Chap. VIII. ANTIENT METAPHYSICS. 437 



towards one another. They are the more inexciifable for fpeaking 

 in this way, that Sir Ifaac has entered his caveat againft fuch an er- 

 ror, and has exprefsly faid, that he ufes the word Attraiilion, not 

 to denote a Caufe, but an EfTedt, viz. the tendency of Bodies to- 

 wards one another, v/hatever the Caufe of that tendency may be. 



Thofe who maintain that the Earth does adually attrafl: the 

 Moon, and the Sun the Planets, at fuch an immenfe diftancc from 

 them, may, I think, for the fame rcafon, maintain that thofe 

 Centres of the Planets are the Caufe of their whole Motion ; for, 

 if they can operate where they are not, by drawing the Planets to 

 them, they may as well be the Caufe of the whole Motion, and 

 make the Planets revolve round them in Ellipfes, in the fame manner 

 as the Hand makes the Stone go round in a Sling. And this will 

 fimplify the Syftem exceedingly ; for it will account for their Mo- 

 tions, without either Gravitation or Projedtion, without Centripetal 

 or Centrifugal Forces. That this is not Sir Ifaac's fyftem is evident. 

 And yet I defy thofe who underftand Attradlion, in the fenfe of 

 Bodies drawing other Bodies towards them, to give any good reafon 

 why it might not be his fyftem. 



Some of the followers of Sir Ifaac, not contented with carr)-ing 

 Gravitation beyond the utmoft bounds of our atmofphere (withui 

 which we are warranted, by fa£t and experiment, to believe that it 

 takes place) to the Moon, and through the whole Solar Syftem, even 

 to the Orbit of Saturn, want to extend it to other fyftems, and, in 

 fhort, through the whole Univerfe, and to make one fyftem gravi- 

 tate towards another, and all the fyftems to gravitate towards fome 

 point, which they make to be the Centre of the Univerfe*. In ftiort, 



wherever 



* Therewas publifhed in London, in the yeai 1777, a pamphlet, entitled, • Thoughts 



* on General Gravitation,' written, as I am told, by an ingenious gentleman of the 



Univerfity of Glafgow. The idea of this author is grand and noble. He uiidctftands 



that the Univerfe confifls of many Syftems, fuch as our S^lar Syftem, and that they a!l 



3 move 



