378 INTRODUCTION. 



became very soon an important and extensive 

 science; and in no long period, the discoveries of 

 Kepler, suggested by a vague but intense belief 

 in the physical connexion of the parts of the uni- 

 verse, led to the decisive and sublime generali- 

 zations of Newton. 



The distinction of formal and physical Astro- 

 nomy thus becomes necessary, in order to treat 

 clearly of the discussions which the propounding 

 of the Copernican theory occasioned. But it may 

 be observed that, besides this great change, Astro- 

 nomy made very great advances in the same path 

 which we have already been tracing, namely, the 

 determination of the quantities and laws of the 

 celestial motions, in so far as they were exhibited 

 by the ancient theories, or might be represented 

 by obvious modifications of those theories. I speak 

 of new Inequalities, new Phenomena, such as Co- 

 pernicus, Galileo, and Tycho Brahe discovered. As, 

 however, these were very soon referred to the 

 Copernican rather than the Ptolemaic hypothesis, 

 they may be considered as developements rather 

 of the new than of the old Theory ; and I shall, 

 therefore, treat of them, agreeably to the plan of 

 the former part, as the sequel of the Copernican 

 Induction. 



