PHYSICAL ANp LITERARY. 21. 



fy to feparate motion from body, by fup-, 

 pofing it to be at reft. But what we have 

 principally to confider in the prefent ar- 

 gument is, that the moulding 9f a body, 

 into a certain figure, or the giving it a 

 certain colour, are not imperfedl, but com- 

 pleated effedts ; which, once produced^ 

 muft continue invariably the fame, until 

 fome power be exerted to make an altera- 

 tion. This is involved in the very con- 

 ception of colour and figure, and is fp 

 fimple and clear a propofition, as to be in- 

 capable of any illuftration. The bare ne- 

 gation of a new caufe, is fufiiclent to ac-r 

 count for the continuance of fuch efFe«5ls. 

 Reft is of the fame kind. It requires no 

 a(5lion nor operation to prefer ve a body 

 at reft, more than to preferve its colour 

 or figure. But motion, being the diredl 

 oppoiite of reft, cannot be one of thofe 

 compleat efFeds, which, once produced, 

 fnuft continue invariably the fame. 

 Motion, by the very conception of it, 

 is aclion. While a body is in motion, 

 it is in continual a(5lion; and, as ac- 

 t;ion implies power, there muft be a 



power 



