CONCLUSION 477 



the fact that, whenever we can catch sight of the emergence of 

 prehistoric races into the light of history, we find one or other 

 of these factors to have been present. Further there is every 

 reason to suppose that normally such of these factors as are in 

 use are effective and that therefore in the first and second periods 

 of history some approximation to the optimum number was 

 normally attained. 



The third period is in many respects different from those that 

 preceded it. In the first place the number desirable has been 

 constantly increasing, so much so that increasing numbers are 

 taken as being a normal feature of human society whereas, 

 in fact, numbers throughout human history as a whole have 

 been stationary. It may be that we are nearing a time when 

 numbers will be again normally stationary, for though increase 

 may remain economically desirable, it may cease to be so from 

 a wider point of view of human welfare, when, that is to say, 

 facts other than income per head are taken into account. In 

 the second place there have been frequent failures to attain to 

 the optimum number owing to the many disturbing influences 

 at work. Chief among them are the fluctuations in the number 

 desirable, the erratic action of certain causes of elimination, such 

 as war and disease, and migrations." 



Eegarding the quantitative problem as a whole, it is evident 

 that the necessity of solving it has had the most profound effect 

 upon all societies at all times. It bears directly upon the relation 

 between the sexes around which so largely centres human welfare 

 and upon the most intimate and most valued aspects of the life 

 of every adult those connected with the family. In the past 

 the solution has been unconsciously or semi-consciously achieved ; 

 it has now come within the power of mankind after a due con- 

 sideration of the position deliberately to decide what the best 

 solution may be. 



4. Turning now to the problems of quality, we found that 

 change among species in a state of nature, and therefore among 

 our pre-human ancestors, was due to germinal change alone. 

 Just as man has moved away from the position in which all 

 species in a state of nature are situated as regards quantity, 

 so he has moved away from the position in which they are placed 

 as regards quality. Human history, in other words, is not explicable 

 as due to germinal change alone. Tradition becomes a factor 



