This, in a very general way, is what happened during the centuries which followed the Crusades. It was a slow process, this gradual shifting of power from the castle to the city. There was some fighting. A few tailors and jewellers were killed and a few castles went up in smoke. But such occurrences were not common. Almost imperceptibly the towns grew richer and the feudal lords grew poorer. To maintain themselves they were for ever forced to exchange charters of civic liberty in return for ready cash. The cities grew. They offered an asylum to run-away serfs who gained their liberty after they had lived a number of years behind the city walls. They came to be the home of the more energetic elements of the surrounding country districts. They were proud of their new importance and expressed their power in the churches and public buildings which they erected around the old market place, where centuries before the barter of eggs and sheep and honey and salt had taken place. They wanted their children to have a better chance in life than they had enjoyed themselves. They hired monks to come to their city and be school teachers. When they heard of a man who could paint pictures upon boards of wood, they offered him a pension if he would come and cover the walls of their chapels and their town hall with scenes from the Holy Scriptures.