160 HABIT AND JNTELLIGENCE. [cHAP. 



become conscious of a self which has the feelings, and yet 

 is not merely the sum-total thereof ; ^ and in inferring the 

 existence of an external world we infer, as I think, the 

 existence not only of "permanent possibilities of sensa- 

 tion," but of objects to which we refer the sensations. 

 Axioms I regard the following as axiomatic truths : — 1. That 



physics' where there are properties there must be substance ; 



2. where there is relation, there must be things related ; 



3. where there is action, there must be an agent ; and I am 

 inclined to add, as a truth belonging to the same category, 



4. that where there is an effect there must be a cause. 

 The question whether we have any idea of substance as 

 distinct from mere permanence is a parallel one to the 

 question whether we have any idea of causation as dis- 

 tinct from mere succession. In the last chapter I have 

 stated my belief that our idea of causation is not resolvable 

 into mere succession. I regard the four metaphysical 

 axioms stated above, like the logical axiom that a contra- 

 diction cannot be true, as necessary truths of intelligence ; 



Beliefs not and tte belief in them is a result neither of mental habit, 

 of \ho™ht ^^^ °^ inference from data of experience ; on the contrary, 

 but ini- it is implied in all thought and all experience, and without 

 thmight it neither thought nor experience would be possible.^ 



Belief Further : we have a belief in the veracity of memory ; 



^"radtv that is to say, we believe that as perception gives us^ true 



of memory information of present reality, so memory gives us true 



information of past reality. It is to be observed that the 



belief in a past reality as corresponding to an impression 



of memory is not implied in the mere presence of the 



mind to call it a permanent liability to feeling. I think this inconsistent : 

 but it is not the result of any oversight ou Mr. Mill's part. 



> " Cogito, ergo sum," said Descartes : not meaning by this celebrated 

 saying to prove his own existence, which neither needs proof nor admits 

 of it ; but to state the truth that it is in the act of thinking we become 

 conscious of our own existence. 



2 It is scarcely necessary to remark, that the belief, or knowledge, of 

 these truths is not necessarily conscious knowledge, and does not imply 

 the power of stating them in words. Men were not conscious of knowing 

 them till they had begun to think about thinking. 



