Hard to believe it is 20 years today since 9/11. Those few hours when it felt like the security of the world was teetering on its foundations are seared in the memory. It's equally hard to believe that 20 years ago yesterday the bright new millennium hadn't been clouded by a maniacal mission in the name of a religion.
Now, we are almost not surprised that a malcontent in our midst shouted an Islamic incantation as he ran amok with a knife in an Auckland supermarket. Appalled but not really surprised. Every other Western country has experienced something like this.
We're more astonished to learn that guardians of our security knew he would do something like this and couldn't lock him up. We might never know whether he was inspired by recent events in Afghanistan.
President Joe Biden was planning to mark today's anniversary with the orderly withdrawal of the last American forces from Kabul. He'd scoffed at warnings we could see a repeat of the fall of Saigon.
"The Taliban is not the North Vietnamese army," he said. "They're not remotely comparable in terms of capability. There's going to be no circumstance where you see people being lifted off the roof of the embassy of the United States from Afghanistan."
President Biden is turning out to be pretty bad. Not Trump-bad, he doesn't disgrace the dignity of the office. But he hasn't undone some of the foolish things Trump did, like reneging on the nuclear deal with Iran and doing a soft deal with the Taliban to get out of Afghanistan.
Like Trump, he seems to believe the way to deal with the rising power of China is to protect American industries and technology from Chinese competition the way China protects its own. Leadership that has lost sight of the enterprising zest that made America great is turning the 21st century into a story of America's decline.
Twenty years ago Osama bin Laden provoked the bear because he calculated the bear would blunder about in retaliation and thereby advance the jihad he and other young Islamic nationalists were planning. America played right into their hands.
Not content with closing al Qaeda camps in Afghanistan and removing the Taliban from power, President George W. Bush decided it would be a good idea to change the regime in Iraq too. He imagined the removal of Iraq's dictator would spark an outbreak of democracy in the Middle East.
Much later there was a brief "Arab Spring" but, to the disappointment of liberal democrats everywhere, voters in just about all Islamic states elected religious parties to power. Those parties were soon displaced by military coups but there can no longer be any doubt that religion and politics are inseparable in the minds of most people in the Islamic world.
Islam seems to me to be their nationalism. They find their primary identity in their religion in the same way Westerners find it in a nation. The jihadi fringe is the frustrated nationalism that feeds itself by turning the world against it.
America misread the politics of the Middle East just as it misread Vietnamese nationalism in the 1960s. However, it's not true that nobody in American government had drawn a lesson from that war. The first President Bush, a wiser man than his son, had taken to heart the lesson that force should be used for precise military purposes, not nation-building.
Iraq's invasion of Kuwait in 1990 was the first test of a "new world order" Bush snr had proclaimed after the collapse of the Soviet Union. The first Gulf War wrote a textbook for the use of military power, sending overwhelming force with a specific achievable objective and withdrawing once it was achieved. The second Gulf War broke all those rules.
It seems longer than 20 years since the optimism of the new world order. Just about all the 20th century's problems seemed to be resolved. The Cold War was over, Eastern Europe was free, apartheid had gone, Ulster came to agreement. Only the Arab-Israeli conflict remained.
We didn't know what was happening in Afghanistan. The closest I've been to that country is a window seat of an aircraft, high above. Down below were endless arid mountain ranges with thin green strips between them, remote populated valleys. You could imagine how hard it is to govern.
Somewhere down there in the years 1996-2001, when the Taliban were in charge, victorious mujahideen were training for bigger targets. Bin Laden was not the only one. The founders of al-Shabab, al Qaeda in the Islamic Maghreb and the group that became Isis were there too.
They and others like them have all been celebrating the return of the Taliban. They think it means they're winning.