148 The Third and Fourth Generation 



This has been notably true in sex relations 

 and in matters of heredity. Possibly, when 

 little or nothing was known of the laws that 

 govern hereditary phenomena, some trust in 

 luck was excusable, and when knowledge of 

 matters pertaining to sex was tabooed and only 

 clandestinely acquired, about the only recourse 

 was blind dependence on chance. 



If, then, the preceding chapters have accom- 

 plished their purpose, they have left the 

 impression that the young people, who are to be 

 the mothers and fathers of the next generation, 

 have a right to a frank, yet reverent, presenta- 

 tion of reproduction and heredity, at least a 

 presentation sufficient to make them realize 

 that these phenomena are well within the pale 

 of law and order. Now, one may not marry 

 into a family with a persistent tubercular 

 history in the blind hope that luck will prevent 

 the reappearance of the defective tendency in 

 future generations; we know what to expect. 

 We know that insane and feeble-minded stock 

 is prone to reproduce insanity and feeble- 

 mindedness, and that, on the other hand, 



