56 CIRCULATION OF THE BLOOD 



deep, and respect for antiquity influences all men. ... I 

 had long considered what was the quantity of blood 

 transmitted, and in how short a time its passage might 

 be effected. I did not find it possible that it could be 

 supplied by the juices of the ingested food . . . unless the 

 blood should somehow find its way from the arteries into 

 the veins, and so return to the right side of the heart." 



' I now began to think whether there might not be 

 A MOVEMENT, AS IT WERE, IN A CIRCLE, and this I after- 

 wards found to be true. I saw that the blood, forced 

 by the action of the left ventricle into the arteries, was 

 distributed to the body at large, and its several parts. In 

 the same manner it is sent through the lungs, impelled by 

 the right ventricle into the arterial vein [pulmonary artery] . ' ' 



It is very strange that in the midst of this, his great 

 discovery, he should return again to the Aristotelian 

 position. But so it is ! He continues his reflections in 

 words which might almost be quoted from Aristotle, 

 or rather from a mediaeval interpretation of Aristotle. 



The heart then is the beginning of life ; the Sun of the 

 Microcosm [that is of the human body] , even as the Sun 

 may be called the heart of the world. It is the heart 

 by whose virtue and pulse the blood is moved, perfected, 

 and made nutrient, and preserved from corruption and 

 coagulation. The heart is the Lar [that is, the god of 

 the hearth] which, discharging its function, nourishes, 

 cherishes, quickens the whole body. The heart is the 

 foundation of life, the source of all action." 



12. Here he comes now to a conclusion which is best 

 stated in his own words : 



' And now the cause is manifest, why in our dissec- 

 tions we usually find so large a quantity of blood in 

 the veins, so little in the arteries ; why there is much 

 in the right ventricle, so little in the left, which prob- 

 ably led the ancients to believe that the arteries con- 



