PT. i. Astronomy and Geology compared. 25 



like the Sun itself, by their own light, and are, in 

 fact, also suns. Should the calculations of Professor 

 Stokes be confirmed and the distances of the fixed 

 stars ascertained, these discoveries would only con- 

 firm what we possess a negative knowledge of 

 already that these stars are infinitely remote. The 

 same observation, however, would not apply to the 

 fact, if established, that the stars are not fixed, but 

 moved. Such a result would induce the belief, 

 either that they wandered about in space without 

 any guiding law, or that they were governed by 

 some more comprehensive system of which we only 

 could reach a part. 



We now approach the consideration of an essen- 

 tial difference of vast importance between these two 

 sciences. The magnitude of the consequences in- 

 volved in this difference it is impossible to estimate. 

 The distinction upon which I am about to remark is 

 no less than that of an absolute and entire difference 

 between the main principles of astronomical and 

 geological science. The Solar System is governed 

 by a law of fixity ; by which I mean, of course, not 

 that the bodies which compose it are stationary, but 

 that all their motions and the revolutions which 

 they make round the Sun as a common centre are 



