PHYSICAL AND LITERARY. 89 



The only immediate caufe of the motion, 

 being the adive force of the animal which 

 prelTes the medium one way, and its own - 

 body the other way, as might be parti- 

 cularly fhown in every kind of progref- 

 fion, if it were thought needful. 



Thus, iipon the moft attentive exami- 

 nation into the ftate atnd condition of bo- 

 dy at reft, we^ave found it to be per- 

 fedly inert or inactive. Body in motion 

 next demands our confideration. Suppo- 

 fing a body once put in motion by fome 

 agent or other, i\ behoves us to follow it 

 out, and inquire what happens to it on 

 this change of its ftate. An extended, im- 

 penetrable, inadiive fubftance has recei-» 

 ved a motion : Will it inftantly ftop when 

 the immediate influence of the adive 

 power ceafes I or will it perfevere in its 

 new ftate ? 



From what commonly happens in the 

 motions of bodies, their gradual lofs of 

 force and returning to a ftate of reft, peo- 

 ple contradl an early prepolTeftlon, and 

 are ready to imagine, that reft is the 

 proper ftate of body. B^t a diligent re- 



V0L.I. M tiew 



