2 The Animal Mind 



the danger of confusing individual peculiarities with general 

 mental laws. In a psychological experiment, an unbiassed! 

 observer is asked to study his own experience under certain 

 definite conditions, and to put it into words so that the ex- 

 perimenter may know what the contents of another mind are 

 like in the circumstances. Thus language is the essential 

 apparatus in experimental psychology; language with all 

 its defects, its ambiguity, its substitution of crystallized con- 

 cepts for the protean flux of actually lived experience, its 

 lack of terms to express those parts of experience which are 

 of small practical importance in everyday life, but which 

 may be of the highest importance to mental science. Out- 

 side of the psychological laboratory language is not always 

 the best guide to the contents of other minds, because it is 

 not always the expression of a genuine wish to communicate 

 thought. "Actions speak louder than words," the proverb 

 says ; but when words are backed by good faith they furnish 

 by far the safest indication of the thought of others. 

 Whether, however, our inferences are made on the basis of 

 words or of actions, they are all necessarily made on the 

 hypothesis that human minds are built on the same pattern, 

 that what a given word or action would mean for my 

 mind, this it means also for my neighbor's mind. 



If this hypothesis be uncertain when applied to our fellow 

 human beings, it fails us utterly when we turn to the lower 

 animals. If my neighbor's mind is a mystery to me, how 

 great is the mystery which looks out of the eyes of a dog, and 

 how insoluble the problem presented by the mind of an 

 invertebrate animal, an ant or a spider ! We know that such 

 minds must differ from ours not only in certain individual 

 peculiarities, but in ways at whose nature we can only guess. 

 The nervous systems of many animals vary widely from our 

 own. We have, perhaps, too little knowledge about the 



