Certainly, protecting oppressed people, stopping ethnic conflict and promoting responsible governance are worthy goals. But none is as important for American security and prosperity as keeping the peace in the Middle East, Europe and East Asia.

Inequality of any kind, once considered a normal, natural part of human existence, came to be seen in the course of the twentieth century as increasingly illegitimate.

If architecture is, as is sometimes said, music set in concrete, then football and basketball may be said to be creativity embodied in team sports.

The attacks of September 11, 2001, were spectacular, riveting, grim, costly and searing. The shock that they caused reverberated throughout the world. What happened in New York and Washington and Pennsylvania ended the lives of thousands of people and changed the lives of many more. But they did not change the world.

While analogies are useful, however, they can also be misleading. They smuggle in assumptions that can be wrong.

To call the American role in the world imperial was, for many who did so, a way of asserting that the United States was misusing its power beyond its borders and, in so doing, subverting its founding political principles within them.

Certainly, protecting oppressed people, stopping ethnic conflict and promoting responsible governance are worthy goals. But none is as important for American security and prosperity as keeping the peace in the Middle East, Europe and East Asia.