Tomorrow marks 20 years since the worst terrorist attack on U.S. soil. It feels like yesterday. It feels like forever.

We’re not sure how both of those feelings are true, but they are. It’s the same alchemy of memory that transmutes decades into minutes. Parents know the feeling — those moments when the years fold in on themselves and the young man or woman before you changes into the child you cared for, before now returns just as suddenly.

Scientists say memories are plastic, that they change when we think about them. That may be true. But some things are so deeply embedded the details seem close enough to touch no matter how far removed we are. For our eldest generations Pearl Harbor was one. Virtually every Baby Boomer remembers where they were when they heard John F. Kennedy had been assassinated. Generation X remembers the Challenger explosion and its eerie echo in the Columbia. All of those generations remember when the towers fell.

There is now a full generation that doesn’t, though. College students today were either too young to remember or hadn’t yet been born. They have no meaningful memories of that blue September sky or the horror that shattered it.

For those who do remember, the scars are deep. We remember the shock, the pain that followed and the righteous anger that called for revenge. We got it. Osama bin Laden is dead, hunted to a compound in Pakistan he was too scared to leave. Khalid Sheikh Mohammed, the mastermind, awaits trial.

The price was high. Only now are we not at war in Afghanistan, the place where the attackers found shelter. An entire generation has grown up in the shadow of that war. The Taliban, who gave bin Laden and his cronies shelter, are back in control there.

The power of those 20-year-old memories to shock has been blunted somewhat. They’re still tinged with grief, but the sharp edge has dulled. That happens as time passes. Life continues. And, in words that come from a funeral for one of those who died on that day, life loves on.

Those words were attributed to Bobby McIlvaine at his funeral. His girlfriend, to whom he had planned to propose and for whom he had already bought a ring, quoted them from his journal. A recent piece in The Atlantic traced those words and found they weren’t quite accurate. He had written “Life lives on,” his handwriting just off enough that the middle word looked like love if you scanned it without looking for the misplaced dot over the “i.”

Bobby’s parents and his girlfriend, now married with children of her own, were surprised by the finding. But both sounded like him. They were something he would say. There’s a temptation to believe that they read into the scrawl what they needed to read, that there was something of a message from Bobby in what they saw.

In truth, both of the quotes hold up. We can do little else than continue to live our lives. That’s what people do. The inertia of life propels us forward even when we might want to stop. Even when it feels like everything has stopped.

Love persists, too. Those we love stay with us in innumerable ways, in bits and pieces of a million different memories. When they live, the memories sustain us until we see them again. When they’re gone, we cling to those thoughts.

No one who saw the events of 20 years ago will ever be able to forget. But as the years have gone by we think about them less frequently. For most they have gone from dominating our thoughts in the immediate aftermath to becoming something we recall only when prompted. Anniversaries are an obvious occasion for that to happen.

But life has, inevitably, lived on.

We are not the same people as we were then. We are not the same country. Those events, and everything that has happened since, has changed us. But we still pause. We still mark the date. We remember.

It’s appropriate for us to do so. The victims who died that day should be remembered. Those events should not be forgotten. For most of us, the memories will always be there.

It still feels like yesterday. It still feels like a lifetime.