The memory seems as clear as could possibly be -- the ball of fire from the World Trade Center, the billowing smoke from the Pentagon, the ash-strewn streets of lower Manhattan, the fatigued firemen mourning their colleagues.
And yet this week's commemorations of the first anniversary of the Sept. 11 attacks will be another step in the construction of the national memory of these events.
All of us are certain we know exactly what we saw and experienced on that day a year ago. And yet what did we see? A national tragedy? A national renewal? The beginning of a victorious struggle over terrorism? The beginning of years of endless warfare in regions far from our own soil?
"It is a mistake to suggest our memory of the past is a pure, unsullied phenomenon," says Gary Gerstle, a historian at the University of Maryland, College Park. "Memory has always been constructed. Traditions have always been invented. We are now in the process of inventing the memory of 9/11."
Some of this takes place out in the open -- arguments about the role of Islam, about what makes a hero, about the appropriate memorial in lower Manhattan. But much is too subtle to see. "An event like that is like the irritant in the clam, a grain of sand that eventually creates a pearl," says Ken Burns, the documentary producer who made The Civil War, Baseball and Jazz.
"One is never quite aware of the imperceptible layers that are added, one only knows it after the fact. ... We are in the very early stages of responding to this irritant, only beginning to create the pearl of memory. It is interesting to see the half steps, the faltering first steps on the way to doing that."
Adam Goodheart, writer-in-residence at the C.W. Starr Center at Washington College, says he can detect a shift in the initial narrative. "I think there was a sense in which the current generation was measuring itself against the World War II generation, and Sept. 11 was embraced as here, at last, our great test, our Pearl Harbor. Now that seems much less fresh. It doesn't seem as exciting or heroic any more, more of a mess. But at the time it seemed like a gauntlet thrown at us."
The broadcast of Burns' The Civil War in 1990 in some ways marked the end of a generation of America ignoring its history -- "We burned it like jet fuel," Burns says -- and instead almost obsessing about it, minutely examining first the Civil War, then World War II.
One of the most interesting of the many books to come out of that was David W. Blight's Race and Reunion. It details how the national memory of the Civil War was a long construction process that eventually eliminated the role of slavery in the South and black troops in the North to make it a fight between honorable white men.
"These are things that take place over generations," says Lonnie G. Bunch, president of the Chicago Historical Society. "Ultimately the memory of Sept. 11 will go through a variety of prisms until it becomes the national memory."
Along the way it will be pushed and pulled, massaged and mauled, used and misused.
"People assume somehow it is inevitable the way these things arise, but in fact they are the product of particular actions and interests and agendas ... that invariably shape the process of memory construction," says Robert Friedel, who has worked at the Smithsonian's National Museum of American History and now teaches at the University of Maryland.
There is a virtual memory construction industry already at work on Sept. 11. Media and museums, pundits and politicians, academics and analysts are eager to put their stamp on an event of this magnitude. Wednesday's commemorations will be part of that.
"Frankly, I think we are overdoing it," says Blight, a professor at Amherst College, of the extensive focus on the first anniversary. "It's like saying we knew everything about Pearl Harbor by December of 1942. The meaning of Sept. 11 is clear on one level ... but for its historical significance, we need a longer view. Pearl Harbor led to the largest war in human history and a transformation of the world. Will Sept. 11 lead to that? I have my doubts, but no one knows."
Gerstle says there is nothing new about various players trying to shape memory, but "this process has become more entrepreneurial. After the Civil War, the process of memory was in the hands of veterans, politicians and other groups, but I certainly now feel it is the information industries, the culture industries, that are driving the current moment."
One of the many museum exhibits will take place at the National Museum of American History. Co-curator Kathleen Kendrick says it is designed to acknowledge that the memory of this event is still being formed. The exhibit, she says, tries to dispense with the normal relationship of the curator as the authority.
"In the case of Sept. 11, no one is an expert on the topic yet," she says. "Everyone will be bringing their own story into the exhibition. People are not coming to learn something. ... We acknowledge that we are all part of the event, we are all experts."
Indeed, visitors will be asked to write or record their stories to be part of a permanent archive, to do their part in constructing the national memory.