ANIMAL AND RATIONAL INTELLIGENCE 175 



to sound as a stimulant of action. In proof of exer 

 cise of intelligence, examples are many and familiar, 

 making it unnecessary to enter upon detailed refer 

 ences. 1 As to human intelligence, evidence connected 

 with physical aptitude, beginning with human speech 

 as the expression of thought, passes upwards through 

 all the acquisitions and achievements connected with 

 skilful manipulation, and with development of musical 

 gift and artistic faculty. Within this department of 

 inquiry evidence is supplied sustaining the conclusion, 

 that the higher mammals possess a form of intelligence 

 sufficient for interpreting other symbols, besides the 

 expressions of sensibility belonging to the natural 

 life of their species. The dog is conspicuous here, 

 standing in marked advance of the other members 

 of the group, monkeys, apes, and horses. This 

 superiority is the result of companionship with man. 

 Possibilities of training thus become a valuable test 

 of comparative intelligence. 



From this we pass to an additional group of pheno 

 mena connected with the social life characteristic 

 of the several species. This transition somewhat 

 alters the view of the classifications of animals. In so 

 far as gregarious tendencies involve a more uniform 

 and extended manifestation of social feeling, sheep 

 and oxen take precedence of the higher mammals. 

 Within the higher group, monkeys take precedence 

 of the apes ; while horses and dogs supply less valu 

 able evidence of social feeling. Domestication has con 

 siderably obscured the range of natural feeling in the 

 life of both the horse and the dog. These diversities 



1 Of details, I have made account in The Rdalion of Mind and 

 Jirain, chap, vii, 



