We will forget.Researchers have long found that the memory of epochal events fade with time. The remembering of such events even has a specific name

flashbulb memory. As time passes, the chronology gets jumbled up; we fumble on the details; we airbrush some parts and highlight others. We re-imagine the past to make it more coherent, meaningful, bearable. One ongoing study at the University of Illinois Chicago’s Psychology Department – of a large, country-wide sample of people – is finding out that we have already forgotten some things about September 11. How much time between the first and second plane? Which tower fell first? What was the flight number of the second plane? Was the Pentagon hit after both World Trade Center Towers? We forget. We conflate. We confuse.

But we also know, of course, that this kind of memory is not the most important one. Some events solder themselves into our consciousness so intensely that they change the way we see the world for ever. The details barely matter. The change itself matters. Your child is killed in a car accident; your mother is diagnosed with breast cancer; your best friend betrays you; your wife is raped. These kinds of events stop your life for a moment; your soul freezes while the rest of the world swivels around you to a new position. Part of you insists: this hasn’t happened. Part of you demands: move on. Most of you knows that neither is an option.

And most of us know that there is no moving on from September 11. It wasn’t a random tragedy for which grief is a slow-acting salve. It was a massacre – a cold-blooded, fanatical murder of civilians by men possessed by a theocratic ideology. It was an invasion – the violation of sovereign American soil, the erasure of a visible monument to American success and energy and civilization. It was a crime – the filling of the air of a great city with the irradiated dust of innocent human lives. It was a statement – that radical Islam intends to attack and destroy the very principles of the Enlightenment that underpin the American experiment – freedom of religion, of conscience, toleration and secularism. The appropriate response to this act of nihilism and evil is therefore not grief or remembrance or sadness or reflection, although each of those has its place. The appropriate response is rage.

For whatever else September 11 was, it was a declaration of war. That war continues. The totalitarian force of fundamentalist Islam, like the forces of Nazism and Communism that preceded it, has not disappeared. We briefly defanged it in its most important lair in Afghanistan, but even there, it has not been extinguished. Saudi Arabia, the chief exporter of this murderous ideology, remains protected by the West. Saddam Hussein is currently laboring to manufacture weapons of mass destruction which his allies in the Islamist terrorist network would dearly love to use on American soil. The United Nations and much of the civilized world would rather let him do so than face the risks of taking him on. Suicide bombers – ideological comrades of the twisted sociopaths who flew planes into the World Trade Center – have not relented in attempting to destroy the democratic state of Israel. Anti-Semitism, now as in the past a core of the totalitarian mind, has metastasized like a cancer throughout the Middle East and back into its ancient home in Europe. Educated men and women who regularly find the slightest fault in democratic Western societies, vie with each other to provide excuses, justifications and rationalizations for the murderous tyrannies and blood-thirsty mobs of the Arab Middle East. In a welter of arguments, articles, op-eds and books, intellectuals are eagerly laying out the case that the murderers of 9/11 died for an explicable and justifiable cause, that the West itself is in part responsible for what was unleashed against it, that war can be avoided, that there is nothing but shades of gray in this complicated world.

But through all this, we know what that day showed us. It really wasn’t complicated. That day showed us that we stand deeply vulnerable to a destructive force in some ways more dangerous than even the last two totalitarian powers Americans were called on to defeat. This enemy refuses to fight with honor; it kills civilians not as a by-product of fighting but as an end in itself; it hides and disappears and re-emerges whenever its purposes are served; it may soon have access to weapons that Hitler and Stalin only dreamed of. But it cannot be defeated the way Nazi Germany and Communist Russia were defeated because it is more like a virus than a host, infecting and capturing nation-states, like Afghanistan, and then moving on to others. September 11 showed Americans that for the first time in their history, they stand vulnerable to that force in their homeland. War has been brought to them. And, deep in their hearts, they know it.

That’s why I think that, for all the return to superficial normality, Americans really have changed. The illusion of isolationism has been ripped apart. How can America opt out of the world when the world refuses to leave America alone? The illusion of appeasement has been destroyed. Do we really think that by coddling regimes like Iraq or Syria or Iran or Saudi Arabia, we will help defuse the evil that lurks in their societies? The illusion of American exceptionalism has been shattered. The whole dream of this continent – that it was a place where you could safely leave the old world and its resentments behind – was ended that day. The proliferation of flags that day and subsequently was not a function of jingoism. It was the display of a symbol whose meaning had just been changed for ever. The inviolability of America had been destroyed. And the display of Old Glory was a signal not of blind patriotism but a way to show the world and the enemy that we loved it still and passionately, and that we were prepared to fight to restore its honor. A whole generation will grow up with this as their most formative experience – a whole younger generation that knows that there actually is a right and a wrong, and that neutrality is no longer an option. That generational power has only just begun to transform the culture. In decades’ time, we will look back and see what a difference it made.

And if we need to humanize this, perhaps we should leave our own memories of that day behind and think of those wives and husbands and children and parents who cannot live a single day without remembering. For them, normality can never return. Every evening when a father doesn’t come home, every birthday when a card cannot be sent, every Christmas when a child’s mother is no longer there is a rebuke to the very idea of our broader forgetfulness. They are symbols of our wider collective wound, goads to us when we falter in the fight back, emblems of the free society that this new enemy is determined to destroy. To paraphrase Bruce Springsteen, everything is everything and they are still missing. And they demand that our vigilance never end.