Circulation of the Blood 167 



and general organ of sensation. But if by the word 

 heart the mere body of the heart, made up of its auricles 

 and ventricles, be understood, then I do not believe 

 that the heart is the fashioner of the blood ; neither do 

 I imagine that the blood has powers, properties, motion, 

 or heat, as the gift of the heart ; lastly, neither do I 

 admit that the cause of the systole and contraction is 

 the same as that of the diastole or dilatation, whether 

 in the arteries, auricles, or ventricles ; for I hold that 

 that part of the pulse which is designated the diastole 

 depends on another cause different from the systole, and 

 that it must always and everywhere precede any systole ; 

 I hold that the innate heat is the first cause of dilata- 

 tion, and that the primary dilatation is in the blood 

 itself, after the manner of bodies in a state of fermenta- 

 tion, gradually attenuated and swelling, and that in the 

 blood is this finally extinguished ; I assent to Aristotle's 

 example of gruel or milk upon the fire, to this extent, 

 that the rising and falling of the blood does not depend 

 upon vapours or exhalations, or spirits, or anything 

 rising in a vaporous or aereal shape, nor upon any 

 external agency, but upon an internal principle under 

 the control of nature. 



Nor is the heart, as some imagine, anything like a 

 chauffer or fire, or heated kettle, and so the source of 

 the heat of the blood ; the blood, instead of receiving, 

 rather gives heat to the heart, as it does to all the 

 other parts of the body ; for the blood is the hottest 

 element in the body ; and it is on this account that the 

 heart is furnished with coronary arteries and veins ; it 

 is for the same reason that other parts have vessels, 

 viz. to secure the access of warmth for their due con- 

 servation and stimulation ; so that the warmer any part 

 is, the greater is its supply of blood, or otherwise ; 

 where the blood is in largest quantity, there also is the 

 heat highest. For this reason is the heart, remarkable 

 through its cavities, to be viewed as the elaboratory, 

 fountain, and perennial focus of heat, and as com- 



