It's been a cool, wet spring - dispiriting for Washingtonians, who expect to be in shirt sleeves by now. But, on Saturday, the sun came out and I walked over to Lincoln Park and relearned a lesson.
Lincoln Park is three blocks long and one block wide, a place of grass, trees and a couple of statues. Everyone from the neighbourhood goes there.
Washington is a place of conflict, where opposing ideas - embodied in politicians, lobbyists, journalists and academics - struggle for ascendancy. What we forget, what Lincoln Park reminds us, is that society depends on embedded assumptions of co-operation. When we lose the social interaction that both presumes and flows from those assumptions, the community suffers.
On Saturday, Lincoln Park was full of people, as it always is on weekends and on warm evenings. A young couple nestled on a blanket. Joggers huffed around its perimeter. Countless dogs fetched and frolicked. A grey-bearded guitar player recalled the Summer of Love. A young girl wobbled past on a pink bike.
I was sitting on a step when an ancient beagle-plus-other-things hobbled over. One scratch behind the ears and down he flopped, content. A quick look over to the owner, and an exchange of smiles. Unleashed dogs are strictly prohibited in Lincoln Park. Nobody cares. The neighbourhood owns this park, whatever the government might say, and the neighbourhood thinks dogs are just fine.
Most of the people who come to Lincoln Park are white, but some are black, and that's encouraging given the legacy of segregation in this town. In Washington, in 2009, it is fair to say that whites and blacks who are middle class or higher work and live together in reasonable amity, though there is still tension between the middle and lower, mostly black, classes.
There's a small restaurant, a dry cleaner and a corner store on the park's perimeter. The corner store has a pretty good selection of wines. (Anyone who tells you that state-controlled liquor stores offer greater variety and lower prices has never lived in a city free of them.)
Because this is an old neighbourhood, built on a grid, with narrow lots, those stores are an easy walk for anyone in the neighbourhood, affording another excuse to loiter in the park, milk jug under your arm, watching the children and dogs, and feeling good about your community.
After the Second World War, politicians and planners did great damage to community. They decided that no matter what the question was, the answer was the car. So they built suburbs with curved roads and wide lots. They flipped houses around so they faced inward, centred on their backyards, with garages stuck on the front, so people would live in their own space rather than share their street.
And they imposed zoning, which rendered the corner store or restaurant illegal, forcing them into malls and plazas, which you had to drive to. There were parks, but they were pretty treeless and out of the way, and people didn't go there as much, because walking around your neighbourhood was something there was no reason to do.
Many of the Gen Xers and millennials raised in these suburbs decided they would rather live anywhere but there. They have flooded back into the cities - not every city, but many of them - transforming down-and-out neighbourhoods back into the flourishing communities they were before the war.
That's why, as housing prices collapsed in the Maryland and Virginia suburbs surrounding Washington last year, and newspapers ran stories about vacant malls and desperate landlords, housing prices in D.C. held firm.
That's why so mundane a place as a neighbourhood park on a Saturday afternoon is something to celebrate. Because without community, without co-operation, nothing is worth anything.
John Ibbitson