IT IS said that when the inscrutably Machiavellian French diplomat Charles-Maurice de Talleyrand died in 1838 after a lifetime spent saying one thing, meaning another and doing a third, his Austrian arch-rival Metternich observed: “Mmmm. I wonder what he meant by that.”

They’ve been saying much the same about Bob Dylan for most of his life, and now it’s begun again. After more than four decades of very public privacy the great man is emerging like a butterfly, albeit rather wrinkled and distinctly hoarse. The first volume of Dylan’s autobiography, Chronicles, has been published to widespread critical acclaim — not to mention considerable surprise at its lucidity and readability. Now comes No Direction Home: Bob Dylan, a remarkable documentary film by Martin Scorsese.

This is Dylan uncovered, both by himself and by the people who knew him when he arrived in New York in the winter of 1960-61 with a suitcase, a guitar and an attitude. But why now? Intimations of mortality, perhaps. It’s not dark yet, but it’s gettin’ there. Maybe he’s trying to get to Heaven before they close the door.

OK, enough already: no more allusions. Robert Zimmerman was born and brought up in Minnesota. That’s about as much as anyone knows, and Scorsese’s film sheds little more than a pencil light on it. Bob Dylan was born at the age of 20 at the Gaslight club in Greenwich Village, and five years later he revolutionised popular music. This documentary chronicles the period in between.

The fulcrum around which it revolves, and to which it continually returns, is Like a Rolling Stone — the song that Uncut magazine last month voted the single most important popular cultural influence of the past 50 years. How did Dylan get to there from singing traditional folk songs in unpaid Greenwich Village “basket clubs”, his girlfriend passing a bread basket round the audience for cash as he played? How was it that, just as Pete Seeger and Allen Ginsberg were hailing the passing of the torch of protest from Woody Guthrie to a new generation (“When I heard A Hard Rain’s Gonna Fall, I wept,” said Ginsberg), its recipient was using that torch to light a fire under them? To tell that story Scorsese uses footage of Dylan performances from the early 1960s, interspersed with interviews. There is an unusually forthcoming Dylan himself, plus a cast of characters who make it clear that he was a young man on the make. Dylan used them, then ditched them, but they look back now with rueful and affectionate amusement.

Dave van Ronk was an established artist on the New York folk circuit. The newcomer, desperate for work, talked van Ronk into allowing him a guest slot in his residency at the Gaslight. By way of thanks, Dylan appropriated van Ronk’s chord structure and phrasing for the classic House of the Rising Sun, recorded it on his first album, then bashfully asked if it was OK. “It was too late,” van Ronk says. “I couldn’t play the song after that. Everybody assumed I’d stolen it from Bobby.”

Then he grins: “But the Animals had a big hit with the same arrangement, then Bobby told me he couldn’t play it any more because everybody thought he’d stolen it from them!” Joan Baez was only a year older than Dylan, but she behaved like his mother then and still does. At the Newport Folk Festival in July 1963 she, an established star, took the apparently shy young man onstage, introduced him to the audience and watched as he took the festival by storm. Three years later, on tour with Dylan in Britain and by now his lover, she waited in vain for the favour to be returned. “Every night I waited for him to invite me onstage. It never happened,” she says. “And I realised, he’s never going to do it.”

At which point, Scorsese cleverly cuts to Dylan today: “Yeah, I felt bad about that. But you can’t be wise and in love at the same time. I hope she’ll see the light about that some time.”

Watching the young Dylan perform in the 1960s it’s difficult not to feel a pang of nostalgia for that long-gone vocal power, the anger as he spat out those vicious lyrics decrying the injustices of the age. But that would be to fall into the same trap as the folkies who complained of betrayal outside concert halls the length of Britain in 1966. “I came to see a folk singer, not a pop group,” whinges one Aran sweater.

Then, in the background, an unidentified young female voice responds: “Yeah, but where will you ever hear a pop group like that?” Whoever she was, she was right. Predictions that Dylan has shot his bolt have studded his career, and they have always been wrong.

Scorsese’s documentary ends with the last few minutes of his notorious concert at the Manchester Free Trade Hall during that 1966 tour. The soundtrack is familiar but the film footage, previously unseen, sensational.

“Judas!” cries the voice from the audience.

Dylan moves to the front of the stage. “I don’t believe you,” he says. He moves away, then returns. “You’re a liar,” he says. Then he turns to the band and bellows: “Play it f****** loud.”

The snare drum raps once, the organ kicks in, the band fires up, Dylan turns to the microphone and howls: “Once upon a time, you dressed so fine, threw the bums a dime, in your prime . . .”

And popular music was changed, changed utterly.

• No Direction Home: Bob Dylan will be broadcast by BBC Two on Arena, Sept 26

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