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impulses and volition ; but from such 

 motions it seems impossible to account for 

 sensation or volition. We can conceive 

 no variety in these motions, but what re- 

 lates to degree, duration, and succession, 

 and it seems impossible to believe that 

 sensation can be the result of such mo- 

 tions, or that ideas can arise from any 

 succession or train of them. Certain per- 

 sons will therefore I doubt not continue 

 to think that sensation, remembrance, 

 comparison, judgment, and volition, are 

 properties of some distinct substance. 



The essences or primitive parts of what 

 we call matter, are too subtile to be per- 

 ceived by our senses, and seem even to 

 elude our conceptions. Is it not then 

 most philosophical to acknowledge our 

 ignorance on these points, and to speak 

 of what we do know, the properties of 

 the different species of substances in na- 



