^^P'l- APPENDIX 3or 



pofition in any way, is, by the nature of things, impoffible. And I 

 will bring the Matter to a very fhort ifTue ; for I fay that the Newto- 

 nians, in order to prove that the Motion is in any way compound- 

 ed, muft maintain one or other of the three following propofitions : 

 Either that it is impoffible, by the nature of things, that there can 

 be a circular or elliptical Motion without the compofition they fup- 

 pofe J or, 2do, That, if it could be produced without fuch compo* 

 fition, the Planetary Motion fo produced would not be governed by 

 thofe laws which we know govern it, nor have thofe properties 

 which we know it has ; or, laftly. That there does adually exift in 

 our folar fyftem, diffufed through the whole of it, a ^is centripeta 

 by which all the feveral planets tend towards the fun, in the fame 

 manner as Bodies here on earth tend to the centre of it. 



As to the firft of thefe propofitions, I need not repeat what has 

 been already faid, and what, I think, muft be admitted by every 

 theift, that, if the univerfe be the produdion of infinite Power and 

 Wifdom, every Motion in it muft be as fimple as pofTible *, and if it 

 can be produced by one caufe, more than one will not be employed. 

 This is a maxim in which both Ariftotlc and Sir Ifaac Newton a- 

 gree f ; and it is dcmonftrated, not indeed from geometrical or me- 

 chanical principles, but from principles much higher, I mean meta- 

 phyfical and theological. Now, if it be true that the fimple Motion 

 is impoffible, it is certainly a propofition which may be dcmonftra- 

 ted by geometry ; for it concerns the generation of a geometrical fi- 

 gure, fome of which, fuch as a cone or a cylinder, we know, Eu- 

 clid has defined by the way in which they are generated. And 

 with refpe«5l to a circle, he has told us that it is a plain figure, com- 

 prehended under one line ; and it is a poftulatum of his, that a circle 

 may be defcribed round any centre, and at any diftancc. And it has 



always 



* See the definition that I have given of Ample and compounded Motion, Vol. ii. 



p. 389- 



f See Note Fivll of page 292. 



