164 EVOLUTION AND MAN S PLACE IN NATURE 



intelligence includes, and wherein it differs from 

 human intelligence. 



In entering upon this department of comparative 

 psychology, the question whether psychology is a 

 natural science must be laid aside as of no importance. 

 The question concerns nothing more than the matter 

 of naming, and we shall have to determine verbal 

 usage according to the conclusions reached. In 

 dealing with structure, functions, and their scientific 

 interpretation, the suitableness of our employment of 

 terms must be settled by the results of investigation. 

 If any one say that natural science closes with 

 application of the microscope, it is certain that 

 external observations are closed at this limit. On 

 the other hand, if man belongs to Nature, and 

 consciousness belongs to man, the study of our own 

 consciousness lies within the sphere _of natural 

 science. When from this we turn to judge of 

 mental phenomena in the life of a dog, we are clearly 

 in the region of natural science. Either this must 

 be admitted, or the claim to include man within 

 Nature must be given up. There is no alternative. 

 That the inclusion of the whole life of man, bodily 

 and mental, within Nature, is the only tenable 

 position, is beyond dispute. The distinction between 

 external observation and consciousness, as two distinct 

 modes of knowing natural phenomena, is, however, 

 rigidly drawn. It is acknowledged that there is no 

 available mode of bridging the chasm which separates 

 them. In our own life, they are distinct ; and their 

 relation to each other can be judged from the facts 

 of our life alone. The contrast between physiology 

 and psychology is final, and must regulate biological 



