A NEW ASTRONOMY 201 



nobody must expect certainty about astronomy, for it cannot give it ; 

 and whoever takes for truth what has been designed for a different 

 purpose, will leave this science as a greater fool than he was when 

 he approached it. 



INFLUENCE OF COPERNICUS. The publication of De Revoliir 

 tionibus was naturally a powerful stimulus to astronomical and 

 mathematical studies. Thus Rheticus, whose relations to Coper- 

 nicus had been so fruitful, calculated a new and extensive set 

 of mathematical tables, while Reinhold, who had hailed Coper- 

 nicus as a new Ptolemy, published astronomical tables the 

 Prutenic or Prussian on the basis of Copernicus' work, superior 

 to the Alfonsine, previously current. 



Before the new doctrine should be completely justified or the 

 reverse, it was necessary that certain mechanical notions should 

 be clarified, and that more accurate observational data should be 

 systematically collected. Copernicus had based his imposing \ 

 structure on a very slender foundation of actual fact, and had { 

 professed his complete satisfaction if his theoretical results should 

 come within ten minutes of the observed positions of the planets, 

 a degree of accuracy which he did not, in fact, attain. On the other 

 hand, he could indeed answer, but not rise entirely above, the 

 traditional notions that the four elements of the ancients must 

 have rectilinear, the heavenly bodies circular, motion ; also, that if 

 the earth rotated in twenty-four hours, loose bodies would long 

 since have been thrown off, falling bodies would not fall, and clouds 

 would always be left behind in the west. 



As suggested by Dreyer : 



It is interesting, though useless, to speculate on what would have 

 been the chances of immediate success of the work of Copernicus if 

 it had appeared fifty years earlier. Among the humanists there 

 certainly was considerable freedom of thought, and they would not 

 have been prejudiced against the new conception of the world because 

 it upset the medieval notion of a set of planetary spheres inside the 

 empyrean sphere, with places allotted for the hierarchy of angels. 

 If one of the leaders of the Church (at least in Italy) at the beginning 



