PHYSICAL ann LITERARY. 19 
ter. Every body muft be of a certain fize », 
and figure; but it is eafy to feparate motion 
from body, by fuppofing it to be at reft. 
But what we have principally to confider in 
the prefent argument.is, that the moulding 
of a body into a certain figure, or the giving 
it acertain colour, are not imperfect, but 
compleated effects ; which, once produced, 
muft continue invariably the fame, until fome 
power be exerted to make an alteration. This 
is involved in the very conception of colour 
and figure, and is fo fimple and clear a pro- 
pofition, as to be incapable of any illuftrati- - 
on. The bare negation of a new caufe, is 
{ufficient to account for the continuance of 
fach effects. Reft is of the fame kind. It 
- requires no action or operation to preferve a 
4 - body at reft, more than to preferve its colour 
or figure. But motion, being the direct op- 
pofite of reft, cannot be one of thofe com- 
pleat effects, which, once produced, mutt 
continue invariably the fame. Motion, by 
_. the very conception of it, is action. While 
3 a body is in motion, it is in continual action ; 
and, as action implies power, there muft be 
S, a power continually exerted to preferve a bo- 
" dyin motion. Again, if motion be confi- 
* ; dered 
