FRICTION. 249 



dition, between the constantly fixed and the 

 constantly moveable. Such objects can and do 

 move ; but they move but for a short time if left 

 to the laws of nature. When at rest, they can 

 easily be put in motion, but still not with un- 

 limited ease ; a certain finite effort, different in 

 different cases, is requisite for this purpose. 

 Now this intermediate condition, this capacity of 

 receiving readily and alternately the states of 

 rest and motion, is absolutely requisite for the 

 nature of man, for the exertion of will, of con- 

 trivance, of foresight, as well as for the comfort of 

 life and the conditions of our material existence. 

 If all objects were fixed and immoveable, as if 

 frozen into one mass ; or if they were susceptible 

 of such motions only as are found in the parts of 

 vegetables, we attempt in vain to conceive what 

 would come of the business of the world. But, 

 besides the state of a particle which cannot be 

 moved, and of a particle which cannot be stopt, 

 we have the state of a particle moveable but not 

 moved ; or moved, but moved only while we 

 choose : and this state is that about which the 

 powers, the thoughts, and the wants of man are 

 mainly conversant. 



Thus the forces by which solidity and by 

 which organic action are produced, the laws of 

 permanence and of developement, do not bring 

 about all that happens. Besides these, there is 

 a mechanical condition, that of a body exposed 

 to friction, which is neither one of absolute per- 



