2 The Third and Fouexh Generation 



import are hazy and misleading. It seems wise 

 therefore to present the new data simply that 

 as common knowledge they may become a basis 

 of wise individual conduct and may help mold 

 public opinion on some important social ques- 

 tions. 



This book is intended primarily for young 

 people. They can most readily break away 

 from the whims and prejudices of the past and 

 adopt a new set of ideas as adequate grounds for 

 new habits. They live only in this scientific 

 age when we have an increasing respect for facts, 

 reason on them to correct conclusions, and base 

 on them our sense of duty. They are practical 

 optimists, and what seems an impossible dream 

 of the visionary to an older generation, hide- 

 bound by preconceived notions and social 

 traditions, comes to be, for valorous youth, a 

 simple accomplishment dictated by good sense. 



It has been the aim to make the presentation 

 as simple and non-technical as possible. So 

 many of the concepts dealt with are rather new 

 to the average reader that some of the chapters 

 at least will need study rather than mere read- 



