I could analyze the inaugural events for signs of how time has passed and how things have changed.
But the moment that struck and stays with me is simple and devoid of political import:
I'm shivering with the crowd on the National Mall, peering at the jumbo screen. We've dutifully applauded the procession of politicians and dignitaries.
Then Malia and Sasha appear, click-clacking down the Capitol stairs, eyes on their feet so they don't trip. Cheers rise and I hear scattered calls:
"The girls!" from the elderly women next to me. "The girls!" from the flag-waving troupe of pre-teens aiming cellphones at the jumbo screen.
The girls. It's what I've always called my daughters — and still do, though the youngest of the three is now 22. It's a phrase that freezes them in place, binds sisters into a unit.
The Obama daughters are clearly outgrowing the shorthand.
Sasha is no longer the little kid who clings to Daddy when she's tired; she's a wisecracking 11-year-old with a budding sense of style. And Malia has finessed the awkward passage into adolescence, fashion-model pretty at 14, with her mother's presence and her father's smile.
We're watching them grow up in the White House; and for all the trappings of privilege, they seem so ordinary, so natural, so unimpressed with it all.
The girls found the week's festivities, at times, as boring as I did. They diddled with their cellphones, made faces into their cameras. Malia texted. Sasha yawned.
They could have been my daughters, or yours. We've embraced them as ours. They connect us to this president in a way that can't be measured by politics or experienced at a ball.
The learning curve of a president is not much different, in some ways, from the learning curve of a father. Teenagers can be as intractable as John Boehner or Mitch McConnell.
Obama lamented to reporters this month that his daughters aren't so keen anymore about having him around. I felt a twinge of sympathy; there are limits to his power.