As a result of the constant attacks by the Vikings and other nomads, the governments of Europe were constantly under attack. Communities did not feel that their governments were providing adequate protection for them against outsiders. The economies of Western Europe were in shambles, and trade routes were disrupted.
As the monarchs of central governments lost power, a new type of government evolved called Feudalism. Feudalism began in France around 900 A.D., and spread throughout the remainder of Europe within 150 years.
To do for the world more than the world does for you--that is success.
Medieval knights put shark skin on their sword handles to give them a more secure grip.