RETROSPECT AND PROSPECT 381 
at least, we may well ask with E. Carpenter, “‘Is Civilization a 
disease?” If it is a disease it is one which has apparently proven 
fatal to many nations in the past. Without venturing to discuss 
the various explanations of the downfall of civilizations it may be 
said that, so far as insight can be obtained in the racial changes 
that have accompanied this process of decay, the ethnic stocks 
which were responsible for the cultural advancement that oc- 
curred became gradually bred out and replaced by the blood of 
alien peoples. Decadence from within was often the prelude to 
conquest from without, but whether the old stock was replaced by 
conquering invaders, peaceful immigrants, or the progeny of 
slaves, the result was in many respects the same. 
In the present book we have made what is perhaps a very 
inadequate effort to diagnose some of the racial maladies that 
affect our own day and generation. It is only by recognizing these 
and understanding the methods of their working that effective 
means can be taken to keep them in check. Rather feeble at- 
tempts have been made to curtail the propagation of mental 
defectives, through sterilizing or segregating some of the worst of 
these undesirable elements. This practice carried on much more 
extensively than it has been would undoubtedly relieve society 
of an immense burden. But the elimination of our worst defec- 
tives would not meet the most serious difficulty which consists in 
the loss of those stocks which carry our best inheritance. It is 
doubtful if the pecuniary rewards which have sometimes been 
advocated for increasing the birth rate of desirable parents 
would prove very effective. There is much to be said in favor of 
making parenthood voluntary in all classes so as to restrict the 
birth rate among the people who occupy the rather broad belt 
between the obviously defective and ordinary mediocrity. This 
of itself would lead to a greater relative fecundity among those of 
superior inheritance, and so long as restriction is not carried far 
enough to prevent all increase of the population, the result would 
doubtless be eugenically and socially desirable. Through reduc- 
ing the death rate the natural increase of several countries has 
become more rapid, despite the diminishing numbers of births. 
