ro2 ESSAYS ann OBSERVATIONS 
fhortnefs, we may, and always do call, che fed 
of reaction; but we can never imagine that 
there is any real active oppofition of the bo- 
dy at reft to the motion of the other. The 
great difficulty complained of, is in concei- 
ving, how the one body has its motion dimi- 
nifhed by the f{troke as much as the other is 
increafed, while there is no active repugnan- 
cy allowed in the one to the other. It would 
be ridiculous enough to fancy, that the mo- 
tion ‘of the one was a part of the motion of 
the other; and that the very fame motion 
could be transferred from the one into the 
other. ‘* As well might the magnitude, fi- 
“¢gure, or colour, of one body be imparted 
“to another.” But this we may venture to 
fay, that, for ought appears to the contrary, 
it follows from the nature of a paflive, ex- 
tended and impenetrable fubftance, that mo- 
tion is loft in one by producing it in another. 
It will be eafily admitted, that one motion — 
may deftroy an oppofite motion, and by that 
means lofe of its own. Yet there is no lefs 
difficulty here, than in the communication of 
motion. If two pieces of clay oppofing 
each other with equal forces, had any real a- 
tivity of their own, it might be expected, 
that 
