INTRODUCTION. 
? 
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 
his 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 . 1 Now we find 
1 Of course it may be said that we have no evidence of jjrimjrting 
