106 WILLIAM HARVEY 



the eyes, with their lustrous and truly admirable struc- 

 ture, or the flesh of the heart itself, which is more suitably 

 nourished by the coronary artery. 



CHAPTER VIII 



OF THE QUANTITY OF BLOOD PASSING THROUGH THE HEART 

 FROM THE VEINS TO THE ARTERIES; AND OF THE ClR- 

 CULAR MOTION OF THE BLOOD 



THUS far I have spoken of the passage of the blood 

 from the veins into the arteries, and of the manner in 

 which it is transmitted and distributed by the action of the 

 heart; points to which some, moved either by the authority 

 of Galen or Columbus, or the reasonings of others, will 

 give in their adhesion. But what remains to be said 

 upon the quantity and source of the blood which thus 

 passes is of a character so novel and unheard-of that I 

 not only fear injury to myself from the envy of a few, 

 but I tremble lest I have mankind at large for my enemies, 

 so much doth wont and custom become a second nature. 

 Doctrine once sown strikes deep its root, and respect for 

 antiquity influences all men. Still the die is cast, and my 

 trust is in my love of truth and the candour of cultivated 

 minds. And sooth to say, when I surveyed my mass of evi- 

 dence, whether derived from vivisections, and my various re- 

 flections on them, or from the study of the ventricles of the 

 heart and the vessels that enter into and issue from them, the 

 symmetry and size of these conduits, for nature doing 

 nothing in vain, would never have given them so large a 

 relative size without a purpose, or from observing the 

 arrangement and intimate structure of the valves in par- 

 ticular, and of the other parts of the heart in general, 

 with many things besides, I frequently and seriously be- 

 thought me, and long revolved in my mind, what might 

 be the quantity of blood which was transmitted, in how 

 short a time its passage might be effected, and the like. 

 But not finding it possible that this could be supplied by 

 the juices of the ingested aliment without the veins on 

 the one hand becoming drained, and the arteries on the 





