34 ESSAYS ann OBSERVATIONS 
his various inftances, importing that it holds 
in every cafe whatever. And now, taking 
the law in this fenfe, difficulties croud upon 
me; of which I (hall mention a few, that 
make the greateft figure. The firft is, thar, 
according to this law, there cannot be in 
matter, fuch a thingas refiftance without re- 
action ; a bold affertion, which contradi@s 
what appears to be the fact in common ap- 
prehenfion ; and which therefore ought not 
to be admitted, without a very compleat in- 
dution of particular cafes; more compleat, 
fo far as I can learn, then hitherto has been 
attempted. But, not to reft upon the nega- 
tive, it appears clear, that, in the collifion of 
hard bodies, there is refiftance without re- 
action: and J flatter myfelf with having made 
out above, that, were there reaction in this 
cafe, the effects of collifion would be very 
different from what they are in fact. And 
this leads to another difficulty, that if rea- 
tion were, in every cafe, equal to action, vz. 
in hard bodies as well as in elaftic; the effects 
of collifion behoved to be the fame in both. 
Two elaftic balls meeting in oppofite directi- 
ons, rebound; becaufe, after their force is 
{pent by collifion, the fame force is reftored 
to 
