RATS AND MEN 351 



kind of function, though the steps by which it was 

 fashioned can probably be traced, just as we have 

 already succeeded in charting in outline the progres- 

 sive elaboration of the neurologic mechanisms em- 

 ployed. 



The revolutionary nature of the change in be- 

 havior patterns colligated with the appearance of 

 symbolic thinking can hardly be exaggerated. Once 

 this change has been consummated, habitude as the 

 dominant behavior pattern gives way to insight in 

 terms of generalization of experience, foresight of pos- 

 sible future consequences of action, the fabrication of 

 consciously directed purposes, deliberative choice in 

 view of these purposes, and finally the development of 

 ideals of character and the shaping of daily conduct 

 with a view to molding the personality in conformity 

 with these ideals. 



We have not the slightest evidence that these 

 powers are possessed in any degree by any of the 

 lowest mammals, though we can see, very dimly, their 

 sources and we can trace some of the stages in their 

 elaboration. They seem to have grown up within that 

 capacity for individually modifiable behavior which 

 is a common feature of all living things (Herrick, 

 1924, chap. xix). 



Our contention, then, is that certain functions 

 which we know best introspectively are realities of 

 experience and as such are susceptible of scientific 

 study as well as of practical use. There is nothing to 



