Historical lessons are more like tea leaves than neon signs, so anyone who claims to see one clearly had best look again. My own imperfect vision conjures up two distinct pictures, one farsighted and one nearsighted.

The farsighted view suggests that our current national trauma is less ominous than several earlier challenges, to include the American Revolution, the Civil War, and the Great Depression. The fate of the American republic is not really at risk. As the shock of those horrible scenes subsides, history will restore a sense of proportion.

The nearsighted view, based on our own experiences during the Cold War, suggests that we should avoid making the campaign against terrorists into a moral crusade in the Evil Empire mode. That approach inevitably releases domestic demons of its own making and, with its rhetoric of limitless convictions, tempts us into military commitments we cannot keep.

In short, we need to be confident and we need to be careful. The former view is rooted in our resilience and longevity. The latter is rooted in our innocence as a recently arrived world power. If we manage to put both pictures together, we shall at last be capable of irony.