CONDITIONS OF PROGRESS 



tire behind the Pyrenees, on the other hand 

 the complete overthrow of the Frankish power 

 would probably have required many battles as 

 fierce as this one. This increased toughness of 

 civilization is still more plainly seen five cen- 

 turies later, when the overwhelming victory of 

 the Mongols at Liegnitz produced no effect at 

 all beyond a temporary scare. It was not that 

 the invasion under Batu was intrinsically less 

 formidable than the invasion of Attila, but that 

 the physical strength of civilized Europe had 

 been growing throughout the long interval, so 

 that the blow which might once have proved fatal 

 was no longer dangerous. Since the fruitless 

 sieges of Vienna by the Turks, the mere dread 

 of barbaric or semi-barbaric invasion has passed 

 away forever. Tribally organized barbarism is 

 henceforth out of the lists entirely, and even 

 the civilization of lower type has ceased to com- 

 pete, in a military way, with the civilization of 

 higher type. 



Thus we see how natural selection, facilitating 

 and cooperating with the integration of the more 

 civilized communities and their increase in size 

 and complexity, has gradually removed one of 

 the dangers to which the earlier civilizations 

 were exposed, and has concentrated the power 

 of making war on a grand scale into the hands 

 of those communities in which predatory activ- 

 ity is at the minimum and industrial activity at 



IS 



