In his article Elrod concentrates on an issue which was indeed vital to the Habsburg empire: the central idea of the pentarchy's international policy. At the Congress of Vienna, held after the end of the Napoleonic wars, the policy of the victorious powers was primarily oriented toward maintaining a balance of power and accepted the concept that the Great Powers were jointly responsible for keeping the peace. By the middle of the century at the latest there was an obvious change in motivation, for, under the ever increasing impetus of new ideas and new people, changes now came to be measured primarily on the basis of self-interest and only secondarily on the basis of their effect on international stability.