It is tempting to hope that the 10th anniversary of the Sept. 11 attacks will serve as a cathartic moment, allowing Americans to turn a page on the worries and errors of the last 10 years without diminishing the successes. But history has no pages.

Instead, as we head into the decade after the decade after, our goal should be to look at global terrorism with a sharp eye and a clear head.

The coarseness that marked aspects of U.S. conduct in the world after Sept. 11 -- including a sometimes tragic disregard for the rights of innocents ensnared in a global war against terrorists -- may be understandable. However, much of the world, including many Americans, concluded that it was not excusable. And as the trepidation over another attack receded, the rough edge of American fear was too easily turned inward, with domestic politics assuming a sometimes vicious tone.

Over more than two centuries, American democracy has shown a talent for self-correction. Time and again, moral shortcomings have been confronted and our society elevated; political excesses of right or left have been supplanted by reason and moderation; an instinct toward adventure or overreach has been overcome. The memory of those who died is eternal, but the shadows of 9/11 are not. In the midst of a global economic crisis rises an Arab Spring and new hopes.

The threat of Islamic extremism did not die with Osama bin Laden. Vigilance, judiciously practiced, is still required. Those who would do the U.S. harm will continue, to the best of their dwindling abilities, to find the chinks in our armor. There will be more attacks against the U.S. and its interests, at home and abroad, and some will succeed.

This is a fact we must accept, as hard as that may be for citizens of a free and democratic nation. In a metaphor borrowed from Philip Zelikow, who was executive director of the 9/11 commission, we know that very occasionally a passenger airplane will malfunction and fall from the sky, yet we keep on flying, because we look at the big picture, judge the odds and have trust in the system we have created and continually improve.

This nation has faced a decade-long test of its values, governance and role in the world, with mixed results. Americans have shown great resilience, and with renewed moral force, our full faith in ourselves and our institutions will be redeemed. That, our enemies know, is the ultimate victory.

To contact the Bloomberg View editorial board: view@bloomberg.net.