I ran into a friend yesterday at my son's karate class. We hadn't spoken in literally 4 years even though our daughters were best friends since birth.

It was nice to catch up. Our conversation flew back and forth between the mundane to the 9/11 anniversary today.

He reminded me that I was the one who called him up that morning to tell him about the World Trade Center being hit. He was asleep and stumbled to the television and I still remember clearly his "What the HELL is going on?" response to me.

My son was born two days earlier and came home from the hospital on 9/11. It should have been a day filled with loving memories and good cheer. But in fact, I can barely remember most of the details of that day OUTSIDE of the attacks. Memories of my son's first expressions have been lost to images of fireballs and death.

Why do we tend to remember the painful, awful memories in our lives while oftentimes forgetting the seemingly unforgettable moments of joy?

Thanks to a new study from a Boston College psychologist, the answer may finally be at hand.

Negative events tend to be remembered in greater detail than pleasurable ones because the brain could be preparing us for future occurances of those events in question. Is that why I am STILL afraid to swim at age 36? Because when I was a small child someone knocked me into a pool and I panicked? It's my brain's way of warning me so that this trauma and danger never happens again, perhaps.

So isn't that all the more reason we SHOULD be reliving the memories of the 9/11 attacks today? I am ASTOUNDED and SHOCKED at the drive many people have to forget what happened a mere 6 years ago. Too bad that it is a "painful" thing to think about. It happened. TO ALL OF US.

Even though some may be collectively trying to put that terrible day behind us, the wiring in our brains could very well prevent us from doing it.

Our minds record every action we have ever taken, and every action ever taken upon us. But there seems to be good reason why we are reminded of the not so great times a little more often than we might like.

It's a warning signal that enables us to thrive, survive, and persevere.

Maybe we should listen to it.