Ghap. II. ANTIENT METAPHYSICS. ii 



can underftand nothing by it, except that Sir Ifaac fuppofes gravitation 

 to be produced by impulfe of body, as well as the motion of projec- 

 tion ; which further conhrms what I have laid, that he underftood 

 that caufe of motion, which is perceived by the fenfc. to be the only 

 caufe. And tliat he had no idea of mind being the caxife of motion 

 there is a further proof, befides what I liave mentioned, from his 

 making the planetary motion to be compounded of the two motions 

 of projedlioii and gravitation : For if he had known that mind coukl 

 move body, he would have known at the fame time that it could 

 move it in any diredion, ehher in a ftraight line or a curve ; and 

 fo he would have known that it was quite unneceflary to compound 

 the planetary motion, as mind, and one mind only, could move 

 them round the fun, or give them any other motion, fuch as that 

 upon their own axis. In this Xvay, the planetary motioh would 

 be pcrfedly fimple, and fuch as we muft fuppofe all the motions of 

 nature to be, when they can be performed in that way ; for there 

 is nothing more true than what Ariftotle has faid, that as nature 

 does every thing that is neceffary or proper, fo fhe does nothing 

 that is unnecefTary. It appears, therefore, that if Sir Ifaac had un- 

 derftood the nature of motion by mind, he would have made his 

 fyftem of the motion of the Heavenly Bodies much more fimple, 

 and, confequently, more perfe»5t. And in thiy way he would have 

 avoided materialifm, or the imputation of athiefm, which could not 

 have been charged againft him ; but which, I think, is unavoidable, 

 according to the account that he gives of the motion of the Celeftial 

 Bodies. For if thefe motions, fo wonderful and fo perfectly regu- 

 lar and orderly, and agreeing fo well with one another, are produ- 

 ced by material caui'es, we muft, I think, fuppofe, that the whole 

 fyftem of nature, both in heaven and earth, is produced in the fame 

 way ; fo that the whole material world is not produced or governed 

 by God, but by Body moving itfelf and moving other bodies. 



B 2 Ther<; 



