When Vermont poet and playwright David Budbill was visiting his father in a nursing home 20 years ago, he didn’t know the notes he took there would become the groundwork for a play. Fascinated with the way his father, who had dementia, tangled the past and present, Budbill did what writers do: He jotted down snippets of dialogue.

Two decades and countless revisions later, the voices from his notebook have come to life in a new play about growing old called A Song for My Father.

“It started out as an autobiographical play,” Budbill says. “But, as always, it ends up as something else.”

Budbill refers to it as a “memory play.” Its two acts take place entirely in the mind of Randy Wolf, the character he loosely modeled on himself. Randy’s imagination jumps around in time, from conversations with his mother, Ruth, who died decades before his father, to scenes of Randy’s early childhood and college years, to a wrenching recreation of a physical fight with his father, Frank.

A Song for My Father, which opens at Lost Nation Theater in Montpelier this Thursday, is directed by Andrew Doe and performed by Vermont actors John D. Alexander, Robert Nuner, Tara Lee Downs and Ruth Wallman. While the audience files into the theater, a slideshow of photographs depicting industrial Cleveland during the 1940s and ’50s sets the scene.

Budbill, best known for his play about life in rural Vermont, Judevine, was born in Cleveland in 1940. His mother was a minister’s daughter, his father a streetcar driver who quit school in seventh grade to help support the family. Budbill, like his protagonist, Randy, was the first person in his family to graduate from high school, let alone college and grad school, and this educational and class divide plays a central role in his new play.

In one scene, when Randy tells his father he’s moving to Vermont, Frank blows up.

“He thinks the education and moving to Vermont is going to separate them, make it impossible for them to relate to each other,” Budbill says. “And in some ways it’s true.”

But it’s not as true as Frank thinks. Despite the vastly different worlds they inhabit, father and son love each other deeply. Budbill’s own dad encouraged him to get an education, he says, though he knew it would drive a cultural wedge between them.

Throughout the play, Budbill explores Frank’s loneliness as he ages and the guilt Randy feels for not being there for his father before he got sick. But he also discovers the ties that bind them. And he does it with humor, albeit black at times.

“I don’t tiptoe around the issues,” Budbill says. “The scenes between Randy and Frank in the nursing home and starting to have dementia are actually pretty funny.”

Budbill, who has performed for many years with jazz musicians, says he thinks of the play as a kind of blues.

“It does what blues does,” he says. “It confronts the way the world really is. When you’re done listening to the blues, you feel better.”

Throughout his process of putting the show together, working with actors and speaking with reporters, Budbill says, almost everyone has shared memories of their own struggles with aging parents or grandparents. The story of a son watching his father age is far from unique, but that’s just what audiences will relate to, he suggests.

“If you wait long enough, everyone has these stories,” Budbill adds.

He’s pretty sure his father, who died in 1999, would have been flattered to see the play his son wrote about him.

“You know, in the title, I left out the word ‘love,’” he says. “It is really a love song for my father.”