President Obama transformed the Florida shooting that has become a national protest movement with a single sentence: "If I had a son, he'd look like Trayvon." Once again, the president transcended race while addressing it.

Obama spoke as a father - any father. And yet there was no one who read or heard his words who didn't understand that he was also speaking as a black father who could have had a black son resembling Trayvon Martin, the teenager whose shooting death has inflamed black America while reminding white America that the legacy of racial injustice is long, complicated, and always painful.

I am a white father who has a story about his black son - that is, a boy who grew up with my son, as close as two friends can be.

They met in first grade at Meredith School, a public elementary school at Fifth and Fitzwater Streets, in a South Philadelphia neighborhood that people were still getting used to calling "Queen Village." It was the early '70s, and young white families who were buying rowhouses in such neighborhoods, as my family did, were referred to in real estate sections as "urban pioneers" rather than gentrifiers.

We were innocents of a sort in the Philadelphia public school system. Still in our twenties, we initially expected our kids to get the same education we had in the suburbs. Meredith at the time was 80 percent black, with many of its students coming from the high-rise public housing projects five blocks away, where parents fudged their addresses so their children could go to Meredith. We sent our children to Meredith because we liked and believed in it, and we continued to believe in it through grade school. Today, Meredith is one of the success stories of neighborhood public schools in Philadelphia, but back in the day, it wasn't so easy.

Best friends

My son Danny was bullied by a kid from the neighborhood, a mean white kid whom I remember as half my son's size, and yet who terrorized him to the extent that Danny retreated inside at any hint of his presence.

And then came Robert. Robert was Danny's classmate, a black kid who lived in the projects down the street. How they became best friends, I do not know. Robert just showed up one day and never left.

The bullying stopped whenever Robert was around. Danny grew more confident by degrees. By fifth grade, he was unafraid. By seventh grade, he was adventurous.

By eighth grade, he was - well, as he once put it to me, black. He was joking, of course, because he would always be white in the eyes of America. And of the Philadelphia police.

'Next time'

One spring morning in 1985, while Robert was walking to school from his mother's apartment in the Southwark Plaza housing project, at Fourth and Washington, he was stopped by the police and put in the back of a wagon. He was 13 years old.

The officers drove him to Sixth and South Streets, where a woman's purse had been snatched. The woman was waiting there when the police wagon pulled up. When its back doors opened, a bewildered boy in tears emerged.

The woman was furious. "I told you it was a man who did this, 6 feet tall. You've brought me a boy. Don't you know the difference?"

The police officers shrugged, put Robert back in the wagon, and drove him back to Meredith School, where he had told them he was a student. They pulled up outside the front doors on Fifth Street about half an hour after classes had begun. Robert was still sobbing when they opened the doors and left him on the sidewalk alone.

The policemen didn't call his mother, didn't offer to walk him inside to explain why he was late, and didn't apologize for the mistake. They simply let him out and drove away after a four-word warning: "Next time, don't cry."

Those are words that no white father in Philadelphia would ever expect a policeman to say to his son. "Next time ... " - because surely there will be a next time, and boys like Robert should learn how to take it like men. And if I had actually been the father of a boy who looked like Trayvon Martin, I would have known that.

That was all 27 years ago. We moved to West Philadelphia soon afterward. Danny and Robert went to different high schools and drifted apart, though they remained friends.

Robert eventually got caught up in drugs and dropped out of high school. But he came from a strong family, and at 19, he joined the Army, got his GED, and learned a trade. When he died of leukemia at the age of 25, he had started a family and was working for a top chef at a Center City hotel. At his funeral, I heard my son cry like I had never heard him cry before.