210 ENVIRONMENT 



the forests of Northern Europe, would ever have 

 emerged from barbarous simplicity had they 

 remained unaffected by outside influences. But 

 they possessed energy which could resist the 

 gloom of their environment, and, touched by the 

 glow of Roman civilization, they assimilated 

 knowledge and imitated accomplishments which 

 speedily gave them the command of Nature. 

 The birthplaces of agriculture, and of civilization, 

 have been treeless valleys. Such are Egypt and 

 Mesopotamia, the expanses of Northern India 

 and the densely inhabited portions of China. 

 Far away across the ocean there were two other 

 centres, the treeless upland valleys of Mexico 

 and Peru. In all these localities cultivation 

 reached a high pitch of efficiency. 



But the regularity of an agricultural life 

 may fatally reinforce the growth of habits. 

 Agriculturists are generally conservative in their 

 opinions. Under a tropical sun, more espe- 

 cially, the spirit of changefulness cannot survive 

 the cramping effect of custom : the people 

 become so inured to the monotony of peace as 

 to be unable to rise to the exigencies of war, 

 and helplessly suffer their fields to be trampled 

 by the feet of restless invaders. Hordes of 

 these have been bred on the grazing lands which 

 lie along and across the valley horizons. Pasture 

 must be searched for over vast areas of country 

 at different seasons of the year, and a pastoral 

 life nourishes the spirit of adventure by its hard- 

 ships and its constant vicissitudes. The Hebrews 

 were trained for the conquest of Palestine by 

 their wanderings in the desert. Egypt has con- 

 stantly been overrun by Bedouin tribes, India 

 and China by Mongol races which have swept 

 eastwards and southwards from the steppes of 

 Tartary and Siberia. In our own time we have 



