Medical advances are often made over long periods of time, making it difficult to assign priority to any particular individual. Such has been the case for the ”discovery” of the pulmonary circulation, a distinction variously assigned to three anatomists of the sixteenth century, Michael Servetus, Realdo Colombo, and Andrea Cesalpino. But in 1924 the Egyptian physician M. Altatawi cast a new light on the debate by rediscovering in a library in Berlin a manuscript written by an Arab physician known to the Western world by the abbreviated name of Ibn al-Nafis.

Born Syria in 1213, Ibn al-Nafis  studied medicine in Damascus before moving to Egypt in 1236 to teach jurisprudence in Cairo, then working at the Al-Mansouri Hospital and becomig chief physician and personal physician to the Sultan. He was a prolific author, writing on law, theology, philosophy, sociology, and astronomy; and in medicine he described the coronary circulation, the cranial nerves, and aspects of the anatomy of the gall bladder and of the eye. At the age of twenty-nine he published his “Commentary on the anatomy of the Canon of Avicenna”(Sharah al Tashreeh al Qanoon), the manuscript rediscovered in 1924 that makes him the front runner in terms of  who ”discovered” the pulmonary circulation. Though working in a country where dissections were not allowed, he somehow was able to make his anatomical observations.

Al-Nafis clearly rejected the long-held dogma of Galen that blood passed through the interventricular septum from the right ventricle to the left. There were no pores in the septum, he explained, but instead the path of the blood was through the pulmonary vasculature. Al-Nafis even postulated the existence of communications between the pulmonary artery and vein some four-hundred years before Malpighi described the existence of pulmonary capillaries. He also noted that the heart moves the blood by contracting not relaxing. It all seems so obvious nowadays, but it took many centuries to reach these conclusions.