Have you ever seen the photo from 1976 of a white high school student who appears to be using a flag pole with an American flag on it to attack a black man in a suit? This was the searing incident for our city that came to symbolize Boston's racial troubles.

A book has just been published that thoughtfully examines how this photo was taken, what the principal participants thought then and now, and how an illustration can be a kind of archetype symbol of a whole set of events in history. The book is titled "The Soiling of Old Glory: the Story of the Photograph that Shocked America" and it is by Louis P. Masur, a professor from Trinity College in Hartford. "The Soiling of Old Glory" was the title put on this photo that won a Pulitzer Prize for then-Boston Herald photographer Stanley Forman. Forman since has become a news cameraman for WCVB Channel 5 TV.

If you lived here during those years, the events then have shaped much of how you feel about race and class issues. If you didn't live here then, you still have been impacted by how those times still affect the Boston Public Schools today and the attitudes of other residents who live around you.

On April 5, 1976, white high school students at South Boston and Charlestown High School were staging one of their periodic protests against the federal desegregation court order by walking out of school and going on a protest march. This time they went to City Hall and after they were received there by anti-busing City Councillor Louise Day Hicks, they headed out of City Hall to the corridor that runs to Washington Street.

Around the corner and inadvertently into the middle of the demonstrators came Ted Landsmark, a black man dressed in a suit who was on his way to a meeting at City Hall. Some of the demonstrators beat and kicked him. One demonstrator wielding the flag took a swipe at him. Jimmy Kelly, an ardent anti-busing leader and later a city councillor, was part of the demonstration, but tried to get Landsmark away from the students to end the fight.

Forman was a resourceful news photographer and he had the luck to be in the right place at the right time, as most great photographers do,to record this incident. Forman's photo appeared on the front page of the Boston Herald next to a story headlined, "Youths beat black lawyer at City Hall." The next day, the photo ran in newspapers around the country. It cemented an image of Boston as a city of racial divisions that could disintegrate into hatred.

Landsmark held a press conference two days after the incident with his face heavily bandaged from the broken nose and cuts he had suffered. At the press conference, he said, "that he was struck in the face with an American flag in front of City Hall not far from Faneuil Hall (which was called the Cradle of Liberty as a site of events of the American Revolution), at a location not far from the site 'where Crispus Attucks [an African-American killed in the Boston Massacre incident that led up to the American Revolution] got his.'" He went on to say "racism is the apparent direct cause of Monday's unprovoked attack on me... Safety is not the issue. Busing is not the issue. The issue involves the participation of citizens of color in all levels of government."

Perhaps even more remarkable was what this man who was the victim of this terrible racial incident then said about the question of class. "The chances of any of the kids who attacked me ending up on a major corporate board are as slim as any black kid ending up on a board," he said.

At a recent forum on the book, I asked Ted Landsmark how he --the victim of a terrible racial incident-- could speak at the same time about the role of class. Landsmark said, "I grew up in an East Harlem housing project with a single-parent mother in a neighborhood that was in the process of changing from Italian to Latino. We were all working class people living together. I knew that."

"It was easy for me to later work for Mayor Ray Flynn [who opposed busing, but was a progressive populist on economic issues] from South Boston because his dad was a longshoreman and mine was a subway conductor. I was fortunate to get to go to a year of prep school, to Yale, and to Yale Law School. I had extraordinary luck. But there for the grace of God, the lives of the kids who beat me could have been mine. "I couldn't hate those kids. I knew them [their kind of life]. I could have been them, they could have been me."

The story of the "flag kid" named Joseph Rakes, who lunged at Ted Landsmark, was a poignant one too. He was angered by busing. He said, "You can't have half your friends...they took half the boys and girls I grew up with and said, 'You're going to school on the other side of town.'"

Like me, Landsmark recognizes that many young people in Boston regard these events as distant history. "You might as well be talking to them about Lincoln freeing the slaves as talk to them about busing and how it tore neighborhoods apart," he says.

We are a very different city today than in 1976. Where people of color once feared to walk, they now may live in significant numbers. Our school system is no longer 60 percent white, but is now 85 percent kids of color. City elections cannot be won solely by getting votes from working class white neighborhoods as was true back then. Diversity and multiculturalism are values held up across many aspects of life now. Yet, if and when an issue seems to divide us, let's learn from our past and work very hard to find the common ground.

Lewis Finfer is a Dorchester resident and director of the Dorchester-based Massachusetts Communities Action Network.