82 ESSAYS AND OBSERVATIONS 



To give the quefliori a fair examina- 

 tion, we fliall, iuftead of fpeaking about 

 matter or body, fuppofe for once, a fub- 

 flance before us quite inadive of itfelf, 

 which is extended, impenetrable, finite, 

 land confequently moveable. Let us try 

 if any lefs refiflance to motion can be ex- 

 pecfled here, than is adlually to be met 

 with from common matter. Place any 

 mafs of fuch a fubflance at reft. It can- 

 not begin motion of itfelf by the fup- 

 pofition. But an adive animated being, 

 as for example, a man, can move it. Some 

 effort muft certainly be made, fome pow- 

 er exerted, to produce this effed. It will 

 never be pretended, that the fame effort 

 can move the mafs either with a great ve- 

 locity or a fmall velocity ; that being as 

 abfurd, as to fay that a great velocity and 

 a fmall velocity are one and the fame 

 thing. In like manner, it mufl require 

 one effort to move a fmall quantity of the 

 fubftaace with a certain velocity, and a 

 different effort to move a great quantity 

 with the fame velocity. The fame cTiergy 

 of the agent will never ferve to move a 



given 



