– Ken Burns has checked into one of Minnesota's most famous institutions plenty of times as a patient, but Wednesday he was strictly in the delivery business, offering a sneak preview of his upcoming documentary, "The Mayo Clinic: Faith, Hope, Science."

The two-hour film won't debut on PBS until Sept. 25, but roughly 500 Mayo staffers, selected by lottery, got to see more than 10 minutes of footage with live commentary from Burns, the Emmy-winning auteur behind "The Civil War," "Jazz" and "Baseball."

Burns, who gets his annual checkup at Mayo, said the history of the internationally respected hospital was right in his wheelhouse.

"This is the quintessential American story," said Burns, who got a standing ovation after Mayo's version of an afternoon at the movies. "The principle at work here was both males and females working together with Midwestern ethos. That's something special here."

Judging from the selected clips, the project resembles a lot of the filmmaker's past work, with lots of black-and-white photos of the Sisters of St. Francis developing their nursing skills in the early 1900s, and Burns mainstay Peter Coyote as narrator.

But there is also contemporary footage, including a segment showing Minnesota Orchestra associate concertmaster Roger Frisch fiddling on his violin during brain surgery so doctors could gauge the correct placement of electrodes aimed at eliminating a career-threatening tremor in his right hand.

"I must have seen that 50 times and it still moves me to my core," Burns said after the lights went up.

Many of the clips paid tribute to the Franciscan nuns — past and present — who have gone the extra mile to treat Mayo patients, starting with a 1883 tornado that was critical to the clinic's origins.

Burns, who started shooting the project two years ago, said he and his team reworked their shooting schedule in 2016 so they could film events memorializing the death of Sister Generose Gervais, longtime administrator of Saint Mary's Hospital in Rochester.

"Let's be honest: We can't compete with the sisters," nurse Kate Welp said in one warmly received clip.

These kind of inspirational moments were just what clinic trustees hoped for when they approved the project, said Dr. John Noseworthy, Mayo's president and chief executive.

"We made the decision knowing we would have no control and wondering, 'What if he produced an analytical film about science?' " said Noseworthy, who plans to retire at year's end. "But we looked back at his past films and had complete faith in his creative genius."

Burns didn't actually direct the film — those honors go to brothers Chris and Erik Ewers — but as executive producer, he played a major role in conducting interviews and culling the nearly 80 hours of footage. He is also the documentary world's most eloquent salesman, a title he more than lived up to in his Q&A with Noseworthy, quoting Ernest Hemingway, Shelby Foote and the Dalai Lama.

"One plus one will always equal two," said Burns, dressed in his trademark combo of blazer and blue jeans. "But when you add faith, relationships and art, one plus one equals three. That's in all my films."

The documentary will premiere at a time when the Mayo Clinic is leading Minnesota's largest-ever economic development project. The $5.6 billion Destination Medical Center plan, launched in 2013, blends private investment with public dollars to dramatically grow the city of Rochester over two decades, including an expansion of Mayo aimed at reinforcing its global brand. At the same time, the clinic is trimming jobs on its Albert Lea campus.

But for the most part, Burns steers clear of news headlines from the past 25 years, a strategy he'll apply in his next blockbuster: a 2019 miniseries on country music, which will pretty much skip over tunes recorded since the mid-1990s.

"I'm not a journalist," he said. "I'm in the history business. None of us intended to make a valentine or give the Mayo a wet kiss. But this is an overwhelmingly positive story."

Michael Kehoe, one of the staffers lucky enough to win a seat in the auditorium, came away impressed.

"They did a real nice job of capturing the essence," said Kehoe, who works in the company's IT department. "They got the secret sauce."

So what's his favorite film from Burns' rich catalog?

"I have a new one," he said.