so ESS.WS AND OBSERVATIONS 



of prefervingthat degree of celerity which 

 is once beflowed upon it. 7 he body, by 

 this power, is dlrecled to move in a ftreight 

 line. But we perceive nothing in the na- 

 ture of this power to confine its operation 

 to a ftreight line, more than a curve. 

 And we may fuppofe the power dill far- 

 ther varied, to make the body, inftead of 

 moving in a ftreight line, or in a curve, 

 to diretfl its equable motion tovpards any 

 other given body, within a certain di- 

 ftance. In general, as we have no means 

 to difcover power in any being but by 

 the efFeds produced ; fo the nature and 

 operation of the power are only to be dif- 

 covered by the fame means. We have no 

 fuch conception of any power as to regu- 

 late its operations by one law more than 

 by another. And this leads to the caufe 

 of gravity or attraction. We eafily con- 

 ceive the vis injita, or a power in matter 

 to continue its motion in a ftreight line : 

 It is equally eafy to conceive a power in 

 matter by which every particle has a ten- 

 dency to be united with every other par- 

 ticle. Vary the *uis uifita in the two fol- 

 lowing 



