INDUCTION OF COPERNICUS. 395 



perfection of the common theory ; arid he proposes 

 a new theory of the moon, for the very reason 

 which did at last overturn the doctrine of epicycles, 

 namely, that the ratio of their distances from the 

 earth at different times was inconsistent with the 

 circular hypothesis 5 . 



It is obvious, that, along with his mathematical 

 clearness of view, and his astronomical knowledge, 

 Copernicus must have had great intellectual bold- 

 ness and vigour, to conceive and fully develope a 

 theory so different as his was, from all received 

 doctrines. His pupil and expositor, Rheticus, says 

 to Schener, "I beg you to have this opinion con- 

 cerning that learned man, my Preceptor; that he 

 was an ardent admirer and follower of Ptolemy; 

 but when he was compelled by phenomena and 

 demonstration, he thought he did well to aim at 

 the same mark at which Ptolemy had aimed, though 

 with a bow and shafts of a very different material 

 from his. We must recollect what Ptolemy says, Aet 



c eXevOepov elvai rrj yvoa^ij TOV /ueXXoi/ra (pt\ocro(peii>. 



'He who is to follow philosophy must be a free- 

 man in mind.'" Rheticus then goes on to defend 

 his master from the charge of disrespect to the 

 ancients: "That temper," he says, "is alien from 

 the disposition of every good man, and most espe- 

 cially from the spirit of philosophy, and from no 

 one more utterly than from my Preceptor. He 

 5 De Rev. iv. c. 2. 



