160 EVOLUTION AND MAN S PLACE IN NATURE 



on what this possession depends, science has no 

 testimony to offer. 



Thus it appears that for study of_ the phenomena 

 of intelligence, we must pass away Jroni research 

 into organic structure and function. We must pass 

 into consciousness. Here alone, direct knowledge is 

 to be obtained of mental phenomena. The distinction 

 between the two modes of inquiry is clear, and all 

 that has been already said as to guarding against the 

 intrusion of the one into the sphere of the other, is 

 confirmed. \Ve are studying human experience in 

 order to reach definite conclusions as to animal 

 experience. For success, we require a more rigid 

 separation of sensory experience from intelligent 

 discrimination, as both appear in human life. So 

 predominant is intellectual activity in human history, 

 that it is not habitual with us to distinguish rigidly 

 between physical and mental contributions to our 

 experience. But the distinction needs to be rigidly 

 drawn here. The broad lines of separation are mani 

 fest in action, such as between food and knowledge, 

 between muscular exercise and reflective, between 

 observation of the external world, and the succession 

 of fancy and feeling in our consciousness. We do 

 not commonly attempt to trace for ourselves how 

 much is to be attributed to organism, how much to- 

 intelligence, when we admire a flower, or express an 

 opinion, or resolve to check an evil habit. As long- 

 as the one side is prominent, whether it be physical 

 or mental, we readily distinguish the one from the 

 other. But when contributions from both sides 

 intermingle, we do not easily discriminate, and not 

 infrequently our entire experience is attributed to 



