320 ANTIENT METAPHYSICS. Book V. 



nite number of fides *, always increafing in number and decreafing 

 in length, till at laft they become evanefcent, as he exprefles it ; 

 and, if it can be fo analyfed, it muft be fo compounded. 



From this account of Sir Ifaac's Syftem, I think, it is evident, and, 

 indeed, it is admitted by all his followers, that he underftood the 

 Motion of iheCeleftial Bodies to be actually compounded of a tenden- 

 cy to go on in a Straight Line, and a tendency towards the Centre ;. 

 or, as he exprefTed it, of a Centrifugal and a. Centripetal Force ; or, 

 as it is more commonly exprefled, of Proje£lion and Gravitation. 



2^0, Further, I am of opinion that Sir Ifaac, when he wrote his 

 Principia, believed that both Motions were produced by bodily im- 

 pulfe ; for, though Sir Ifaac was undoubtedly a Theifl, and therefore 

 believed that God was ultimately the Author of all Motion in the 

 univerfe, yet he appears to have thought that the Motions of this our 

 Syftem were produced immediately by Bodily Impulfe, and car- 

 ried on by Matter and Mechanifm merely, without the inter- 

 vention of the Supreme Mind, or of any other. And, as this 

 Mechanical Motion was to continue forever, or for a very 

 long time, without the immediate adtion of any Power, whe- 

 ther of Body or Mind, he has fet out with eftablifhing, by his firft 

 axiom, the perpetuity of Motion once begun by a Vis Imprejfa. This 

 would have been altogether unneceffary, if he had not wanted to 

 make our Solar Syftem go on of itfelf after it was once fet agoing. 

 But, as I know many of the Newtonians are unwilling to believe 

 that Sir Ifaac's Syftem is fo Mechanical as I have rep»refented it, I will 

 give my rcafons for fo thinking. 



And, to begin with the Vis Imprejfa producing the projedile Mo- 

 tion of the Planets, which, according to the firft axiom, is to laft for- 

 ever 



• Ste :*hat 1 have further faid upon this fubjc£l, Vol. I. p, 525. 



