omorrow, Americans will try to return to normal. This is a resilient country, and even in New York City, most citizens have already chosen to go back to their regular routines as quickly as possible. In general, we are not a people that spends much time looking back. "Move on" is practically the national mantra.

This is commendable and indeed necessary in view of the alternative: a capitulation to fear and despair that the terrorists must surely have hoped for. There has been no finer rebuke to their pretensions than America's determination to press on.

But the normal we are returning to is different from what we knew a week ago. Tuesday's tragedies were not only unifying but clarifying. Americans now live a state of war against an irrational, vengeful and elusive enemy. And if we are to win, we will have to become used to the idea that we are in this for the long haul. Coming to terms with that new reality, winning this war, will require discipline, stamina and sacrifice.

For years now, younger Americans have yearned to prove that they are as patriotic and as capable of self-sacrifice as the Greatest Generation. The commitment made after Pearl Harbor was both larger and simpler than the one we are being asked to undertake. Back then, the aim was clear, the path was obvious, and the sense of solidarity was natural for a country that had to focus single-mindedly on winning World War II.

Our shared mission, to eradicate terrorism, is a noble one. The rewards for victory would be immense ・a safer world and a planetary commitment to cooperation and tolerance. But our individual tasks are vague. President Bush is unlikely to reinstate the draft or impose rationing. We will go about our ordinary jobs as before. Buying consumer goods is not only possible, it has been elevated to a virtual act of patriotism to aid a flagging economy. Nevertheless, we will need to make sacrifices that are all the more difficult because they are unseen and require more patience than heroism.

American resilience, which allows us to bounce back from setbacks, forgive old enemies and rewrite our national story for every generation, has a downside. Some may call it a short national attention span. Yesterday's crusade is tomorrow's inconvenience. The gas crisis that was supposed to commit us to energy conservation quickly gave way to the S.U.V. era. People who willingly stand in lines to get through airport security this month may not be so understanding by the Thanksgiving holidays.

Terrorist hijackings or airline explosions in the past have led to periods of tighter airline security, followed quickly by periods of relaxation and colossal carelessness. What should be clear now is that the days of relatively unhindered air travel, with curbside check-ins and all the rest, are almost surely gone and that a period of considerable inconvenience is upon us.

Our politics are going to have to change as well. It has been a very long time since American officials told their constituents that they would have to make some sacrifices for the common good. But that will almost surely be the case if we are going to transform our defense and intelligence systems from cold war monoliths to agile, inventive organizations that can detect and defeat terrorists. Some obsolete bases will have to be closed, and defense contracts that provide profits and jobs to key Congressional districts will have to go by the wayside. The laundry list of promises candidates made in the last election will have to be trimmed.

Perhaps most painful of all, America may have to give up the post-Vietnam illusion that it is possible to fight wars with few casualties. Our success in the Persian Gulf and even our limited achievements in the Balkans created the illusion that American military technology is sophisticated enough to be used in combat without putting soldiers in harm's way. But what we have actually been enjoying is an extended string of luck. Last week, the message came through loud and clear that luck can run out.

Washington must be changed, as well as the rest of the country. The response of previous administrations to terrorism abroad ・the 1996 Khobar Towers bombing in Saudi Arabia, the embassy bombings in Africa two years later, the attack on the U.S.S. Cole last year ・has been much like the nation's airline security policy: fitful, short-lived and not terribly effective. If our people have a short attention span, it is probably because their leaders do.

Over the past week, Americans have contemplated the great divide that separates life before the hijacked planes plowed into the twin towers and the Pentagon with life after. The unspoken presumption seems to be that we have experienced a loss that stretches beyond the thousands of lives that fell victim to the terrorists. There has been a sense that whatever comes next must naturally be diminished.

That need not be true. As many candidates pointed out in the last election, Americans desperately want to commit to something greater than themselves. That was the secret of what we admired in the World War II era, and it is what this new war against terrorism will require as well. The awful week of death and destruction that has just ended might be the invitation to create a great new generation and a finer United States.

To get there, we must be careful to protect the core of our national culture, to remember that we are fighting not for a flag but for a system of beliefs that includes our basic civil liberties and an unyielding tolerance. Social conservatives who have been speculating that the destruction of the World Trade Center was punishment from a God grown angry at abortion and homosexuality are rushing in exactly the wrong direction. The people who gathered at various prayer services around the country last week represented not only different races and creeds, but different social agendas and political outlooks. By their very coming together, they showed their belief in a world in which no one believes that God's face is turned implacably against any human being.

We wake up tomorrow and take one more step down a new and very long path. But the promise at the end can be worth the journey.