60 HEREDITY AND ENVIRONMENT 



have had a development from relatively simple 

 beginnings. All children come gradually to 

 an age of intelligence and reason. In its 

 simpler forms at least reason may be defined 

 as the power of predicting future events and 

 of reaching conclusions regarding unexperi- 

 enced phenomena under the influence of past 

 experience. In the absence of individual ex- 

 perience young children have none of this 

 power, but it comes gradually as a result of 

 remembering past experiences and of fitting 

 such experiences into new conditions. Young 

 infants and many lower animals lack the 

 power of reason, though their behavior is fre- 

 quently of such a sort as to suggest that they 

 are reasoning. Even the lowest animals avoid 

 injurious substances and conditions and find 

 beneficial ones; more complex animals learn 

 to move objects, solve problems, and find their 

 way through labyrinths in the shortest and 

 most economical way; but this apparently in- 

 telligent and purposive behavior has been 

 shown to be due to the general elimination 

 of all sorts of useless activities, and to the per- 

 sistence of the useful ones. 



