Heredity and Environment 



lives in the midst of intellectual, social and moral stimuli which 

 are potent factors in his development. By means of his power 

 to look before and after, he lives in the future and past as well as 

 in the present; through tradition and history he becomes an heir 

 of all the ages. The modifying influences of all these environ- 

 mental conditions on personality are very great. Each of us may 

 say with Ulysses : "I am a part of all that I have met." So great 

 is the power of environment on the development of personality 

 that it may outweigh inheritance; a relatively poor inheritance 

 with excellent environmental conditions often produces better 

 results than a good inheritance with poor conditions. Of course 

 no sort of environment can do more than bring out the hereditary 

 possibilities, but on the other hand those possibilities must re- 

 main latent and undeveloped unless they are stimulated into 

 activity by the environment. 



Functional activity or use is one of the most important factors 

 of development. Functional activity is response to stimuli, which 

 may be external or internal in origin. The entire process of de- 

 velopment may be regarded as an almost endless series of such re- 

 sponses on the part of the organism, whether germ cell, embryo or 

 adult, to external and internal stimuli. It is a truism that use 

 strengthens a part and disuse weakens it; it is likewise a truism 

 that responses which are oft repeated become more rapid and 

 more perfect, and in this way habits are formed. Practically all 

 education, whether of man or of lower animals, consists in habit 

 formation, in establishing constant relations between certain 

 external or internal stimuli and certain responses of the organism. 

 At first these stimuli are largely of external origin ; later the ex- 

 ternal stimuli may be replaced more and more by internal ones ; 

 but whatever the source of the stimulus the response of the or- 

 ganism to these stimuli is one of the most important factors of 

 development, whether of the body or of the mind. 



The influence of environment upon the minds and morals of men 

 is especially great. To a large extent our habits, words, thoughts ; 

 our aspirations, ideals, satisfactions; our responsibility, morality, 



