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THE POPULAR SCIENCE MONTHLY 



scientific culture formed. Among the notable workers and thinkers of 

 the thirteenth and fourteenth centuries were Eoger Bacon (1214-1292) 

 in Cambridge and Paris, John Miiller of Konigsberg (1436-1476), and 

 Leonardo da Vinci (1452-1519), the artist philosopher of Florence. 

 In the early part of the sixteenth century the illustrious Copernicus ap- 

 pears (1473-1543). Copernicus, or Copernic, had a keen mind and a 

 firm belief in what may be called the simplicity of nature. On examin- 

 ing the Ptolemaic system he was embarrassed by its epicycles and ex- 

 centrics, producing, as they did, complexity where he believed there 

 should be simplicity. He, therefore, turned with relief to the ancient 

 ideas of Pythagoras, and of his system he says : 



The several appearances of the heavenly bodies will not only follow from 

 this hypothesis, but it will so connect the order of the planets, their orbits, 

 magnitudes and distances, and even the apparent motion of the fixed stars, that 

 it would be impossible to remove one of these bodies out of its place without 

 disordering the rest and even the whole universe also. 



Under the hand of Copernic this system was elaborated and shaped 

 so as to acquire a dignity equal to that of the older system, and, but 



