In order for the world to become peaceful, people must become more peaceful. Among mature people war would not be a problem - it would be impossible. In their immaturity people want, at the same time, peace and the things which make war. However, people can mature just as children grow up. Yes, our institutions and our leaders reflect our immaturity, but as we mature we will elect better leaders and set up better institutions. It always comes back to the thing so many of us wish to avoid: working to improve ourselves.