214 Heredity and Environment 



emphasis was placed upon influences of environment in phylogeny 

 and ontogeny. From the earliest times it has been believed that 

 species might be transmuted by environmental changes and that 

 even life itself might arise from lifeless matter through the in- 

 fluence of favorable extrinsic conditions. If environment could 

 exert so great an influence on the origin of species or even of 

 life itself much more could it affect the process of development of 

 the individual. It is still popularly supposed that complexion is 

 dependent upon the intensity of light, and stature upon the quan- 

 tity and quality <of food, that sex is determined by food or tem- 

 perature, mentality by education, and that in general individual 

 peculiarities are due to environmental differences. 



Many philosophers of the seventeenth and eighteenth centur- 

 ies taught that man was the product of environment and educa- 

 tion and that all men were born equal and later became unequal 

 through unequal opportunities. Decartes begins his famous "Dis- 

 course on Method" with these words: 



"Good sense is, of all things among men, the most equally dis- 

 tributed . . . The diversity of our opinions does not arise from 

 some being endowed with a larger share of Reason than others, 

 but solely from this, that we conduct our thoughts along different 

 ways, and do not fix our attention on the same objects." 



Similar views were expressed by Rousseau and Diderot, and 

 especially by John Locke and Adam Smith. The Declaration 

 of Independence merely reflected the spirit of the age in which 

 it was written when it held this truth to be self evident, "that 

 all men are created equal." The equality of man has always 

 been one of the foundation stones of democracy. Upon this 

 belief in the natural equality of all men were founded systems 

 of theology, education and government which hold the field 

 to this day. Upon the belief that men are made by their en- 

 vironment and training rather than by heredity are founded most 

 of our social institutions with their commands and prohibitions, 

 their rewards and punishments, their charities and corrections, 

 their care for the education and environment of the individual and 



