FORTUNE -- I saw the great financier, big-hearted philanthropist and enthusiastic banjo player Warren Hellman twice this year. My two sightings, neither of which had anything to do with his career as the co-founder of the leading San Francisco private-equity firm Hellman & Friedman, say a lot about this towering yet kindly man.
My first glimpse of Hellman was from afar. Sherith Israel, a grand, old San Francisco synagogue, was holding a party in late March to celebrate the re-opening of its famous domed sanctuary. It widely advertised the entertainment to commemorate the event: A concert called "Hardly Strictly Shabat," featuring Hellman's bluegrass band, the Wronglers. The name of the event was a nod to the Hardly Strictly Bluegrass Festival that Hellman funded each year in Golden Gate Park. (Days ago the city re-named Speedway Meadow, where the music festival is held, Hellman Hollow.)
Hellman was active in Jewish causes in San Francisco. But his appearance at Sherith Israel was notable because this wasn't his temple. Years ago, Hellman's family helped found Temple Emmanuel, the richer, neighboring rival to Sherith Israel. Hellman joked about this, and also his late-in-life interest in the religious aspects of Judaism.
I took my then four-year-old daughter to see the concert/sabbath service. I think she enjoyed the music, and I know she enjoyed the festive nature of the event. I'm certain that there were many in the packed sanctuary who came in part to see the spectacle of Warren Hellman's band playing at a synagogue. The big showing was a financial shot in the arm to Sherith Israel, and it was just like Hellman to lend his time to a group that needed him.
In May, I walked across the street from my office in San Francisco to interview Hellman in his office. I had become intrigued in the high-octane support for competing pension-reform plans then being proposed in the city. One, led by the city's public defender, was backed by billionaire venture capitalist Michael Moritz. The other cobbled together a coalition of city unions and public officials, led by interim Mayor Ed Lee and supported by Hellman.
Hellman had spent hours cajoling the contentious parties within what is called the "San Francisco family" to reach consensus. He was trying to be helpful. He also was grateful to city agencies, such as the police and fire fighters, who had assisted his beloved music festival.
My time with Hellman that spring day was memorable. As a founder of Bay Citizen, a newfangled, non-profit approach to local journalism, he was as interested in talking about the future of the media as he was about pension reform. Surrounded by his many banjos, he wanted to know my thoughts about journalism. He was also grumpy. He told me about a horrible row he'd had with the members of his band, some of whom are professional musicians, when he found out they had rehearsed without him. Hellman was universally praised as a kind man, but I would not wanted to have been one of his band members when he learned he'd been left out. (He said he had worked things out more than satisfactorily, but I could tell he was still genuinely angry.)
Hellman didn't have to help the city. (The proposal he backed was approved by voters in the November election.) He didn't have to help Sherith Israel. He didn't even have to help Fortune Magazine. For the article I published in June, he gamely traveled to a photo studio to pose with Tom O'Connor, head of the fire fighters' union. (The photo is a classic: The pugnacious civic leader and the pugnacious union chief, sticking to their guns.) He helped because he felt he owed the city and the many other institutions and communities that had given so much to him. I also suspect that gigging in a temple, arm-twisting union heads and bureaucrats, and sitting for a photo shoot in a national magazine also struck Hellman as a helluva lot of fun. He obviously enjoyed having fun.
Just the other day I was meeting with someone who had an idea related to community journalism and is looking for potential supporters. I suggested he go see Hellman. "I hear Warren is sick," he responded. I only very recently had heard this too, though until the San Francisco Chronicle reported it the other day I had no idea how sick. I have no doubt Hellman would have at least heard this guy out had he been well.
That same day, in front of packed audience at the Commonwealth Club of Northern California, I tried to draw out Walter Isaacson about the conundrum of the legacy of Steve Jobs, I asked: Can we admire a man whose behavior was so often so bad? (Isaacson argued forcefully that Jobs's accomplishments outweighed his vices.)
In Warren Hellman we are reminded that those of outsized achievements can be mensches as well. From Wall Street to Golden Gate Park, the world has lost a special person.