Woodstock, a baby boomer's symbol for peace and love, is a Gen-Xer's symbol for commercialism, hip-hop and, as of Sunday, violence.

Rabbi Yosef Langer, head of Chabad of S.F., sees the event as belonging to both generations.

Traveling with a Chabad crew and a few mitzvah-making tools, Langer hung out backstage last weekend for the big show that attracted 225,000 music fans.

During the event where tickets sold for $150 and Coke for $4 a bottle, Langer's mission was to deliver free food and spirituality.

The rabbi also witnessed the concept of peace go up in flames as a splinter mob used the "peace candles" handed out for the closing performance to light bonfires and torch a Mercedes-Benz parked at the back of the audience.

To fuel the fires, crowds tore off wooden planks from fences that were painted with murals over the weekend. The blaze spread under sound trucks, which exploded to a cheering mob. Riled concertgoers also smashed tents, raided merchandise and busted ATM machines.

Langer felt he could nothing but watch, afraid the mayhem might spread backstage and engulf his rented RV.

"It was unfortunate. What people are going to remember is the fire and pandemonium," he said the day after the concert ended. "But you can't blame all the kids who were at Woodstock."

It was Langer's second Woodstock. The rabbi, known in rock circles for his friendship with the late concert promoter Bill Graham and with rock star Perry Farrell, didn't make the original legendary show. But Langer did catch the first revival five years ago, where the self-described "chief rabbi of Woodstock" blew the shofar on stage.

With a long, shaggy beard, Langer fits comfortably in both the Chassidic and hippie camps. In his younger years, when he was a seeker, Langer went to hear Jimi Hendrix and Janis Joplin in San Francisco. Discussing drug use in those days, Langer joked, "I smoked a lot of pot and didn't inhale. My mom said it was bad for me."

These days, Langer doesn't listen to much rock music; he prefers the Jewish spiritual music of the late Rabbi Shlomo Carlebach.

At this past Woodstock, Langer spent most of his time mingling with the audience and bands. He brought challah, wine, schnitzel and nearly a dozen layer cakes to give away.

"One person we met said we were the only ones here giving away anything free. He said we were the only ones who provided any sense of the…original concept of Woodstock."

At the concert, Langer met and prayed with hip-hop stars like Wyclef Jean and old-timers like Willie Nelson.

Apparently Jean, a former member of the Fugees, heard of Langer's spiritual charity and went to visit the rabbi.

"We made a l'chaim, on white lightning [vodka], then started talking about HaShem and the world," Langer said, using one of the names for God.

Half of Jean's crew, plus his burly bodyguard, his wife and kids, crammed into Langer's RV to sing and carouse.

Just before the performer left, the rabbi asked for a blessing from Jean. "He put his head down, meditated for a minute, and gave me a beautiful, soulful blessing," Langer said.

Such spiritual sharing, Langer added, is what Woodstock is all about.

"The original aspiration of the hippies was peace in the world. Unfortunately we didn't have the tools to get there…We didn't have the anchors to tie it down and really elevate the world," Langer said.

"Now we do have the tools. We're close to the point where all the nations will have peace. The rebbe said the way to expedite peace is to go beyond the self and touch other people."

The fiery climax of this year's Woodstock would seem to disprove Langer's belief that the lessons of the 1960s have been followed. But he sees the world's problems as misguided manifestations of hope.

"Even though maybe five people out of 200,000 really had the spirit of the '60s, we're still trying to make this world a better place," he said. "That doesn't discourage me from putting out that message."