four centuries before William Harvey formalized the complete theory of blood circulation in 1628.

Ibn al-Nafis's reasoning was partly observational — he noted that the septum has no visible pores even in fresh cadavers — and partly logical: the construction of the heart and its vessels made any other pathway impossible. He was also apparently guided by his refusal to simply repeat authoritative texts. He wrote that he relied "on rational proof and observation, not on the authority of Galen or Ibn Sina."

Beyond this landmark discovery, Ibn al-Nafis wrote the Shamil fi al-Tibb — the most comprehensive medical encyclopedia attempted in medieval Islam, reportedly running to three hundred volumes, of which he completed eighty before his death. He wrote on ophthalmology, the preservation of health, the pulse, and embryology. In theology and philosophy he wrote a remarkable allegorical novel, Risalat Fadil ibn Natiq (The Story of Theologus Autodidactus), a theological science-fiction narrative in which a human being is spontaneously generated on a desert island without parents and arrives independently at Islamic religious truth — a work that predates and echoes Daniel Defoe's Robinson Crusoe by more than four centuries.

In his personal character Ibn al-Nafis was known for piety, frugality, and generosity. He never married, lived simply, and on his deathbed donated his house, library, and all his possessions to the Mansuri Hospital. He died in Cairo in December 1288, aged seventy-four or seventy-five.

His discovery of pulmonary circulation remained largely unknown in Europe until 1924, when the Egyptian physician Muhyi al-Din al-Tatawi discovered a manuscript of the relevant commentary in the Prussian State Library in Berlin and published his findings. Until that point, the discovery had been attributed entirely to Servetus, Realdo Colombo, and Harvey. The rehabilitation of Ibn al-Nafis's priority was one of the most dramatic episodes in the history of medicine.