140 DISCOVERY CH. 



was rationally sceptical and critical of so-called facts, 

 and was always ready to put them and principles to 

 the test of experiment. 



The principles of our art are not less necessary to be under- 

 stood than the principles of other sciences ; unless, indeed, the 

 surgeon should wish to resemble the Chinese philosopher whose 

 knowledge consisted only in facts. In that case, the science 

 must remain unimproved until new facts arise. In Europe, 

 philosophers reason from principles and thus account for facts 

 before they arise. John Hunter. 



On one occasion there was a discussion at a meeting 

 at which Hunter was present as to the structure of 

 certain organs in the digestive system of birds. The 

 meeting adjourned without settling the question, and 

 on the next assembly quotations from the works of 

 Aristotle, Hippocrates, Galen and other authorities 

 were brought forward by the advocates of particular 

 views in support of their opinions. Hunter had not gone 

 to the early masters for confirmation, but had dissected 

 the organs and exhibited them on a plate. All the 

 books in the world and all the speculations of philo- 

 sophers throughout the ages are but feather-weights 

 in comparison with ocular evidence of this kind. 



The desire to test and measure for himself instead 

 of accepting the observations and systems of ancient 

 astronomers as fixed standards of reference led to the 

 foundation of modern astronomy of precision by Tycho 

 Brahe (1546-1601). While a boy of thirteen at the 

 University of Copenhagen this young Danish noble 

 was impressed by the observation of a partial eclipse 

 of the sun, which had occurred punctual to prediction. 

 He then determined to train himself for an astronomer, 

 and when a youth of seventeen we find him making 

 measurements of a conjunction of the planets Jupiter and 



