xiv Preface 



tioii In a particular science is requisite to make a highly 

 successful reader even in that science. 



So far, then, as I am able to pass upon my own quali- 

 fication for making such use as I have made of biochemistry, 

 it is a question of whether I have a sufficient ground-work 

 of formal training to make me a safe chooser among authori- 

 ties and estimater of the significance of their results. 



Although my chemical practice was limited to three years, 

 one of these as a student assistant, so much did I live in the 

 laboratories during that period, that even to-day the open- 

 ing of a book or journal on chemistry seems to fill my nose 

 with foul though pleasantly reminiscent odors and to en- 

 crust and stain my fingers with diverse corrosives — all of 

 which may mean that I was more a musser in chemicals than 

 a real student of chemistry. Nevertheless I verily believe 

 the experience enabled me to be a more intelligent reader of 

 chemical writings. 



As for the science of mind, I am obliged to own that I 

 have never spent a day in an experimental laboratory of 

 either animal behavior or human psychology. But I own 

 also that for this I am not regretful if such defect of train- 

 ing be an essential condition of escape from the narrowing 

 of interest in and conception of "behavior" which has at- 

 tended later work in this field. I do not believe, however, that 

 tliis is the only way of such escape. Zoologists must realize 

 before long, I am quite sure, that laboratory experimentation 

 in animal behavior can be only a rather minor agent for the 

 task of understanding the psychical life of the animal world 

 as a whole. 



This leads to the remark I wish to make about the discus- 

 sion of psychic integration in the last chapters of this book. 

 One of the most important things accomplished by that dis- 

 cussion is, I estimate, the calling attention to the tendency 

 of instinctive activity to excessiveness over the actual needs 

 served by the activity. Why has this truth (for there can 



