Longtime Los Angeles Times critic Robert Hilburn just authored the definitive Paul Simon biography even though he didn't talk to either Art Garfunkel, Simon's famous musical partner, or Edie Brickell, Simon's third and current wife.

"Paul Simon: The Life" is based on 100 hours of conversations with the notoriously private Simon plus interviews with more than 100 people in his life, from childhood pals to musical associates to two ex-wives. Simon cooperated but he didn't have control over the content.

Hilburn estimates about 80 percent of the book is original research. His goal was to write as much about the songwriting process as about Simon's personal life.

In an interview, Hilburn shared some of his reflections.

On not interviewing Garfunkel

Garfunkel declined to get involved because he was working on his own memoir, which was published in the fall of 2017. Still, the writer pursued Garfunkel for another year and a half. "He didn't want to do anything to help Paul; they're still so far apart," said Hilburn. "I told him 'It's my book, not Paul's.' "

On getting the private Simon to open up

"Initially, all he wanted to talk about was his new album. ... I missed my deadline and he saw how disappointed I was about that. Then he started opening up because the last 20 hours of the 100 we talked were better than the first 80."

On off-limit topics

Simon gave Hilburn a list of friends from his days in London but said Kathy Chitty, his first girlfriend and muse, was out of bounds. So Hilburn e-mailed back: "Nobody can be off limits. I'll find her myself." A minute later, Simon responds: "I understand."

Singer-songwriter Brickell, Simon's wife of 26 years with whom he has three children, refused to talk. She's equally private. Simon would not discuss the domestic dispute that landed him and Brickell in court in 2014 but when the author asked for a recent photo of the couple, the singer e-mailed an offer of a 2016 photo of them renewing their vows, an event he'd never mentioned to Hilburn.

On 10 adjectives to describe Paul Simon

"Smart. Private. Funny. He has a wry sense of humor. Thoughtful. Sensitive. Empathetic. Warm. Considerate. Reserved. Caring. When he stole home in a high school baseball game, he worried as soon as he crossed the plate on how bad the pitcher must feel."

On the importance of Simon & Garfunkel's Minneapolis-reared manager Mort Lewis

When they met in 1965, Simon tested Lewis, who had worked with jazz star Dave Brubeck and the vocal group Brothers Four. He asked how much S&G would be making in six months. Lewis said $10,000 a week. If they didn't, Simon wanted out of the management deal. When they ended up making $10,500 the first weekend, Simon was stunned. He thought Lewis was B.S.'ing.

"Mort was his father in the music business," Hilburn observed. "Paul trusted him implicitly." So much so that after Simon & Garfunkel's Central Park reunion concert in 1981, he gave Lewis a check for $100,000. "What's that for? All I did was refer a phone call," Lewis said. Simon said, "Mort, you'll always be Simon & Garfunkel's manager."

On Simon's friendship with St. Louis Park-reared New York Times columnist Thomas Friedman

"Paul's very intellectual. They don't talk about music. They talk about things in life, politics, whatever interests them. They have lunch and go to Yankees games."

On Simon's relationship with Bob Dylan

Their relationship was "testy" at first because Simon, a huge Dylan admirer, thought the Minnesotan was laughing at him during an early Greenwich Village performance. They soon became rivals of sorts on the same record label.

"Over time, that went away," Hilburn explained. "They have a nice, respectful relationship."