viii PREFACE 



guide to conduct and resent the intrusion of seem- 

 ingly new standards. Others uninfluenced by reli- 

 gious training are of the opinion that philosophic 

 considerations are useless and that every human 

 being has to work out his own salvation by personal 

 experience. Both these attitudes seem to me sin- 

 gularly unimaginative and unidealistic. For if it is 

 true that human beings are no exception to the rule 

 that all organized beings are in the process of adap- 

 tation to their surroundings, is it not evident that 

 the chief aim of conscious beings should be the intelli- 

 gent and artful adaptations of each individual to his 

 special group of conditions? But how is that pos- 

 sible without some understanding of the larger prin- 

 ciples operative in the control of the body? It 

 will not suffice to say that every person, by taking 

 a common-sense view of life or a religious view of 

 life, will learn to act for the best. The truth is that 

 human problems are extremely complex and that 

 knowledge is required to solve them. History has 

 richly supplied us with instances of the ways in 

 which religious teaching has been appealed to in 

 solving human questions; it has also supplied us 

 with sufficiently numerous examples of what happens 

 when untrained people have been guided by precon- 

 ceived ideas or have depended on opportunism and 

 personal desire. The results, it seems to me, have 

 not been so satisfactory as to make one feel that 

 other guides to conduct can be pushed aside as 

 unnecessary. The biological idea of human life is 



