Much has been written as to the gains to civilization from the "intercourse" thus set up between West and East. Gains there were; and if we remember that thus to have gained was the measure of the incapacity of Christendom for peaceful traffic with the world of Islam, we can learn from the process something of real sociological causation. Men who, from ferocity and fanaticism, could not make quiet acquaintance with their neighbours, were hurled against them in furious hordes, generation after generation, and in the intervals of fighting came to know something of their arts and their thought, exchanging handicrafts and products. The crowning irony of the evolution lay in the entrance of unbelief into the Christian world through the very contact with the "infidel" who was to have been crushed. This perhaps was the discovery that disillusioned the papacy. And but for the spirit of faith and hate--the true correlatives in Christian history--every gain from the Crusades might have been made ten times over in commerce. To make such gains at the price of nine million lives and unutterable evil is the contribution of the Crusades to civilization. It is true that from the East the later crusaders learned what chivalry they evolved; that Saladin became a kind of model hero for Christian knights; and that he could hold knightly friendship with Richard of England. But Richard nevertheless could massacre two thousand hostages in cold blood for an unpaid debt; and his crusading left him as it found him, a faithless ruffian, whom to honour is to be cheated by a romance. Nor did passages of chivalry ever root out of crusaders' hearts the creed that no faith need be kept with a misbeliever.