1 14 ESSAYS AND OBSER VATia\S 



For who ever Aippofed, that ekher the ge- 

 neral or particular properties of matter 

 €Ould be difeovered in any other way ? 

 How could it fee known, whether body 

 was penetrable or iinpenetrable, divifible 

 or indivifible, eFaftic or non elaftic, ani- 

 mated or inanimated', but by trial? Sup. 

 poling, however, that we were informed 

 before hand, tlmr the body at reft waa 

 impenetrable, utterly inadlive and foft, 

 and had neither impediment nor tenden- 

 cy to motion ; what would hinder us from 

 foretelling exatflly every circumftance that 

 happens, when another body of the fame 

 kind ftrikes upon it * ? 



When a body in motion ftrikes u^poa 

 another at reft, the one lofes as much mo- 

 tion as the other gains, in the fame direc- 

 tion. This is ordinarily faid to proceed 

 from a rea(flion of the body that acquires 

 the motion. The effect is indeed the- 

 fame upon the percutient body ; there is 

 the fame change of its ftateasifit had 

 aif^ually received an impulfe in the con- 

 trary 



* Pb.il of. Efliys. 



