474 TEADITION AND HEKEDITY 



It is at least apparent how difficult a problem is the judgement 

 to be passed on the effects of modem differential fertihty. There 

 are grounds for thinking that those who see in differential fertility 

 the cause of the cyclical course of civiHzation both over-estimate 

 the results and neglect certain aspects of the changes involved. 

 Differential fertility is not a factor to be disregarded ; the results 

 which it is now producing demand the most careful investigation. 

 Nevertheless, so far as our knowledge extends, we should view 

 it rather as the result than as the cause of the cyclical course of 

 history — the course which historical changes take being due 

 primarily to changes in tradition. This conclusion is in harmony 

 with all that has been said in this chapter as to the relative 

 importance of change in tradition and of change in the germinal 

 constitution. From the first period in history changes in tradition 

 have come to override changes in the germinal constitution ; 

 the latter form of change is far from being negligible, but it is 

 a contributory rather than a fundamental cause of the events of 

 history. 



