PREFACE ix 



In the social evolution of the human mind, 

 the deepest desires of the individual have been 

 often necessarily sacrificed to the needs of the 

 group. Sometimes they have been unneces- 

 sarily sacrificed, since human intelligence is, 

 unfortunately, not omniscient. Nevertheless, 

 the sum total of human knowledge has now 

 become great enough so that it is at least well 

 to pause and take account of its bearing on the 

 age-old problem of family life, in order that 

 our evolution henceforth may be guarded by 

 rational control rather than trial and error in 

 so far as is possible. Such a summarization of 

 our actual knowledge of the biology, sociology 

 and psychology of the foundations of the family 

 institution this book aims to present, and if it 

 can at the same time suggest a starting point 

 for a more rationalized system of social 

 control in this field, its purpose will have been 

 accomplished. 



The Authors. 



