THE NEWTONIAN PHILOSOPHY. 547 



unlverfe is fuftained and preferved, and the bufinefs of nature carried 

 on, is, I think, evident, from the vacillancy and inconfiftency of his 

 opinions upon this fubjedt. 



In his Principia, he fays nothing at all of the caufe of the attradlion 

 or gravitation of the celeftial bodies ; only, he tells us, negatively, 

 that he does not affirm gravitation to be eflential to matter. But, as 

 to the attradion of the fmall particles of matter at very fmall diftan- 

 ces, and the cohefion of bodies, he affirms, in the Scholium fubjoined 

 to his Principia, that they, as well as eledricity, fenfation, and the 

 voluntary motion ot animals, are produced by a moft fubtile fpirit, 

 which pervades grofler bodies, and is latent in them *". But, in his 

 fecond thoughts upon the fubjed, I mean his Queries, fubjoined to 

 the laft edition of his Optics, he affigns for the caufe of all the mo- 

 tion in the unlverfe, certain adive principles, by which the particles 

 of matter are moved, and which, he fays, are the caufes of gravitation, 

 oi magnetic and ^/^^nV attractions, of fermentation, and the cohefion of 

 bodies f. And, in another paflage in the fame Query J, he fays ex- 

 prefsly, that the 'uis inertiae, by which bodies perfift in their motion 

 or reft, and which he infifts fo much upon in his Principia, making 

 it, together with attradion, the principle of the motion of the celeftial 

 bodies, is not fufficient, either to put bodies in motion, or to keep 

 them in motion ; and that, therefore, fome other principle is ne- 

 ceflary for that purpofe ; which principle can be no other than that 

 adive principle in matter which he afterwards mentions §. Now, as 



Z z z 2 here 



* See the pafTage quoted at large, in Sir Ifaac's own words, page 275. 



t Pages 376. 377. of his Optics, Eiiglilh edition, 1721. % Pages 372. 373. 



5 His words are, * The vis inertiae is a paflive principle, by which bodies perfifl 



* in their motion or rtfl:, receive motion in proportion to the force impreding it, and 



* refifl: as much as they are refifled By this principle alone there never could have 



* been any motion in the world ; fomeother principle was neceflary for putting bodies 

 into motion, and now they are in morion, fome other principle is neceflary for confer- 



* ving motion •,' Pag. 372. 373. Here he appears to give up theflrange notion of bodies 

 continuing to move by their vis inertiae^ and afcribes their continuance of motion to 



thofe 



