Impossible as it may seem, our collective memory of the attacks of Sept. 11, 2001, is starting to fade.

Even among those who stood in horror as the towers fell 18 years ago, the events have lost much of their visceral sting, the inevitable consequence of time and a world that doesn’t let us linger on much for long.

And there is now a whole generation, some of them high school graduates now, that has been born since that terrible Tuesday. To them, 9/11 is history.

But for a relative few out there, the memories of 9/11 can never fade – circumstances just won’t allow it. Wednesday, the anniversary, is their day.

There are of course the nearly 3,000 people who died directly in the attacks, as well as their loved ones, for whom the Sept. 11 anniversary is not only a day of national mourning but also a day of personal – and very public – tragedy.

Wives and husbands, sons and daughters, mothers, fathers and friends were lost so suddenly. The stories that came out later – that are still coming out today – of final phone calls and messages, and of tremendous acts of humanity and selfless courage aboard the airplanes and in the burning buildings, should be told and remembered.

And they are, by those who can’t forget, in many places, including the plaza at the 9/11 Memorial and Museum, where every day people leave trinkets and reminders as a way to mark the lives of loved ones lost in such an incomprehensible way.

As The New York Times reported, one message said simply: “Hay gente aun que te aman” – “There are still people who love you.”

Today is for the first responders, too, who rushed to the scene, and everyone who worked for weeks in the rubble, only to get sick from exposure to harmful chemicals at the site.

Hundreds have died since of cancer and cardiovascular illness. Thousands more are expected to develop diseases as a result of their exposure at ground zero; experts predict that the death toll as a result of the aftermath will one day exceed that of the attacks themselves.

After Republicans dragged their feet for years, Congress this year finally passed a permanent reauthorization of the September 11 Victim Compensation Fund, which will provide billions of dollars for these heroes and their families through 2090. They never should have been made to worry that they’d be left hanging; now they won’t have to.

And there are of course the thousands of members of the U.S. military who have served in the wars that followed the attacks. About 14,000 American soldiers remain in Afghanistan; 16 have been killed this year.

The seemingly intractable situation in Afghanistan shows how 9/11 echoes today, even if some of the soldiers there are too young to remember it.

The echoes can be seen in the continued influence of radical Islam, and of Islamophobia. They can be seen in our debates over troop deployments, defense spending and civil liberties. Today’s students need to know the history of 9/11 to understand much of what is going on in the world now.

But today, the anniversary of the attacks, is about the people for whom Sept. 11, 2001, is far less academic, political or abstract.

For them, the anniversary is about personal loss, and on this day, they are in our thoughts.