The day began in crystalline sunlight and endlessly blue skies, but soon whipsawed into a decade of war, economic meltdown and deep political division.
Ten years after Islamic terrorists hijacked passenger jets and crashed them into the World Trade Center and the Pentagon on Sept. 11, 2001, the America that emerged from the smoke and rubble was in some ways a very different country.
First, a story: It's said that when President Richard Nixon made his groundbreaking visit to Communist China in 1972, he asked Premier Zhou Enlai what he thought about the French Revolution.
It's unclear whether Zhou thought Nixon was asking about the political upheaval of 1789 or the Paris student demonstrations just four years earlier. In any case he replied: "Too soon to tell."
It might be too soon to fully understand the impact of 9/11 as well.
Did it somehow help spark the Arab Spring because our response unleashed so much upheaval in the Middle East?
Or the tea party, which harnessed an anxiety that America had lost control of events and turned that into an intimidating political force?
It was easier to gauge the fallout on the day itself. From the moment of impact, the terrorists struck not only concrete and steel, but also the very notion of American might and invincibility.
From crowded cities to one-stoplight towns, from farmsteads to factories and across the rugged spaces where the singular character of America has been mythically chiseled and shaped, the nation held its collective breath.
Perhaps we still do.
Don't many of us pause when we hear the unmistakable scream of a jet engine in downward flight — and wait?
"I think 9/11 and its aftermath years later were a shock to our national consciousness because of the way we thought about ourselves and our place in the world," said Nicholas Burns, the American ambassador to NATO at the time and a top State Department official during the Iraq War.
"It has been a much more difficult, much more fearful time for us."
Historian Douglas Brinkley said 9/11 put America into an unfamiliar "defensive crouch." It triggered a mad rush to protect ourselves. We endorsed government measures that pierced the privacy of email and telephones, and created a mammoth security bureaucracy that frisked nuns at airports — but, two Christmases ago, missed a would-be bomber with explosives tucked into his underwear.
In the relentless search for security, we've wrestled with questions that go to the heart of who we are.
Have warrantless wiretaps made us safer or just chipped away at the wall that protects the public from overzealous authority?
Has torturing suspected terrorists saved American lives or undermined the values we trumpet around the world?
Photographs from Abu Ghraib, the infamous Baghdad prison where Americans abused and tortured Iraqis, then put them on display, shocked the world. Is that who we've become?
"I don't think America ever lost touch with the good part of itself," said former Sen. Bob Kerrey, a member of the 9/11 Commission and a congressional Medal of Honor recipient who lost part of a leg during combat in Vietnam.
CASUALTIES, CYNICISM MOUNT
Nearly 3,000 people died on Sept. 11. The wars in Afghanistan and Iraq that followed have so far claimed 6,000 American lives and tens of thousands of civilians in each country. Military suicides are at record levels. Another 45,000 U.S. troops have been wounded, some in devastating ways, and will forever bear the scars of their service.
Troops are coming home, but "there are no victory parades," Burns said.
The country is spent — emotionally and fiscally. The wars have cost us more than $1 trillion, all on credit, and that's come back to haunt us.
"Lots of kids ran down to the recruiting office," said Paul Rieckhoff, who led an infantry platoon in Iraq and now is executive director of Iraq and Afghanistan Veterans of America, a nonpartisan activist group.
"I don't think they thought they'd do five tours and come home to find an unprepared VA (Veterans Affairs Department) and unprepared work environment."
The wars took their toll in other ways as well. The invasion of Iraq became shrouded in a fog of questionable motives. The war in Afghanistan, where the 9/11 plot was hatched, turned into a sideshow.
Then just months after combat in Iraq began in 2003, then-President George W. Bush declared "mission accomplished." Yet the fighting continued for years. Casualties mounted, as did mistrust and cynicism over the entire undertaking.
How different was his quick claim of victory from what President Franklin D. Roosevelt told Americans in 1942 about the rough going yet to come in World War II?
"Your government has unmistakable confidence in your ability to hear the worst, without flinching or losing heart. ... In a democracy there is always a solemn pact of truth between government and the people."
Was there any wonder when support for the war, if not the warriors, began to slip?
"When there are wars being fought and a sense of purpose has not been clear to the public, with problems being so complex, people do lose their trust in leadership," said presidential historian Doris Kearns Goodwin.
CULTURAL DIVISION PROGRESSES
Though the dots didn't all connect, 9/11 for many became a lens for viewing everything that came after: the wars, a sagging economy, the social and cultural rancor. They provided coherence to the notion that the day was a point of demarcation.
America has long been "deeply divided on who it is and where we should go and what our priorities should be," said Richard Land, the president of the Ethics and Religious Liberty Commission of the Southern Baptist Convention. "I think 9/11 has probably sharpened it and perhaps revealed those divisions."
Resentments festered. Fringe issues became mainstream. Decorum disappeared.
"You lie!" a congressman shouted at President Barack Obama during a speech. Critics questioned the president's citizenship and warned that "death panels" in his health reform plan would decide the fate of the elderly. Lawmakers worried inexplicably that Islamic religious law, or Shariah, might gain a foothold.
"It just seems as if the post-9/11 world has been a world in which our country seems to show itself as not very good in solving problems anymore," said historian Michael Kazin of Georgetown University. "Both parties reflect this sense that America is not working very well, that we're not able to set goals and achieve them."
A brief moment of national unity did occur in the immediate aftermath of 9/11. The country became a tapestry of shared grief. Leaders spoke with one voice.
"There was this sense there would be this profound change for the better," said documentary filmmaker Ken Burns. "Americans were coming together in an unusually powerful way ... in the ashes. We live in a bittersweet memory of that collective tragedy and collective possibility. It hasn't been the same since."
Abraham Lincoln talked about the power of shared national sorrow and sacrifice at his first inaugural when he spoke of the "mystic chords of memory stretching from every battlefield and patriot grave." They bind us to our past, he seemed to be saying, and we will best weather whatever befalls us together.
Sept. 11, was that kind of common moment.
When it was over, the Earth still turned in its usual orbit and the stars in the nighttime sky burned like a billion distant campfires. But the universe had shifted somehow.
"The moment before the towers fell and the moment after feels to me absolutely like a hinge moment in world history," said playwright Tony Kushner.
Though we've felt the impact of 9/11, more will yet unfold. Ten years on, it still might be "too soon to tell."