PRELUDE TO THE EPOCH OF COPERNICUS. 257 



might be represented by obvious modifications of those theories. I 

 speak of new Inequalities, new Phenomena, such as Copernicus, Gali- 

 leo, and Tycho Brahe discovered. As, however, these were very soon 

 referred to the Copernican rather than the Ptolemaic hypothesis, they 

 may be considered as developments 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. 



CHAPTER I. 



Pkelude to the Inductive Epoch of Copernicus. 



rTIHE Doctrine of Copernicus, that the Sun is the true centre of the 

 J- celestial motions, depends primarily upon the consideration that 

 such a supposition explains very simply and completely all the obvious 

 appearances of the heavens. In order to see that it does this, nothing 

 more is requisite than a distinct conception of the nature of Relative 

 Motion, and a knowledge of the principal Astronomical Phenomena. 

 There was, therefore, no reason why such a doctrine might not be dis- 

 covered, that is, suggested as a theory plausible at first sight, long be- 

 fore the time of Copernicus ; or rather, it was impossible that this 

 guess, among others, should not be propounded as a solution of the 

 appearances of the heavens. We are not, therefore, to be surprised if 

 we find, in the earliest times of Astronomy, and at various succeeding 

 periods, such a system spoken of by astronomers, and maintained by 

 some as true, though rejected by the majority, and by the principal 

 writers. 



When we look back at such a difference of opinion, having in our 

 minds, as we unavoidably have, the clear and irresistible considerations 

 by which the Copernican Doctrine is established for us, it is difficult 

 for us not to attribute superior sagacity and candor to those who held 

 that side of the question, and to imagine those who clung to the Ptol- 

 emaic Hypothesis to have been blind and prejudiced; incapable of 

 seeing the beauty of simplicity and symmetry, or indisposed to resign 

 established errors, and to accept novel and comprehensive truths. Yet 

 in judging thus, we are probably ourselves influenced by prejudices 

 arising from the knowledge and received opinions of our own times. 

 For is it, in reality, clear that, before the time of Copernicus, the Helio- 

 Vol. I.— 17 



