Rehearsal started at 7 p.m., and they were in the middle of a scene when I arrived. “Oh, welcome,” said several voices after I had taken a seat. I said that I was just there to observe.

“You’re lucky,” said Jason Ioannides, one of the two actors standing in the middle of the room, rehearsing a scene between a reverend and a man from the small mid-western town where Book of Days is set. “You’re just in time for me to take off my pants.”

He wasn’t kidding. He did take off his pants, and I was, indeed, just in time.

Generic Theater Group has been working on Book of Days for the last six weeks. It was submitted by director Matt Johnson in an eight-page proposal to the Generic board and approved to be the group’s third production this semester.

“We usually do three shows a semester,” the play’s executive producer Janet Bowler said, “with a musical and a senior show in the spring.”

The group has between 100 and 150 members, most of which have yet to be involved in one or more show. Members are accepted if they express interest in being on the group’s listserv, and those who attend at least six plays are invited to vote in the awards ceremony for the cast of each show at the end of the semester.

“There has been an amazing turnout of freshmen and transfers this year,” Bowler said. “There are so many talented people on this campus, it’s amazing.”

Book of Days, by playwright Lanford Wilson, was a risky prospect when Johnson proposed it because this is the first year Generic’s actors have had the depth and ability to take on something that is labeled an “ensemble” piece.

“It creates a universe,” Johnson said of the play, which contains seven male and five male and five female characters.

The major difficulty in producing a play where every character is given equal attention by the playwright is that no single character is the focus, and therefore no supporting characters simply move the plot along. Despite this seemingly daunting task, Johnson seems to enjoy the idea of a play chock-full of round characters.

“It’s sort of like they’re all supporting characters,” he said. “It isn’t really any one character’s story. We’re trying to create the feeling of this town for the audience.”

Johnson, a playwright himself (his original work, “The Quaking,” was given a staged reading by the Abington Theater in New York), is a careful director. He stands close to his actors when he’s instructing them, with an unchallenged focus on their concerns and the play that he has chosen to bring to life.

“I want happy, I want ecstatic … and not so orgasmic this time,” Johnson said to sophomore Mike Palin, who was working on a monologue about his insatiable lust for cheddar cheese.

“I want your words to pack a punch,” Johnson said, with particular emphasis on “punch.” Palin plays Len, who works in a cheese factory and looks toward his passion for dairy to keep him grounded.

“Okay,” Palin said somewhat in jest just before the third or fourth try, “they’ll pack a punch.”

“Don’t make fun,” Johnson said, watching as Palin started again.

The cast of Book of Days is just starting to find their connections to their characters, a week before the play opens. When an actor has a “breakthrough” in rehearsal, it is nothing to be taken lightly. Kate Guesman, a freshman who plays “Louann,” had finished a scene with Ioannides, and an immediate and wondrous sigh filled the room with the lauding nods and smiles of her peers. “That’s it, you found her,” Johnson said.

Guesman knew she had. “She has no one,” she said. And indeed, her character carries a sense of tragedy that cannot be overlooked.

“Maybe she should kill herself at the end,” Ioannides said sarcastically from his chair.

Johnson smiled, but with an earnest attitude about the integrity of the characters. “She is not going to kill herself,” he said.

Book of Days runs Thursday through Sunday in the Lisner Downstage.