XU PREFACE 



in art, in morals, in sociology, or in science, bears 

 an extremely close relationship to biology and its 

 concepts. It may be that this fact is quite well 

 understood by many of the worthiest representatives 

 of these subjects, but my personal acquaintance with 

 cultivated and creative persons has made the im- 

 pression that it is only here and there that the modern 

 biological spirit has been recognized as a powerful 

 inspiration. My own faith is so strong in the direc- 

 tive value of a serious biological conception of life, 

 that I offer this essay, hoping its spirit may evoke 

 a sympathetic response in those who, like myself, 

 are striving, not without pain, to find a more con- 

 sistent guide to those complicated personal reac- 

 tions which we call conduct. 



