Any adult American alive in the fall of 2001 can recount what they were doing that September morning when al-Qaida hijackers attacked the United States.
The day before the tenth anniversary of September 11, the country's past two presidents and the current one shared their reflections of that fateful day. As the nation takes Sunday to reflect upon the meaning of the attacks in their personal lives, these three leaders reflected on what the attacks meant to the nation.
Former President George Bush and former President Bill Clinton were both in Shanksville, Pennsylvania on Saturday, to commemorate the 40 passengers and crew aboard United Airlines Flight 93 that died after charging the terrorists in the plane's cockpit.
President Bush told the assembled crowd, many family of those who died on the flight, "With the distance of a decade, 9/11 can feel like part of a different era. But for the families of those men and women stolen, that day will never feel like history."
He said the thousands that went to work at the Pentagon, in the World Trade Center, and who boarded those ill-fated flights had done nothing to provoke the al-Qaida terrorists. "One of the lessons of 9/11 is that evil is real, and so is courage."
President Bush recalled the image of a unified country ten years ago that stands in contrast to today's divided society. "In the days after 9/11, the response came like a single hand over a single heart," the president said. "Members of Congress from both sides of the aisle gathered on the steps of the Capitol and sang God Bless America."
Bush called for a return to that sense of unity, "Americans have never been defined by our disagreements. Whatever challenges we face today or in the future, we must never lose faith in our ability to meet them together."
The former president said one of 9/11's lessons was that the United States could not afford to withdraw from its leadership role in the world. "It may be tempting to think it doesn't matter what happens to a villager in Afghanistan or a child in Africa," Bush said, "but the temptation of isolation is deadly wrong."
President Clinton, speaking at the same event, touched on the acts of heroism that emerged from the September 11 attacks as an inspiration to the country.
He compared passengers aboard Flight 93 to the heroes of the Alamo, or the Greeks that fought at the battle of Thermopylae, when 300 Spartan warriors all died defending their country from an overwhelming foe.
"There has always been a special place in the common memory for those who deliberately, knowingly, certainly laid down their lives for other other people to live on," Clinton said.
The former president told the assembled crowd that what set the heroism of the Flight 93 passengers apart from the Alamo and Thermopylae was the fact that they gave their lives for the country not as soldiers, but as citizens.
"With almost no time to decide, they gave the whole country an incalculable gift," Clinton said. "They saved the Capitol from attack, they saved God knows how many lives, they saved the terrorists from claiming the symbolic victory of smashing the center of American government, and they did it as citizens."
Closer to home, President Obama first visited Arlington Cemetery with first lady Michelle Obama before going to the food charity D.C. Central Kitchen on Saturday. There, he made the September 11 anniversary a call to service.
The president said that public service programs like the one run at D.C. Central Kitchen "are part of what the spirit of remembering 9/11's all about - the country being unified and looking out for one another.''
In an email sent to supporters, the president said service was a way for the average citizen to pay tribute to those who lost their lives ten years ago. ``With just a small act of service, or a simple act of kindness towards others," he wrote, "you can both honor those we lost and those who serve us still, and help us recapture the spirit of generosity and compassion that followed 9/11."