Technology & Medicine › Medieval › Islamic Golden Age science and medicine
Ibn al-Nafis and the lung circulation
1242 (pulmonary circulation)· Person· Medicine & surgery
Well documentedSolid records, physical evidence or scientific consensus.
Arab physician in Cairo who in 1242 correctly described blood passing from the heart through the lungs, overturning Galen.
See it on the Technology & Medicine map →How it works
Born in Damascus in 1213, Ibn al-Nafis became a leading physician in Cairo. In a 1242 commentary on the anatomy in Ibn Sina's Canon, he argued that the wall between the heart's two lower chambers is solid, with none of the hidden pores Galen claimed. Blood must therefore travel from the right side through the lungs, mix with air, and return to the left side. He also wrote a large medical encyclopedia.
Why it mattered
He gave the first correct account of pulmonary (lung) circulation, about 300 years before Europeans; it was a key piece of the full circulation Harvey proved in 1628.
Legacy and how we know
His commentary, rediscovered in a Berlin library manuscript in 1924 by the Egyptian physician Muhyo al-Deen Altawi, plus other copies and medieval biographies.
Still unknown or debated
Whether he observed this by dissection or reasoned it out is debated, as is whether Servetus and Colombo, who described the same circuit in the 1550s, knew his work.
Connections (2)
▸Galen was corrected on the heart by Ibn al-Nafis and the lung circulationWell documented
The connection
Galen taught that blood seeped from the heart's right side to its left through invisible pores in the dividing wall (septum). Ibn al-Nafis, commenting on anatomy in 1242, said the septum is solid and impermeable, so blood must go from the right ventricle through the lungs to reach the left: the pulmonary circulation.
When and how
Cairo, about 1242, in his Commentary on the Anatomy of Ibn Sina's Canon.
How we know
His text explicitly rejects Galen's pores, stating the septum has no visible or invisible passage; manuscripts of it survive.
Debates and open questions
He wrote that religious law and compassion kept him from dissection, so whether his insight came from reasoning, animal dissection or unrecorded observation is debated.
▸Ibn al-Nafis and the lung circulation anticipated part of Harvey's discovery of blood circulationWell documented
The connection
Ibn al-Nafis, a physician in Cairo, argued in 1242 that blood cannot pass through the heart's thick middle wall, as Galen claimed, but must travel from the right side through the lungs to the left. That is the pulmonary, or lung, circuit: one half of the full circulation Harvey proved in 1628.
When and how
Cairo, in his commentary on Ibn Sina's Canon, written around 1242; similar ideas reappeared in Europe with Michael Servetus (1553) and Realdo Colombo (1559).
How we know
His manuscript, rediscovered in Berlin in 1924 by the Egyptian physician Muhyo Al-Deen Altawi, states the idea clearly; whether it reached Europe is uncertain.
Debates and open questions
Some historians suggest his ideas reached Padua through Andrea Alpago's 1547 Latin translations of some of his writings; others think Europeans rediscovered them independently.