Ripples of unrest were spreading through the pro-Bernie Sanders crowd among the delegates at the first night of the Democratic National Convention when work crews suddenly dragged a keyboard and drums onto the big stage. The attendees waiting for the Vermont senator instead got a music superstar, Paul Simon.

There were murmurs that the aging rocker might play Sanders' campaign theme song - "America" - but instead he launched into a 1970 classic - a new theme for calming an already restless Philadelphia confab: "Bridge Over Troubled Water." It didn't even matter that Simon's erstwhile partner Art Garfunkel sang on the original - anything to get squabbling Democrats to lay down their burden and get behind presumptive nominee Hillary Clinton.

An hour later, Sanders sang his own tune of peace and redemption in the key of his native Brooklyn. He stuck to his radical themes, telling the DNC that "this election is about ending the grotesque level of income and wealth inequality that we currently experience - the worst it has been since 1928." He was occasionally feisty, calling for a roll-call vote where his delegates can be heard. But his main mission Monday night came down to this: "By these measures, any objective observer will conclude that - based on her ideas and her leadership - Hillary Clinton must become the next president of the United States. The choice is not even close."

Tears streamed down the face of several female supporters near the front of the hall and the crowd gave Sanders an uproarious opening ovation for several minutes. It set the tone for the Vermont senator's almost impossible mission: Calming down a frenzy that he himself created - and not just inside the convention hall.

For the last 13 months, Sanders has crisscrossed America from Portland, Maine, to Portland, Ore., riling up crowds of 20,000 or more that filled hockey rinks and urban parks and swelled into the streets. He got his biggest cheers when the lifelong independent attacked both parties as tools of Wall Street millionaires and billionaires, and always sent the room into an uproar with these words: "We need a political revolution!"

For thousands of Sanders' most die-hard supporters, who flowed like a river down South Broad Street on Monday until they crashed hard against the black metal dam of the Wells Fargo Center security zone, the revolution that their candidate thundered about is right here, right now. Sanders is still its leader but he is no longer in full control - like the sorcerer's apprentice in Disney's Fantasia, who summoned buckets of water with a magic broomstick but doesn't know how to make the floodwaters stop.

Earlier in the day at the Convention Center, the Vermont senator was even booed by some of his own delegates as he tried to tell them that voting for Clinton was the only way to keep the demagoguery of Republican Donald Trump out of the White House. Minutes later, word filtered up from the Wells Fargo Center that his delegates were causing a minor ruckus on the convention floor, booing speakers who mentioned Clinton and chanting "No TPP!" - the Asian trade pact that Sanders and his supporters loathe - while Maryland Rep. Elijah Cummings was attempting to give a speech on voting rights.

The senator sent his delegates an urgent text begging for political peace. "Our credibility as a movement will be damaged by booing, turning of backs, walking out or other similar displays," Sanders wrote his core supporters. "That's what the corporate media wants. That's what Donald Trump wants."

Few, if anyone, seemed to be listening. At the very moment that text bells were going off, arrivals coming up the escalator at the AT&T Station subway stop near the arena were greeted with an amazing spectacle - hundreds of Sanders fans, pressing hard with their bodies and their homemade signs against the black metal fence, howling like banshees and chanting, "Hell no, DNC/We won't vote for Hillary!"

Protesters told me the hacked emails of the Democratic National Committee and now-ousted chair Debbie Wasserman Schultz, which showed bias against Sanders' primary campaign, felt like a fresh poke in the eye. Others said that - regardless of what the senator was about to say in his speech - the Sanders movement has now become more than just a campaign to them, something almost spiritual.

"I hitchhiked to be here, because I couldn't afford a bus or a car or a train," said Patricia Holmes, a 52-year-old single mother of two from York, Pa. - "unemployed or underemployed for the last eight years" - who made it to Trenton, where she crashed on a friend's couch. "We're like a family." She told me she'll "vote for whoever I have to - to keep Hillary out of office, because she is the greater evil."

"I knew I had to come for a long time. . . . I'm still trying to define exactly why," said Jim Schneider, a 57-year-old window contractor from Sandwich, Mass. "I think this is the first time I've seen a well-articulated challenge to the corporate control of the government." His ambivalence about the current state of play and whom to vote for in November was reflected in the sign he carried: "Why Are We Here? Together."

I've been fascinated by Sanders' revolution for the last year, even writing an e-book about it. I wanted to understand how an activist from the early 1960s had kept going - despite so many early setbacks, when so many others had dropped out of the struggle for progressive change and given up. I wanted to see how it would end in Philly.

But he doesn't really want it to end. Nobody on The Left does. But what does that mean? I also learned in writing Sanders' bio that he'd perfected a political high-wire act, balancing his idealism with just the right dollop of pragmatism when needed. Famously, as mayor of Burlington in the 1980s, the nation's best-known socialist ordered some of his old friends from "The Movement" arrested when they tried to block a General Electric weapons plant - because the workers inside had good union jobs and had supported Sanders.

Now, 30 years later, he's at the gates of the GE plant again.

Sanders' plans for the future are drenched in pragmatism - becoming a leading liberal voice in the Senate, writing a book on taking his movement forward that will be published one week after the fall election, and recruiting people energized by his campaign to run for office in future years. Early polls suggest there's a "silent majority" of Sanders voters - not the ones who hitchhiked here or caravanned to Philly from downtown Seattle - who will vote for Hillary because they detest Trump.

But for some, Sanders' infectious idealism about an America where the people rule, and not corporations, has been channeled into vitriol against Clinton. They'd all gone to look for America. Now they're looking for something else.