WILLIAM HARVEY, M. D. 67 



which receive light from the truth I have been contending for, 

 and which, in turn, render it more obvious. And indeed I would 

 have it confirmed {firmatain) and beautified {exorriatam) by 

 anatomical arguments above all others." °" 



This chapter is primarily an elaboration of the formal cause 

 of the heart through the re-examination of the heart and the 

 vessels — structurally, comparatively, embryologically and func- 

 tionally — in the light of the final cause, viz. the circulation of 

 the blood. His final statement which closes his treatise is: " it 

 would be difficult to explain in any other way for what cause all 

 is constructed and arranged as we have seen it to be." 



He establishes what a heart is in his characterization of the 

 heart per se as the left ventricle, viz. that ventricle " distin- 

 guished by use not position, the one namely that distributes 

 blood to the body at large, not the lungs alone." In doing so he 

 establishes the connection of the final and formal causes. 



This chapter completes the definition of the heart for 

 Harvey, which definition may be expressed in syllogistic form 

 as follows: 



An organ which must supply an organ which is so con- 



the body with a steady flow structed as to be able to 



of a fluid whose quantity is produce a circular motion 



proportionately small is of that fluid. 



And the heart has this very function. 



Therefore the heart is: 



1 . An organ which has a pulsating " left " ventricle mth a 

 non-regurgitating valvular inlet and outlet and whatever addi- 

 tional cardiac parts that conform to the needs of the species 

 (the formal cause: the anatomical structure described teleo- 

 logically and in detail, i.e., in its relationship to its motion, 

 pulse, action, use and utilities, e. g., the arrangement of the 

 fibres in the walls, the valves, the braces of the heart; " the 

 actions and uses of the heart may be understood from the con- 



^^ Harvey, Works, op. cit., ch. 16, p. 74. 



