When he launched his campaign for mayor in 2013, Marty Walsh assumed he had a working grasp of the city’s major issues. Not only was he Boston born and bred, he had been a state legislator for 16 years.

He discovered that he had perhaps taken a bit for granted.

At a campaign event in Jamaica Plain, a retired school administrator named Patricia Kelly asked a question that got under his skin: “What are you going to do about racism in Boston?’’

By his own admission, Walsh responded defensively and superficially. He said he had represented a diverse legislative district and founded a program to bring people of color into the building trades. But that didn’t mean he was prepared to say what he would do as mayor about race.

He wasn’t.

“I realized I was just learning, that it was my first day of learning about it,’’ Walsh said this week. “Even though I’d spent 16 years as an elected official, I was just learning about it that night. I knew about it and knew there was racism in Boston — and as a white, Irish-Catholic politician, it’s a difficult thing to talk about. It doesn’t roll off your tongue like other things do.’’

On Saturday, Walsh will kick off a citywide dialogue on race at the Cutler Majestic Theater. Going where few white politicians dare, he believes the city needs to have an open discussion. The event is planned as the first of several across the city.

Walsh doesn’t really know what the conversation will or can accomplish. But he is convinced that it is a discussion that a changing city needs to embrace.

“What would I like? Obviously I’d like a harmonious, peaceful, understanding community of everybody,’’ Walsh said. “But, in saying that, these dialogues are going to bring up hard feelings. They’re also going to educate people.’’

The idea of convening a conversation on race has been percolating for a long time. Walsh has held two closed-door meetings with diverse community groups to discuss the issue and sought input from community leaders and people of color on his staff.

On the other hand, the turmoil over racial incidents at Boston Latin School illustrated just how potent and sensitive racial issues remain. Walsh’s awkward handling of it didn’t win universal acclaim, either. Both he, and the city, have plenty of work to do in learning how to address racially sensitive matters.

Such is the longstanding reluctance to try to talk candidly about race that I asked Walsh why he had decided to make the attempt. If Boston politics has a third-rail issue, surely this is it.

“Sometimes it’s good to deal with the third rail,’’ Walsh said. “I’m the mayor of Boston; I’m the mayor of everyone. I think it’s important to have this dialogue. This date was set long before the presidential election, but I think it’s even more important now to have the dialogue. In a lot of ways, it’s a divided country, and you don’t pull together unless you have dialogue.’’

Kelly, Walsh’s campaign interlocutor, is a veteran of Boston’s racial divides. An African-American teacher, she began her career at an elementary school in Charlestown in 1974, the first year of court-ordered desegregation. She went on to become a principal and assistant superintendent before retiring five years ago. She and her husband now conduct cultural competency training, mostly for educators.

Walsh invited her to City Hall last year to thank her for prodding him to think more seriously about the city’s racial issues. Kelly says she welcomes the new series of conversations but hopes Walsh’s efforts don’t end there. She’s especially interested, she says, in seeing how the city addresses the ongoing racial issues at Boston Latin.

“It’s always great to have dialogues,’’ she said. “But at some point you need to take action.’’

She’s right. But pushing people to see what they’ve overlooked can be an important step, too.

Adrian Walker is a Globe columnist. He can be reached at adrian.walker @globe.com. Follow him on Twitter @Adrian_Walker.