Ill THE ORIGIN OF THE IMPRESSIONS 91 



manner, you still find motion or a change of relation. 'Tis 

 absurd to imagine that motion in a circle, for instance, should 

 be nothing but merely motion in a circle ; while motion in 

 another direction, as in an ellipse, should also be a passion 

 or moral reflection ; that the shocking of two globular parti- 

 cles should become a sensation of pain, and that the meeting 

 of the triangular ones should afford a pleasure. Now as these 

 different shocks and variations and mixtures are the only 

 changes of which matter is susceptible, and as these never 

 afford us any idea of thought or perception, 'tis concluded to 

 be impossible, that thought can ever be caused by matter. 



"Few have been able to withstand the seeming evidence of 

 this argument ; and yet nothing in the world is more easy 

 than to refute it. "We need only reflect upon what has been 

 proved at large, that we are never sensible of any connection 

 between causes and effects, and that 'tis only by our expe- 

 rience of their constant conjunction we can arrive at any 

 knowledge of this relation. Now, as all objects which are 

 not contrary are susceptible of a constant conjunction, and as 

 no real objects are contrary, I have inferred from these 

 principles (Part III. 15) that, to consider the matter a priori, 

 anything may produce anything, and that we shall never dis- 

 cover a reason why any object may or may not be the cause of 

 any other, however great, or however little, the resemblance 

 may be betwixt them. This evidently destroys the precedent 

 reasoning, concerning the cause of thought or perception. 

 For though there appear no manner of connection betwixt 

 motion and thought, the case is the same with all other causes 

 and effects. Place one body of a pound weight on one end 

 of a lever, and another body of the same weight on the other 

 end ; you will never find in these bodies any principle of 

 motion dependent on their distance from the centre, more than 

 of thought and perception. If you pretend, therefore, to 

 prove, a priori, that such a position of bodies can never cause 

 thought, because, turn it which way you will, it is nothing but 

 a position of bodies : you must, by the same course of reason- 

 ing, conclude that it can never produce motion, since there is 

 no more apparent connection in the one than in the other. 



