COPPERNICUS 165 



yet there is little in his work that could not have been, and 

 probably was not known to Ptolemy and Hipparchus. His in- 

 struments were, of course, the same ; he had his unaided eyes 

 to see with, as did they nothing more. He can hardly be 

 said to have made any great discovery possibly one ; nor did 

 he bring forward many new and decisive facts. He met objec- 

 tions to his theory in the same way that Aristarchus had ; his 

 arguments were the same. He can estimate no better the 

 distance or the grandeur of the sun, the moon, or the stars. 



This seems rather sweeping and assuredly caviare to the 

 general view. In most popular accounts you will find it stated 

 that " Coppernicus did not merely speculate, he proved " that 

 the earth was a planet like the rest, and revolves about the 

 sun. The general opinion of astronomers is otherwise. We 

 have it in the words of the learned Schiaparelli that 



" The two systems (the Ptolemaic, which reigned so long, 

 and the Coppernican) could be adapted to represent the pheno- 

 mena of the heavens equally well ; geometrically, they were 

 equivalent between themselves, and likewise to the system of 

 Tycho. Even Kepler, with his ellipses, was not able to over- 

 come the possibility of sustaining the immobility of the earth. 

 It was only Galileo and Newton who, setting out from physical 

 principles better grounded than those up to that time dominant 

 in the schools, were able finally to overturn it." * 



In truth, the absolute demonstration did not come until the 

 middle of the nineteenth century. Why, then, does the work 

 of Coppernicus in some sense mark an epoch in the history of 

 human ideas ? 



First of all, because it turned out to be the truth, to portray 

 the unbelievable reality ; but as much more because it is among 

 the highest products of the imaginative faculty. You will read 

 in many a place that Coppernicus was not a great and original 

 genius, in the sense that Newton and Darwin were. With all 

 that he borrows from Ptolemy, a careful study of his work 

 assuredly gives one a different impression. Consider that he 

 lived in an age when astronomy and astrology had not parted 

 company, and that amid all the wild fancies then prevalent 

 you find it a sane and modern work. Very often its mode of 

 reasoning is not satisfying ; you meet at times with the same 

 empty verbal explanations, as that the earth is round " because 

 1 I Precursor! di Copernico nelV Antichita, Milano, 1873. 



