CHAPTER I. 



PRELUDE TO THE INDUCTIVE EPOCH OF 

 COPERNICUS. 



THE Doctrine of Copernicus, that the Sun is 

 the true center of the celestial motions, de- 

 pends 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 prin- 

 cipal Astronomical Phenomena. There was, there- 

 fore, no reason why such a doctrine might not be 

 discovered, that is, suggested as a theory plausible 

 at first sight, long before 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 surprized 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 



