34* ANTIENT METAPHYSICS. Book V. 



cfTence, that a Body, being at Reft, continues at Reft. And, by the 

 fame nature and eflence, I am convinced that Sir Ifaac imderftood 

 Body to continue a Motion once given it by the Vis Tmprejfa : And 

 therefore I hold that the prefent Newtonians differ from their ma- 

 tter, when they lay afide the Fis Inftta^ and maintain that the Body 

 continues the Motion by virtue of the Impulfe^ or the Vis Imprejfa^ only. 



Underftanding, therefore, the axiom in the fenfe in which it is 

 now generally underftood, I proceed to inquire whether it be a ge- 

 neral propofition, extending to all kind of Motion, however begun, 

 whether by Body or by Mind. That Sir Ifaac applies it only to Mo- 

 tion produced by Bodily Impulfe, I think is evident, for the reafons al- 

 ready given ; and fo far, I think, he is in the right, that it only can be 

 applied to motion of that kind ; For we have no experience or obferva- 

 tionthat can carry it to Motion begun by Mind ; but, on the contrary, 

 our daily experience convinces us that the Motion begun by Mind 

 continues no longer than the Mind continues to operate, except in cer- 

 tain cafes, where the a£tion of one Mind prevails over the action of 

 another, as in the cafe of an Animal Body falling or running down 

 a fteep defcent ; in which cafe, the elemental Mind, that carries the 

 Body downward, is too ftrong foi the volition of the Animal that 

 would flop it. 



And this difference, betwixt the Motion by Mirid and the Motion 

 by Bodily Impulfe, is, I think, clearly deducible from the different 

 natures of Body and Mind : For Body can only aft upon Body by 

 its furface ; whereas Mind, having no furface, canrtot poffibly 

 a6t upon Body in that way, but operates in a manner quite different, 

 as I have explained above, that is, by Animation, which operates, 

 not by Impulfe, producing a Motion that continues fome time after 

 the impulfe ceafes, but by inceffant energies, repeated in every in- 

 ftant of the Motion, which being difcominued, the Motion ceafes. 



It 



