“PHYSICAL Ay» LITERARY. 7 
«mentary particles of the one, may have a 
“ greater inertia than equal folid elementary 
§ ee particles of the other kind.”” This conje- 
 @ure, if true, would effectually overturn 
what hath been now advanced. But it ap- 
pears to be equally inconfiftent with his own 
account of inertia, and occurs only in a poft- 
humous work. ‘(he iertia of body isa 
negative quality, or a negation of all pofitive 
power, and therefore can admit of no de- 
grees of greater or lefs in a given quantity of 
matter. ‘Two bodies, or two elementary 
particles of equal quantities of matter, if 
they are inert at all, muft have equal svertia, 
or require equal forces to move them with 
equal velocities. And, in every cafe, the 
inertia is proportional to the quantity of mat- 
ter. 
_ Ir a body left at reft does not begin mati- 
. on of itfelf, it is determined to remain in 
q that ftate; not from any real repugnance to 
' motion, which is as conformable to its na- 
b ture as a fate of reft: but becaufe nothing 
is done without a caufe. And, when acted 
7 m by any external influence, it obeys 
without reluctance; the motion produced 
being in) exact proportion to the moving 
Pin caufe. 
