President Obama, Jimmy Carter, Michelle Obama and Bill Clinton Today was easy. (Nikki Kahn /Post)

There is, I think, a saying in the news business that anything you can see coming in advance gets way too much coverage.

This certainly seems to be the case this year. We’re in a commemorative frenzy.

If you are an anniversary of something and you do not want, at the very minimum, a Google doodle in your honor, you are out of luck. We even honored the 161st birthday of the inventor of the Petri dish. The 161st birthday of the inventor of the Petri dish! I love Petri dishes as much as the next Petri, but – there comes a point when we have to pause in our mania for commemoration and say, “Do we really need to celebrate this one?”

The March on Washington is a case where we do.

Fifty years ago, we were given the immeasurable gift of words, fit to carry a tremendous idea. America has been fortunate in these pairings of ideas and words, from the first “We hold these truths to be self-evident” of Jefferson to Lincoln’s Gettysburg address to King’s speech on the Lincoln Memorial steps, as President Obama reminded us this rainy and unremarkable Wednesday. Sure, Obama gave an eloquent and powerful speech. But if you go to a birthday celebration expecting a birth, you’re bound to be disappointed.

It was fitting and proper to do this. Remembering is an act, and it demands time. On a day when nothing else is happening, you cut a window in the present to look backwards.

But today was just a rainy Wednesday on the mall. Fifty years ago, something happened. Words happened.

Today we knew what happened that day in 1963. We could see it coming miles away and we knew what we were celebrating.

But usually the moments that you celebrate 50 years down the road don’t come cloaked in all the trappings of a march to the capital. They spring up on you – the day a woman refuses to give up her seat. The moment that cuts through the noise when you decide that enough is enough, when you stumble upon words that light a new path. If only you could schedule these moments years in advance and get reasonable plane tickets and good seats.

It is easy to know that something is a classic 50 years after it’s published. It is easy to know that the Gettysburg Address is powerful when you first read it engraved in marble. But this is not how things happen. At first the new music sounds wrong, the new words are frightening.

King’s famous speech was itself a deviation from the script. We all agree that the March on Washington was a seminal moment — now. But the trick isn’t frowning at your grandparents’ injustices. It’s trying to figure out which of yours that your grandchildren are going to frown at. That’s far harder to spot in advance.