INTRODUCTION. 7 



inadequate in the other. And likewise, of course, with all 

 other exhibitions of mental life. 



It is quite true, however, that since the days of Des- 

 cartes — or rather, we might say, since the days of Joule — 

 the question of animal automatism has assumed a new or 

 more defined aspect, seeing that it now runs straight into the 

 most profound and insoluble problem that has ever been 

 presented to human thought — viz. the relation of body to 

 mind in view of the doctrine of the conservation of energy. 

 I shall subsequently have occasion to consider this problem 

 with the close attention that it demands ; but in the 

 present volume, which has to deal only with the pheno- 

 mena of mind as such, I expressly pass the problem aside 

 as one reserved for separate treatment. Here I desire 

 only to make it plain that the mind of animals must be 

 placed in the same category, with reference to this pro- 

 blem, as the mind of man ; and that we cannot without 

 gross inconsistency ignore or question the evidence of 

 mind in the former, while we accept precisely the same 

 kind of evidence as sufficient proof of mind in the latter. 



And this proof, as I have endeavoured to show, is in all 

 cases and in its last analysis the fact of a living organism 

 showing itself able to learn by its own individual experi- 

 ence. Wherever we find an animal able to do this, we 

 have the same right to predicate mind as existing in such 

 an animal that we have to predicate it as existing in any 

 human being other than ourselves. For instance, a dog 

 has always been accustomed to eat a piece of meat when 

 liis organism requires nourishment, and when his olfactory 

 nerves respond to the particular stimulus occasioned by 

 the proximity of the food. So far, it may be said, there 

 is no evidence of mind ; the whole series of events com- 

 prised in the stimulations and muscular movements may 

 be due to reflex action alone. But now suppose that by a 

 number of lessons the dog has been taught not to eat the 

 meat when he is hungry until he receives a certain verbal 

 signal : then we have exactly the same kind of evidence 

 that the dog's actions are prompted by mind as we have 

 that the actions of a man are so prompted.^ Now we find 

 ^ Of course it may be said that we have no evidence of prompting 



