CAUSE OF ITS FAILURE. 77 



having sensation ; for sensation has to do with par- 

 ticulars." 



In another place 13 , after stating that principles 

 must be prior to, and better known than conclu- 

 sions, he distinguishes such principles into absolutely 

 prior, and prior relative to us ; " The prior princi- 

 ples, relative to us, are those which are nearer to 

 the sensation; but the principles absolutely prior 

 are those which are more remote from the sensa- 

 tion. The most general principles are the more 

 remote, the more particular are nearer. The ge- 

 neral principles which are necessary to knowledge 

 are axioms" 



We may add to these passages, that in which he 

 gives an account of the way in which Leucippus was 

 led to the doctrine of atoms. After describing the 

 opinions of some earlier philosophers, he says 14 , 

 "Thus, proceeding in violation of sensation, and 

 disregarding it, because, as they held, they must 

 follow reason, some came to the conclusion that the 

 universe was one, and infinite, and at rest. As it 

 appeared, however, that though this ought to be by 

 reasoning, it would go near to madness to hold such 

 opinions in practice, (for no one was ever so mad as 

 to think fire and ice to be one,) Leucippus, therefore, 

 pursued a line of reasoning which was in accordance 

 with sensation, and which was not irreconcileable 

 with the production and decay, the motion and mul- 

 titude of things." It is obvious that the school to 



13 Anal. Post. i. 2. i 4 De Gen. et Cor. i. 8. 



