10 



THE BLOOD 



getting round from the arteries into the veins, 

 and so back to the right ventricle — I began to 

 think to myself whether the blood had a certain 

 movement, as in a circle — ccepi egomet mecum 

 cogitare, an motionem quandam quasi in circulo 

 haberet — which afterward I found was true." 



This vehement passage, which goes with a rush 

 like that of the blood itself, is a good example of 

 the width and depth of Harvey's work — how he 

 used all methods that were open to him. He lived 

 to fourscore years; "an old man," he says, "far 

 advanced in years, and occupied with other cares " : 

 and, near the end of his life, he told the Hon. Robert 

 Boyle that the arrangement of the valves of the 

 veins had given him his first idea of the circulation 

 of the blood : — 



" I remember that when I asked our famous 

 Harvey, in the only discourse I had with him, 

 which was but a while before he died, what were 

 the things which induced him to think of the 

 circulation of the blood, he answered me that 

 when he took notice that the valves in the veins 

 of so many parts of the body were so placed that 

 they gave free passage of the blood towards the 

 heart, but opposed the passage of the venal blood 

 the contrary way, he was invited to imagine that 

 so provident a cause as Nature had not so placed 

 so many valves without design ; and no design 

 seemed more probable than that, since the blood 

 could not well, because of the interposing valves, 

 be sent by the veins to the limbs, it should be 

 sent by the arteries, and return through the veins, 

 whose valves did not oppose its course that way." 



