HARVEY'S WORK 55 



is a continuous process, a growth, and can exist only as 

 growth. It is often the mark of genius that the meaning 

 of a phrase is fuller and deeper than even its author is 

 aware. Each investigator, too, must of necessity build 

 on the work of those who came before him, so that no 

 discovery is in a strict sense entirely new. It is the 

 demonstration of this process of growth or continuity, 

 and the discovery of the deeper meanings underlying 

 works of genius, that give its chief interest and charm to 

 the history of science. 



Harvey's respect for Galen is thus a form perhaps 

 some of his readers may think it becomes a rather 

 tiresome form of the humility and modesty that has 

 characterised most great discoverers. He goes on attri- 

 buting to Galen what is effectively his own discovery : 



The heart then is continually receiving and expelling 

 blood by and from its ventricle, and for this end is equipped 

 with four sets of valves two for the expulsion of blood 

 and two for its admission. ... As then the blood is 

 continually flowing into the right side of the heart and 

 flowing out of the left side of the heart, it is obvious 

 that it must somehow pass from the vena cava into the 

 aorta. ... It thus clearly appears that the blood must 

 penetrate through the porosities of the lung from the 

 right to the left ventricle [to get] from the vena cava to 

 the aorta." 



(b) THE SOLUTION 



ii. Here the author pauses and makes some interest- 

 ing reflections. 



What is now to be said on the quantity and source 

 of the blood which thus passes, is so novel and unheard- 

 off that I ... tremble lest I have mankind at large for 

 my opponents, so much doth wont and custom become 

 a second nature. Doctrine, once sown, strikes its root 



