There’s a passage in the movie about Woodstock where Joan Baez takes the stage and sings a haunting a capella rendition of "Joe Hill."

I dreamed I saw Joe Hill last night, alive as you and me.
Says I “But Joe, you’re ten years dead”
“I never died” said he,
“I never died” said he.
“The Copper Bosses killed you Joe, they shot you Joe” says I.
“Takes more than guns to kill a man”
Says Joe “I didn’t die”
Says Joe “I didn’t die”

She’s this tiny waif on a giant stage, standing alone beneath a spotlight, belting out this old labor anthem to 500,000 kids who had no idea who Joe Hill was. The first time I saw it, I realized the power of a song to drill its way into the brain.

I saw Joan Baez sing that same song yesterday with her acoustic guitar, and a couple guys with electric and slide guitars for backup. It wasn’t the same, as it never could be. I already knew the wonder of "Joe Hill." What I never realized, until yesterday, was the wonder of Joan Baez.

In the old days, Baez sang with this fluttering vibrato in the higher registers that gave me the willies. She started out as a lefty folksinger before I was born and never strayed. She had her moment in the ’60s — a fling with Bob Dylan, the Woodstock appearance, etc — and as far as I was concerned, she was an icon of that time whose time had passed.

Last week another ’60s icon — Bob Dylan — was on PBS for two nights in a documentary by Martin Scorcese titled "No Direction Home." Baez appeared throughout the documentary trying to help explain Dylan. She lived with the guy, loved the guy, had become absolutely fed up with the guy and was no more able to explain Dylan than anybody else was. Throughout the interviews she came across as classy, witty and a bit hardened by the events of the past 40 years. Baez almost cynical after all these years. Imagine that.

So yesterday I went to the Hardly Strictly Bluegrass Festival, a free event in San Francisco’s Golden Gate Park, with no particular agenda in mind beyond picking an interesting act from the five playing simultaneously on stages scattered throughout the park. I got there early, before the music started. I’d never heard of any of the opening acts and the only name I knew well in the early afternoon lineup was Baez, who came on at 1:15. I’d never seen her live and figured at the years had to have taken some of the edge off that voice of hers. I also figured she’d draw a huge crowd in a lefty town like San Francisco.

I wanted to see the same Joan Baez I’d seen in the Dylan documentary, and I knew that meant I’d have to be right up front. My plan: Insinuate myself into the front row one act before Baez, then hold that ground till Baez’s set was over.

The plan worked like a charm, with one unexpected bonus: After I’d tiptoed through the maze of blankets to find a foot-wide patch of grass right next to the fence separating the crowd from the stage, I looked to my left and noticed the guy sitting there looked familiar. He looked at me and we had a moment of recognition: it was Maurice, the landscape photographer whom I’d met via FOMFOK, the hiking group I hang out with now and then.

It turned out to be a good omen. Patty Griffin came on stage in a few minutes and proceeded to blow me away. She does ballads, blues, country, traditional, sings with genuine power and emotion. A woman next to me with a camera and a giant zoom lens is taking dozens of pictures; I see her aim her lens away from the stage and notice what she’s shooting: Baez is sitting on a platform by the stage, checking out Griffin’s set. She’s drinking Budweiser from a can at 12:30 in the afternoon. Helps her voice, I bet.

Griffin finishes her set to a standing ovation. About 15 minutes later, right on schedule, Baez appears on stage. She sorta threads her way through the first couple songs, not making much of an impact. "Geeze, Patty Griffin was better," I’m thinking. Well, Joan was just warming up.

I don’t remember the exact sequence, but I know things got better when she did a cover of Johnny Cash’s "Long Black Veil." Somebody in the crowd yelled "Joe Hill," and that’s when she played it. Then she said "This is a giant song by the guy who did all the giant songs." It was Dylan’s "Hard Rain." The crowd sang along, and she was hitting her stride.

Baez has to have that one a capella song that freezes the audience in its seats. This time it’s "Swing Low, Sweet Chariot." She almost hits some of those high notes of her heyday; I’m thankful that she doesn’t. It’s a riveting song, bringing mad applause from the crowd when she finishes.

She sings a heartbreaking version of Woody Guthrie’s "Deportee," a song about Mexican migrant workers killed in a plane crash on their way back to Mexico. She closes her set with "Jerusalem," the Steve Earle song that imagines (somewhat naively) that one day the children of Abraham will live together in peace. When it’s over this young woman throws a bouquet of flowers on stage, and Baez picks it up, beaming.

I’m fairly stunned when it’s over. Against all odds, to my mind, Baez has put on an amazing show.

I realize immediately that I’ve just had one of those transcendent musical experiences that will not be equaled anywhere else at the festival. It’s not even 2:30 and there’s at least four more hours of music to check out. It’s a relief to have the "Oh Yea!" moment out of the way, so I won’t have to spend the rest of the afternoon darting from stage to stage looking for it.

With no goal for the rest of the afternoon, I just wandered around from stage to stage. I happened past the Arrow Stage when Rodney Crowell was leading a sing-along version of Dylan’s "Like a Rolling Stone." Cool moment.

Also caught the set of the Knitters,’ a country band made up of former members of X, the famous L.A. punk band of the late ’70s and early ’80s. Lots of fun: fast, rowdy country. Met some people I know from the paper, one of whom looks upon Del McCoury as a bluegrass version of God incarnate. When another mentioned he hated Del McCoury, I thought sure a fight was going to break out.

The last band I saw was Los Super Seven, a conglomerate of Tex-Mex virtuosos. Their first song, sung by Joe Ely, one of my all-time favorites, was "Deportee." Not quite as soul-rending as Baez’s version, but strong nevertheless.

My only lament from Hardly Strictly Bluegras is that it’s getting too big for its own good. The area around the Banjo Stage was mobbed with people… must’ve been 5,000 of them out there. But bigger crowds will attract even bigger talent in years to come, so there’s always that to look forward to.

Pictures from Saturday here.