PSYCHOLOGY 259 



which cannot be imagined without a definite material founda- 

 tion. " The correct interpretation of psychic activity cannot be 

 arrived at by introspection alone, although this is the necessary 

 method of inquiry for the study of consciousness ; exact physio- 

 logical analysis based upon observation and experiment must 

 also be employed, and from this the laws of the ' mind-life * 

 may follow." 



These contradictory views as to the nature of the mind lead 

 to a further question : What is the relation of the human to- 

 the brute mind ? The philosophers of olden times generally 

 admitted no qualitative distinction, only a quantitative one, 

 Christianity, on the contrary, laid down a fundamental differ- 

 ence between man's immortal mind and the mortal mind of the 

 animal, and maintained it rigidly as an unassailable dogma, the 

 more effectively since there was no lack of philosophers who 

 brought all the weight of their dialectic to prove that dualism 

 was self-evident. This dualism reached its zenith at the hands 

 of Descartes, who taught that man alone had a mind, feeling 

 and free-will, while the whole of brute creation were mere 

 automatic machines. Even in later days and in our own times 

 psychology as an integral section of physiology is limited to the 

 human mind. 



It is true that a start was made in the direction of compara- 

 tive psychology early in the last century, but books such as 

 Scheitlin's Investigation of the Animal Mind (Tierseelenkunde) 

 possess a value only as interested attempts to discover a mind 

 in animals ; no really scientific animal psychology was the 

 outcome of such works, for they were entirely devoid of an 

 exact scientific basis. The first to attempt the solution of 

 these problems was that master of comparative anatomy and 

 physiology, Johannes Miiller. He showed the way to an. 

 accurate, unbiassed estimate of the animal mind, and so to 

 comparative psychology, although at the outset this compari- 

 son did not clearly demonstrate the general resemblance and 

 the variation in details. It was left to Darwin to find the true 

 balance of the harmony and discord, and to show that the 

 difference between man and beast is one of degree not of kind. 



In his book, The Descent of Man, which first appeared in 

 1871, Darwin drew attention to the important human resem- 



17* 



