air to create spirit, and was then distributed to the body. According to Galen, the venous system was separate from the arterial system except when they came in contact through the unseen pores. The newly-discovered manuscript of Ibn al-Nafis was translated by Max Meyerhof. It included critiques of Galen's theory, including a discussion on the pores of the heart. Based on animal dissection, Galen hypothesized porosity in the septum in order for blood to travel within the heart as well as additional help on the part of the lungs. However, he could not observe these pores and so thought they were too small to see. “Ibn al-Nafīs's critiques were the result of two processes: an intensive theoretical study of medicine, physics, and theology in order to fully understand the nature of the living body and its soul; and an attempt to verify physiological claims through observation, including dissection of animals.” Ibn al-Nafis rejected Galen's theory in the following passage: The blood, after it has been refined in the right cavity, must be transmitted to the left cavity where the (vital) spirit is generated. But there is no passage between these cavities, for the substance of the heart is solid in this region and has neither a visible passage, as was thought by some persons, nor an invisible one which could have permitted the transmission of blood, as was alleged by Galen. He posited that the "pores" of the heart are closed, that there is no passage between the two chambers, and the substance of the heart is thick. Instead, Ibn al-Nafis hypothesized that blood rose into the lungs via the arterial vein and then circulated into the left cavity of the heart. He also believed that blood (spirit) and air passes from the lung to the left ventricle and not in the opposite direction. Some points that conflict with Ibn al-Nafis' are that there are only two ventricles instead of three (Aristotle's, 4th century BC) and that the ventricle gets its energy from the blood flowing in the vessels running in the coronary vessels, not from blood deposited in the right ventricle. Based on his anatomical knowledge, Ibn al-Nafis stated: Blood from the right chamber of the heart must arrive at the left chamber, but there is no direct pathway between them. The thick septum of the heart is not perforated and does not have visible pores as some people