It has been five years, come Monday, Sept. 11, since the day that defined America as much as Pearl Harbor and the assassination of President John F. Kennedy.

We simply call it 9/11.

As the United States takes stock of the No. 1 question following the tragedy of 9/11 -- are we safer now than we were five years ago? -- another question comes to mind.

Will we ever forget?

No. Never. We will never forget.

How can we?

The loss of about 3,000 lives is certainly one reason that we should never forget what happened on Sept. 11, 2001, as the World Trade Center towers tumbled, the Pentagon was attacked and if not for the brave people on the third airliner -- perhaps the White House or the Capitol were in jeopardy.

The third flight crashed into the Pennsylvanian countryside. Theories abound, but, really, we will never know, will we?

Another reason that we should not forget is the loss of innocence that once again struck the United States.

I link Pearl Harbor in 1941, the JFK assassination in 1963 and 9/11 in 2001 together as watershed events because each represents an abrupt loss of innocence in America.

When the Japanese attacked Pearl Harbor on Dec. 7, 1941, America's fine Naval fleet was a sitting duck in Hawaii.

The Japanese had had the gall to attack Americans on American soil -- American soil that was hundreds of miles away from the continental United States. President Franklin Delano Roosevelt was right to call it "a day that will live in infamy."

Then there was the assassination of Kennedy. Just a few short years prior to the assassination on Nov. 22, 1963, JFK and his young staff (young by that day's standards of public service) had survived a razor-thin victory at the ballot box over then vice president Richard M. Nixon, then had been thrust into a world hot seat with the Cuban Missile Crisis.

A nation, enthralled by Kennedy's candor, youth and energy, had dubbed the administration "Camelot."

Alas, this leader was killed far before his time.

As Kennedy was planning for the 1964 campaign, the South was a key component to his desire for a second term. In those days our public figures rode in convertibles, seemingly oblivious to the potential dangers around them. Just as our Naval fleet was a sitting duck at Pearl Harbor, Kennedy -- who couldn't even duck from the bullets because of a restrictive back brace he was wearing -- was also a sitting duck in Dallas.

There have been other assassinations and tragedies since that day on Dealey Plaza involving world leaders, but that day in Dallas truly ripped away our innocence as much as an armed conflict could.

Who can forget John-John's crisp salute to his departed Dad?

And that brings us to 9/11.

For the years leading up to 9/11, the world had been changing. Rather than large, well-financed and well-armed nations dueling in combat over land or resources, the wars had become much smaller in scope, the motives much hazier in nature.

We saw the bombings in Europe -- market squares shattered, bloody testaments to a new kind of conflict. We even saw half of a federal courthouse blown away in Oklahoma in our heartland. That domestic terrorism made us stand up and take notice, but still, we didn't see a 9/11 in our future.

The scope, the methods, the unbelievable carnage. These were people on their way to work in New York City and Washington, D.C. They hadn't attacked anyone. They certainly did not deserve to die the way that they did -- suddenly, horribly and televised.

The image that sticks with me is that of what we first thought were pieces of the Twin Towers falling. It turned out later those falling "objects" were flesh and blood people plummeting to their deaths.

Sixteen blocks of the city they call The Big Apple will never be the same.

The 9/11 tragedy fuels political debate. It fuels issues of military policy. It fuels debates over what constitutes privacy for individuals.

And five years later, the chills still run down the collective spine of a nation that, once again, lost its innocence.

Mason is the editor of The Marshall Democrat-News. Spectrum appears on Friday.