A couple of years before he died, the diplomat Richard Holbrooke wrote: “The United States is still great. It deserves leadership worthy of its people, leadership that will restore the nation’s pride and sense of purpose. That task must begin at home, but the world will be waiting and watching.” (Foreign Affairs, September/October, 2008.)

Holbrooke began his diplomatic career with a tour in Vietnam. Later, after he left the U.S. Foreign Service, various presidents called on him to perform hard tasks. The most famous were the 1995 Dayton peace talks that ended the Balkan wars.

He understood what it meant when the United States no longer won decisive victories. He was serving, even as he died, as the government’s point man on Afghanistan. He knew the limits of our power in a world where other countries were becoming strong and prosperous, too.

The complexity of today’s world means a few individuals can cause havoc. Terrorist attacks or the ending of a dictator’s power by crowds inspired through social networking—the rules have changed since the battles of the twentieth century.

The mighty British empire over two centuries ago was unable to force a ragtag bag of American colonials to do what it wanted. It wisely left the fray and allowed its former colony to go its own way.

We still have power, but we need wisdom in the use of that power. We first need to strengthen our institutions at home, to see that ordinary people can build decent lives. We win more permanent battles by the moral influence we possess than by our weapons.