MENTAL EVOLUTION 137 



American continent, and effectually severed all communication 

 between the Old World and that portion of the New which had 

 hitherto been visited." (Rogers, "History of Agriculture and 

 Prices in England," vol. 1, pages 292 ff.) 



In China it is said that the plague destroyed 13,000,000 people. 

 It probably destroyed as many more in other parts of Asia. 

 Fifteen years after its inception, that is, in August, 1348, it 

 reached England at the opposite end of the great land mass of 

 the eastern hemisphere. There and in France and Italy it ap- 

 pears to have slain a third of the population. Its ravages were 

 worst among the common people, but even the king's daughter, 

 Joan, died of it. The way in which it swept people away may be 

 judged from the fact that the bishop's registers of the diocese of 

 Norwich show that in many parishes three or even four vicars 

 were installed within eighteen months. Not till 1368 did the 

 plague finally disappear from England. 



I have dwelt on the Black Death because of the way in which 

 the accounts of this disaster combine three great types of phe- 

 nomena. One type pertains to climate, one to earthquakes and 

 volcanoes, and one to disease. That they were connected in the 

 way supposed by the people of the fourteenth century is not to 

 be supposed. Nevertheless, it seems clear that all three rose to 

 a maximum in the first half of that century. I shall not attempt 

 to show how volcanoes and earthquakes were concerned with the 

 others, although I believe that probably they owe their origin to 

 the same causes as the climatic phenomena. As to disease and 

 the weather the connection is clearer. It will be remembered that 

 the plague first came into prominence in China in 1333. This 

 was in the decade succeeding the coldest known winter in north- 

 western Europe, one of the driest seasons in England, the fastest 

 growth of the Big Trees in California, and the most rapid rise 

 and highest level of the Caspian Sea. These manifestations of 

 climatic instability were accompanied by excessive storms and 

 floods in China. In countries like China the plague seems always 



