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50 DESCARTES. 



words, to that part of us which is distinct from the 

 body, and of which it has been said above that the 

 nature distinctively consists in thinking, functions 

 in which the animals void of Reason may be said 

 wholly to resemble us; but among which I could 

 not discover any of those that, as dependent on 

 thought alone, belong to us as men, while, on the 

 other hand, I did afterwards discover these as soon 

 as I supposed God to have created a Rational Soul, 

 and to have annexed it to this body in a particular 

 manner which I described. 



But, in order to show how I there handled this 

 matter, I mean here to give the explication of the 

 motion of the heart and arteries, which, as the first 

 and most general motion observed in animals, will 

 afford the means of readily determining what should 

 be thought of all the rest. And that there may be 

 less difficulty in understanding what I am about to 

 say on this subject, I advise those who are not versed 

 in Anatomy, before they commence the perusal of 

 these observations, to take the trouble of getting 

 dissected in their presence the heart of some large 

 animal possessed of lungs, (for this is throughout 

 sufficiently like the human,) and to have shewn to 

 them its two ventricles or cavities: in the first place, 

 that in the right side, with which correspond two 

 very ample tubes, viz., the hollow vein, (vena cava,) 

 which is the principal receptacle of the blood, and 

 the trunk of the tree, as it were, of which all the 

 other veins in the body are branches; and the 

 arterial vein, (vena arteriosa^] inappropriately so 

 denominated, since it is in truth only an artery, 



