3/6 ANT IK NT METAPHYSICS. Book V. 



But Sir Ifaac Iuig elfewhere declared his Mind ftill more e\{)licitly 

 upon this fubjecl:, and, indeed, as ftrongly as it is poffiblc for words 

 to exprefs it ; for, in a letter to Dr Bentley, dated 25th February 

 1692-3, he has ufed thefe words : ' It is inconceivcable that inani- 

 ' mate Brute Matter fhould, without the mediation of fomething 

 *■ clfe, operate upon and affedt other Matter, without contact, as it 

 ' muft do, if Gravitation, in the fenfe of Epicurus, be eflential and 

 ' inherent in it : And this is one reafon why I defired you would 

 ' not afcribe Innate Gravity to me. That Gravity fliould be innate, 

 ' fo that one Body may act upon another at a diftance, through a 

 ' Vacuum, without the mediation of any thing elfe, is to me fo great 

 ' an abfurdity, that I believe no man, who has a competent faculty 

 ' of thinking, can ever fall into it. Gravity muft be caufed by an 

 ' agent ading conftantly according to certain laws. But whether 

 ' this agent be Material or Immateria.1, I have left to the confidera- 

 ' tlon of my readers *.' 



For the fame reafon that thefe philofophers maintain that Body 

 can attract Body at a diftance, they muft maintain that it can like- 

 wife repel Body at a diftance, fmce the one is as common a phaeno- 

 menon, at leaft here on Earth, as the other ; and as all the changes 

 of corporeal things, and all the various feparations and new aflbcia- 

 ations, (to ufe the words of Sir Ifaac, above quoted f), are performed 

 by the particles of Matter either attracting or repelling one another, 



the 



* The laft words of this paffage I would defire the reader to obferve, as they feem 

 to roe to indicate the progrefs of Sir Ifaac's opinion concerning the caufe of the Mo- 

 tion of the Celeftial Bodies. When he wrote his Principia, he feems to have thought 

 that their Motion was produced by the Impulfe of other Bodies : When he 

 wrote this Letter to Dr Bentley, he appears to have formed no opinion whe- 

 ther the Motive Power was Body or Mind : But, when he wrote the Queries 

 annexed 10 the fecond edition of his Optics, which was fcveral years after the Letter 

 to Dr Bentley, he determined the matter clearly in favour of Mind. 



t Page 358. in the Note. 



