WASHINGTON

I was walking through a deserted downtown on Christmas Eve with a friend, past the lonely, gray Treasury Building, past the snowy White House with no president inside.

“I hope the terrorists don’t think this is a good time to attack,” I said, looking protectively at the White House, which always looks smaller and more vulnerable and beautiful than you expect, no matter how often you see it up close.

I thought our guard might be down because of the holiday; now I realize our guard is down every day.

One thrilling thing about moving from W. to Barack Obama was that Obama seemed like an avatar of modernity.