1 64 EVOL VTION AND NA TURAL THEOL G Y. 



through the world like a fire in 1348, and broke 

 out again and again during the remainder of 

 the century, depopulating every country in the 

 known world, those least severely visited losing 

 half their inhabitants, and those most so, nirie- 

 tenths. There is even some reason to think 

 that it visited North America also. But no 

 sooner had the pestilence subsided, than it was 

 followed by an unusual number of births, and 

 the gaps in the population were soon filled up. 

 Looking at the history of Europe before and 

 since, it appears by no means unlikely that the 

 unparalleled progress of Modern Europe for 

 the last 500 years may be due in great part to 

 the destructiveness of this plague.* Only the 

 strongest and healthiest would have had the 

 remotest chance of surviving so terrible an era, 

 and they would thus become the progenitors of 

 a much stronger race, both in body and mind, 

 especially when their descendants became more 

 numerous, and were again obliged to compete 

 with each other in the struggle for existence. 

 The weaker members of the population being 



* It may also have assisted to counteract the baneful influence of re- 

 ligious persecutions and celibacy. 



