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absolute pa&siveuess in matter, and the effect of no po- 

 siiive nisus, an unmechanical matter can exert no resist- 

 ance to change the state : and of consequence an atom 

 would have as much power to move a planet, as a planet 

 to move an atom. 



An action or tendency to action is plainly implied in 

 a nisus to any state. And as a nisus to passiveness is a, 

 contradiction in terms, it follows, that the properties of 

 power and motion, cannot be considered in matter taken 

 abstactediy, but qs composed into a system. Therefore, 

 though it must be allowed, that the changes of state in 

 matter are proportioned to the powers that produce 

 them, yet it is impossible to conceive, that the power 

 shall continue in the body acted upon, after the exterior 

 power ceases to act upon it. 



12. The third supposed law of motion is this : when 

 matter is put into motion, it communicates as much re- 

 sistance towards stopping the motion of the body that 

 moves it, as it receives motion from it. 



Philosophers never had it in their power to make the 

 experiments on which this law is grounded, upon any 

 bodies but such as were under the influence of gravita- 

 tion. And if this axiom can be proved to depend upon 

 gravitation, it must cease to be an axiom, as being only 

 an accident depending upon another acknowledged cause. 



Resistance or re-action must be produced whereever 

 matter in motion encounters matter moving or tending 

 to move in an opposite or a different direction. Now 

 all bodies tend or gravitate toward the eariii. There- 

 fore this tendency must re-actor resist according to its 

 quantity, every power applied to move a gravitating 

 body in any other direction. 



We have no way to estimate the quantify of matter 

 contained in any bo.dies, but. the quantity of their gra- 

 vitation. Hence we must necessarily infer, that the law 

 of re-action, is not according to the quantity of matter in 

 particular detached parcels thereof, but according to the 



