THE NEWTONIAN PHILOSOPHY. 551 



From thefe obfervations, 1 think, not only our philofophical fyflein 

 of Theifm will be much improved, but it appears to me, that the ad- 

 mirers of Sir Ifaac Newton are indebted to me for clearing his philo- 

 fophy of many doubts and difficulties to which it is liable; for it ftands, 

 at prefent, upon four hypothefes, or poflulata^ none of which can be 

 eafily granted ; but with none of which his lyftera, in my apprehcn- 

 {ion, has any thing to do. The Jirfi and, capital one, and which made 

 the other three neceflary, is, That, at fome time or another, when this 

 frame of things had a beginning, the planets were put in motion by 

 projection in a ftraight line. Secundo^ That the power of gravitation 

 prevails in the heavens as well as here on earth, by which this ftraight 

 line was bent into a curve. Tertioy That a body, put in motion in a 

 ftraight line, will continue in motion forever, if it be not ftopped by 

 fomething external. And, laftly^ That the motion of the celeftial bo- 

 dies might not be fo ftopped, the Newtonians maintain, that their mo- 

 tion is in vacuo. 1 he three firft of thefe hypothefes I have given my 

 reafons for not believing, which I hope will be fufficient to make them 

 appear at leaft doubtful, and requiringa further examination. And, as to 

 ^ vacuum, it is well known that many philofophers, both antient and 

 modc-n, have denied it ; and even Sir Ifaac himfelf has given it up, 

 when he endeavours to account for the motion of the celeftial bodies 

 by a fubtile fluid. On the other hand, 1 maintam, that Sir Ifaac's phi- 

 lofophy requires none of thefe fuppofitions, but ftands upon a firm 

 bottom of fads and obfervations, and principles of geometry, which 

 cannot be contraverted. From the fads, he has, by a wonderful in- 

 dudion, colleded general laws, concerning the motions of the celeftial 

 bodies ; and from thefe general laws he has reafoned downwards, de- 

 monftrating, a priori^ what was before only known by experience and 

 obfervation, determining fome things much more accurately than they 

 can be determined by any obfervation, and accounting for many things 

 which before were thought unfurmountaule difficulties, and unaccount- 

 able oddities in the fyftem of nature. If, therefore, he bad taken the 



motions 



