I was standing on Brixton High Street, in South London, at 7 in the morning, looking at a row of looted shops.
A man, unshaven and in a track-suit pants trousers, walked by with a pit bull terrier on a leash. The dog paused in the middle of the street, and slowly defecated.
The man looked on, with apparent pride, until the dog had finished. Then men and dog continued their swagger across the road.
At this point, I committed a foolish error. With a look of disgust on my face, I caught the man's eye. Now he was coming towards me, pit bull straining at the leash.
I knew what was coming: The menacing language, "You [expletive], what the [expletive] are you looking at?" I walked away.
This encounter: its nuances, its predictability, are familiar to anyone who knows England.
In London, well-off people with lots of opportunities often live almost next door to poor people who live blighted, frustrated lives.
I am in the first category, and barely know the people in the second category who live in the subsidised housing at the opposite end of my street.
We lead separate, parallel lives. I not proud of that, and it is sad.
I live in a part of London where houses cost more than a million pounds.
But the people who buy those houses do not trust the state education system, and isolate themselves from their local community by choosing to send their children to expensive private schools.
These divisions are sometimes racial, but not necessarily so. (The man with the pit bull was white, in case you're wondering).
This is a time of soul-searching for Britain.
For obvious reasons, there's been a lot of talk about the police - whether they've been too timid, whether they are a racist force like in the bad old days, and so on.
That's a valid debate. But British commentators are also asking more profound questions about what's wrong in our society.
Parenting, schools, consumer culture all are coming under scrutiny. Here is a voice from the right and here's one from the left.
Finally, have a listen to this BBC Radio interview with two girls who took part in the riots. The implication of that interview is obvious.
The government must restore law and order, and hopefully sooner rather than later. But the riots are a symptom of a deep malaise in this country and that is what makes the events of the past few days so depressing.