VESALIUS AND THE NEW ANATOMY 25 



During the four years that followed the issue of this 

 guide he had ample opportunities to dissect. He spent 

 all the time he could spare from teaching in the prepara- 

 tion of his great work on anatomy and physiology. It 

 was printed in 1543 in a magnificent and beautifully 

 illustrated large folio volume under the title The Fabric 

 of the Human Body. This work is one of the landmarks 

 in the history of science. The Fabric of the Human 

 Body is the first great work of anatomy or physiology 

 since the time of Galen. It is, for its time, a wonder- 

 fully full record of a prodigious number of accurately 

 recorded discoveries and investigations made by a single 

 observer. 



After the issue of his students' guide of 1538, Vesalius 

 had found that Galen and Aristotle were by no means 

 always to be trusted. This discovery led him to doubt 

 constantly any statement of Galen or Aristotle. His 

 scepticism was sometimes excessive, for Galen and 

 Aristotle were excellent observers. These doubts, how- 

 ever, led Vesalius to put every statement made by his 

 predecessors to the actual test of experience, and this 

 gave his work an epoch-making value. 



When Vesalius came to investigate the heart he was 

 in a peculiar difficulty. All the physiology of his time 

 was based on the view of Galen, which necessitated a 

 belief in the passage of blood from the right ventricle 

 to the left through the pores of the septum and a belief 

 that air entered the heart through the venal artery (our 

 pulmonary vein). To cast doubts on this without ex- 

 plaining the action of the heart would be to upset the 

 whole of the current notions of the workings of the human 

 body without putting anything in its place. This 

 Vesalius hesitated to do, and, although he hinted in his 

 book that the passages through the septum have no real 

 existence, yet he did not at first say so outright. 



