72 THE WAY LIFE BEGINS 



A second factor is the existence of self-conscious thought in 

 human beings and the play of this thought upon the repro- 

 ductive instincts. Further reference to this factor will be 

 made in the next chapter. It is sufficient here to recall that 

 thought, including, of course, memory, has the power of 

 greatly modifying the instinctive sex behavior of man. This 

 may take the direction of sexual degeneration or perversion, 

 on the one hand, or of restraint and of a reduced birth rate 

 on the other. The conflict of thought and instinct operating 

 under the conditions of civilization, introduces the most 

 serious problems in human life. 



