First Available Description of Circulation) Ibn Al Nafis Original Manuscript and Translation

“And this is the right one of the two Cavities of the heart. If blood was to be “purified” in these cavities, it must pass to the left cavity where the “soul” is generated, but there are no passages between the two cavities. The mass of the heart here is dull and has no visible apertures, as some people wrongly thought. In fact, there are no invisible openings suitable for the passage of blood, either as Galen wrongly thought. The cavities of the heart in this region are sealed and its mass is thick. Therefore, if is necessary that blood to be “purified” it has to pass through the “ARTERIAL VEIN” to the lungs where it penetrates into its mass, mixes with air, and the better part of it is “purified”. It then passes into the “VENOUS ARTERY” to reach the left cavity of the heart.”