Who was he?
ʿAlāʾ al-Dīn Abū al-Ḥasan ʿAlī ibn Abī al-Ḥazm al-Qurashī al-Dimashqī was born in or near Damascus in 1213 and trained at the Nūrī hospital (bīmāristān). According to respiratory physiologist John B. West (Journal of Applied Physiology, 2008), he moved to Cairo at 23, worked at the Nāṣirī and then the Manṣūrī hospital, and became physician-in-chief. The Annals of Saudi Medicine (2007) notes that he left his house and library to the Manṣūrī hospital, founded in 1284, and that he died in Cairo in December 1288.
The book
His key work is the Commentary on Anatomy in Avicenna’s Canon (Sharḥ Tashrīḥ al-Qānūn), published when he was about 29 (c. 1242). He also began an enormous medical encyclopaedia, al-Shāmil, never completed, which West calls the largest attempted in its time, and wrote al-Mūjaz, an abridgement of the Canon that was printed many times.
What Galen taught
In the Galenic model dominant since the second century, some blood went to the lungs to nourish them, while some passed from right to left ventricle through invisible pores in the interventricular septum, mixing with air in the left ventricle to form the “vital spirit”. Nobody had seen the pores; the model needed them anyway.
Three bold steps
West summarises three advances. First, Ibn al-Nafīs stated flatly that the septum is solid, with no passage, visible or invisible. Second, it followed that blood from the right ventricle reaches the left only through the lungs — the pulmonary (lesser) circulation. Third, he held that there must be small openings between the pulmonary artery and vein, a prediction that preceded Malpighi’s discovery of pulmonary capillaries by about 400 years.
Why it was overlooked
His description stayed unknown to European historians until the twentieth century, when the manuscript was found and studied. Western textbooks long credited the pulmonary circulation to Servetus and Colombo in the sixteenth century, before William Harvey (1578–1657) described the full circulation. To be fair: Ibn al-Nafīs described the lesser circulation, not the systemic circulation Harvey demonstrated.
Weekly exercise
Draw a four-chambered heart and trace the blood twice: once Galen’s way (through septal pores), once Ibn al-Nafīs’s way (through the lungs). Which drawing needs something nobody has observed? That is the difference between a comfortable model and one forced by observation.
Further reading
Reference links for verification. This article is original Vemetto wording and does not copy source text.