Chap. V. ANTIENT METAPHYSICS. 387 



manner altogether different, there is an end of that argument. 2do, If 

 it were true, what the Jcfuit commentators upon Sir Ifaac fay *, that 

 all Motion is by nature ledilineal, it would follow of neceiliiry con- 

 fcquence, that the Motion of the Planets, and, indeed, every Motion 

 in a Curve, muft be necefTarily compounded. And no doubt the 

 propofition is true, if the Curvilincal Motion be produced by Body : 

 But, on the other hand, if the Motion be produced by Mind, I fay 

 there is no fuch necefhty. 



As I have fliown that it is only from the confcioufnefs of our own 

 Motions that we have any idea of Motion by Mindf, I think, in phi- 

 lofophifing on that kind of Motion, we ought to begin at home, as 

 Des Carres began his philofophy, when he fct out with that famous 

 propofition, ' I think ; therefore I am J.' Now, as Des Cartes knew, 

 by Confcioufnefs, that he thought, fo 1 know, by the fame Confciouf- 

 nefs, that my Mind moves my Body ; and that, therefore, it is not 

 moved by any external Caufe, but by an internal principle of Move- 

 ment. 



I fay further, that I know, upon the fame ground of certainty, 

 that my Mind can not only move my Body in a ftraight line, but in 

 a curve of any kind. And though I may not be able, in walking to 

 defcribe a curve, fuch as a circle or an elllpfis, fo perfectly, by rea- 

 fon of the divifion of my Motion by my limbs, I find that, when 

 there is no neceffity for the Motion being divided in that way, as 

 when I defcribe a circle upon the table or in the air with my hand, 



C c c 2 the 



* See p. 332. t See page 87. 88. 89. 



X This propofition has, I know, been treated by fome as a ridiculous tautology. 

 But, I think, it is a juft conclufion of reafoning, proceeding upon the fureft ground 

 of certainty, I mean Confc'mtjntfs ; and the argument plainly is this : I know by 

 Confcioufnefs 'that I think; and from thence I infer that I exift;* becaufe every 

 thing that ads muft exift : Nor, indeed, du we otherwife know that any thing cs- 

 ifts. 



