CHAPTER I 



THE AUTHOR'S MOTIVES FOR WRITING 



WHEN I first gave my mind to vivisections, as a means 

 of discovering the motions and uses of the heart, and 

 sought to discover these from actual inspection, and not 

 from Ihe writings of others, I found the task so truly 

 arduous, so full of difficulties, that I was almost tempted 

 to think, with Fracastorius, that the motion of the heart 

 was only to be comprehended by God. For I could 

 neither rightly perceive at first when the systole and 

 when the diastole took place, nor when and where 

 dilatation and contraction occurred, by reason of the 

 rapidity of the motion, which in many animals is 

 accomplished in the twinkling of an eye, coming and 

 going like a flash of lightning ; so that the systole pre- 

 sented itself to me now from this point, now from that ; 

 the diastole the same; and then everything was 

 reversed, the motions occurring, as it seemed, variously 

 and confusedly together. My mind was therefore 

 greatly unsettled, nor did I know what I should myself 

 conclude, nor what believe from others ; I was not 

 surprised that Andreas Laurentius should have said 

 that the motion of the heart was as perplexing as the 

 flux and reflux of Euripus had appeared to Aristotle. 



At length, and by using greater and daily diligence, 

 having frequent recourse to vivisections, employing a 

 variety of animals for the purpose, and collating 

 numerous observations, I thought that I had attained 

 to the truth, that I should extricate myself and escape 

 from this labyrinth, and that I had discovered what I so 

 much desired, both the motion and the use of the heart 

 and arteries ; since which time I have not hesitated to 



22 



