MAN. 365 



young in the discoveries of the race. The use of language 

 has been the great instrument whereby the power of ab- 

 stract reasoning has been developed, and this has produced 

 the great increase in size and complexity of the brain. 



359. Mental Life of Man, Habits, Instincts, Reason. 



Fundamentally, the mental life of man, no less than that 

 of the lower animals, is the function of the brain and its 

 accompanying systems of organs. Like that of all the 

 other animals, much of man's life and activities is made 

 up of habitual actions that have been acquired through 

 trial and experience and the crystallizing of these through 

 memory. Much of it, quite as really as in the lower 

 animals, is of those more mysterious impulses (instincts) 

 that we do not get by our own experiences, but which 

 belong to our make-up in some way as an inheritance 

 from the past of our ancestors. The mind of man, work- 

 ing upon these experiences and internal feelings and using 

 language to make clear to others his states and to convince 

 them of his conclusions, has reached what may well be 

 'regarded as the highest human power that of abstract 

 reasoning; of saying, (i) this is true; and (2) this is true; (3) 

 therefore, this is true. The study of this feature of Zoology 

 is known as Psychology. The lower animals have their 

 psychology as well as man, but it is not so far-reaching 

 nor complex. 



360. The Social Instincts and their Result in Man. In 



the course of our studies we have found many animals 

 that recognize their kind and more or less definitely asso- 

 ciate with them. This reaches a very high plane in the 

 bees and ants. Similar social life is to be found in all the 

 primates, but it is not so well organized as among the ants. 

 In man, even in primitive man, these social instincts 



