192 COSMICAL ARRANGEMENTS. 



often treated by means of abstract conceptions 

 and d priori reasonings ; and was sometimes con- 

 sidered as one in which the result of the struggle 

 between rival systems of philosophy, the Car- 

 tesian and Newtonian for instance, was involved. 

 It was conceived by some that the Newtonian 

 doctrine of the motions of the heavenly bodies, 

 according to mechanical laws, required that the 

 space in which they moved should be, absolutely 

 and metaphysically speaking, a vacuum. 



This, however, is not necessary to the truth of 

 the Newtonian doctrines, and does not appear to 

 have been intended to be asserted by Newton 

 himself. Undoubtedly, according to his theory, 

 the motions of the heavenly bodies were calcu- 

 lated on the supposition that they do move in a 

 space void of any resisting fluid ; and the compa- 

 rison of the places so calculated with the places 

 actually observed, (continued for a long course of 

 years, and tried in innumerable cases,) did not 

 show any difference which implied the existence 

 of a resisting fluid. The Newtonian, therefore, 

 was justified in asserting that either there was no 

 such fluid, or that it was so thin and rarefied, 

 that no phenomenon yet examined by astrono- 

 mers was capable of betraying its effects. 



This was all that the Newtonian needed or 

 ought to maintain ; for his philosophy, founded 

 altogether upon observation, had nothing to do 

 with abstract possibilities and metaphysical ne- 



