Eight-time Tony award-winning composer Stephen Sondheim regaled a Santa Rosa crowd Saturday with memories of a plummy voiced Hermione Gingold and an enigmatic Glynis Johns.

The white-haired and effortless Sondheim appeared onstage at the Santa Rosa Wells Fargo Center for the Arts in a rare, unscripted interview with Peabody Award-winning filmmaker Peter Stein. The event, billed as “A Life in the Theater,” was one in a series of presentation by Copperfield’s Books.

Sondheim, 79, has collaborated on more than a dozen landmark musicals and is largely credited with bringing musical theater to the contemporary stage. In addition to writing lyrics for such American classics as “West Side Story” and “Gypsy”, Sondheim has achieved remarkable success as a composer for groundbreaking works such as “Company,” “Follies,” “Sweeney Todd,” “Into the Woods” and “Sunday in the Park with George”.

He has been honored with myriad awards, including the Pulitzer Prize, two Grammys, an Oscar and eight Tonys, including a special award for Lifetime Achievement in the Theater in 2008.

According to Sondheim, Saturday’s interview marked his the first time he has ever traveled to California north of San Francisco. Though his fictional Meisner brothers of the musical “Wise Guys” — later called “Bounce” and then “Road Show” — hail from Benicia, Sondheim admitted Saturday to a captivated crowd, “I don’t even know where Benicia is.”

Easy and confident, Sondheim slid back in his chair as he recalled memories of actresses Glynis Johns and Hermione Gingold; and of his mentor Oscar Hammerstein, who took him under his wing and taught him his mysterious craft.

“I wanted to become what he was,” Sondheim said of the legendary theater impresario, joking, “If he had been a geologist, that’s probably what I would have been.”

Saturday, Sondheim recalled his baptism into the craft.

He was 15 years old, and he presented his mentor with an original musical about his classmates and his school.

 “It’s the worst thing I’ve ever read,” Sondheim proudly recalled Hammerstein telling him.

“He treated me like an adult,” Sondheim said. “I learned more in that afternoon than most songwriters learn in a lifetime.”

Hammerstein instructed his protégé to begin again, this time with a musical based on a play he admired. From there, Sondheim was to graduate to a play he considered flawed. Only after adapting a non-theatrical story for the stage — coincidentally, Sondheim chose “Mary Poppins”, later adapted by Disney — could the young man even attempt to write his own story.

“Once you’ve done those four musicals, then you’ll know something about writing,” Hammerstein reportedly told him.

Sondheim followed the master’s advice and in the meantime watched him at work. His freshman year of college, Sondheim worked as a gopher on the Rodgers and Hammerstein musical “Allegro” — Hammerstein’s first foray into experimental theater and la critical and commercial failure.

It was also the show that changed Sondheim’s career.

“That was the show that really affected my life and that’s because it was so experimental,” Sondheim said. “I learned to both love and be afraid of and understand what experimental musicals were all about.”

He admits he has spent much of his career trying to fix the second half of “Allegro,” and it has inadvertently changed the face of musical theater.

“In order to keep yourself alive, you have to try things that really scare you,” Sondheim said, sliding back into his chair. “That’s what’s so great about the theater,” Sondheim added. “It’s alive for, God’s sakes.”