Bob Dylan the Legend, knocked down a few pegs. Thank goodness.

Bob Dylan is the greatest and most important musician of the last century.

Bob Dylan is completely full of it.

These contradictory statements have become complementary in the past few years. British author Ian Bell’s Once Upon a Time is the latest biography to portray the singer as icon, iconoclast, opportunist, liar, jerk and genius. The nearly-600 page study of Dylan’s life – actually, less than half of his life; this book ends in the mid-1970s, while an upcoming second volume will take us up to the present – serves mainly as a skeptic’s guide to some of rock music’s greatest myths.

Bell is clearly a Dylan fan but not a sycophant, and he takes joy in his role as Debunker of Legends. No, Dylan wasn’t the unquestioned Voice of a Generation; his first few albums barely approached the top of the charts. No, his 1966 motorcycle accident wasn’t some sort of Icarus/James Dean moment that ended one of the greatest artistic peaks ever; he was already creatively spent and moving on. No, Dylan didn’t abandon political song-writing in the mid-’60s; have you ever even listened to “It’s Alright, Ma (I’m Only Bleeding),” man?

But the story that Bell, a winner of the Orwell Prize for political journalism, spends most of his time chipping away at is Dylan’s own creation myth. The romanticized notion of boy genius from the heartland who moves to New York City, sings at the bedside of his in-hospice-care idol, Woody Guthrie, and claims his hero’s title of America’s most important folk singer – well, “There’s some truth in that,” as Bell writes. Variations on that phrase appear repeatedly.

Sometimes, Bell comes off as simply a contrarian, almost gleefully puncturing the ideal of righteous folkie savior. But then Bell zags where others zig, downplaying the plagiarism charges that have lately dogged Dylan. Bell succeeds in proving himself to be a steward of the truth, acting as if he’s almost forced into this role since Dylan has spent his entire life distorting the very notion of truth.

Dylan’s childhood in Hibbing, Minn. – when he was just Robert Zimmerman – takes up the lengthy first portion of the book. For all the many tales Dylan has told of his youth, we see a pretty standard upbringing. Except for one thing: Not many kids in Hibbing were bar mitzvahed. Or went to Jewish summer camp. Or had a father who was president of the local B’nai Brith.

Was Dylan’s eventual name change just one of many cases of a Jewish entertainer adopting a more fame-friendly image? Why did every story he told about his childhood gloss over his religion? Bell probes not so much to reach a conclusion but to invalidate the pat answers.

As for Dylan’s arrival in New York in the early ’60s, Bell provides an almost weekly diary. He was a “pest” and a “poseur” before he was a poet. He was a social climber and not all that cultured. His girlfriend Suze Rotolo (the girl hanging on Dylan’s arm on the cover of “The Freewheelin’ Bob Dylan”) is credited with introducing him to many of the influences – including the symbolist poet Arthur Rimbaud – that helped him fashion his definitive style. Rotolo’s 2008 memoir – one of dozens in an extensive bibliography – serves as a trusted source for Bell’s work.

Not a trusted source? That would be Dylan’s own book, Chronicles (2004), which Bell calls “a stratagem disguised as an autobiography.” The defining characteristic of Bell’s style is to circle his prey – say, D.A. Pennebaker’s 1967 film, Dont Look Back — and then peck away at the facade. Suddenly, a cinema verite documentary is not much more than an artist-approved promotional piece.

There had better be some laughs in a 600-page book, and Bell provides a fair share, often at the expense of Joan Baez. Every mention of Dylan’s onetime paramour is accompanied by some insult portraying her as a clueless, talentless, wide-eyed fraud. It’s mean, uncalled for and hilarious, but somewhat surprising given that Bell (accurately) points out Dylan’s own mistreatment of women in the words of his songs.

Any lingering sense that Bell has it in for Dylan dissipates by the time he reaches 1965-66, the apex of Dylan’s career. The story of the whirlwind 14 months in which he recorded Bringing It All Back Home, Highway 61 Revisited and Blonde on Blonde has been told countless times yet never ceases to amaze. Bell’s critical stubbornness remains a calling card even here. Ten pages spent on the virtues of the perfect “Visions of Johanna,” but not without slamming “Rainy Day Women #12 & 35.” (Good for him; the song is worthless.)

As with Bob Dylan concerts, the past few decades have seen a continuous stream of Bob Dylan books. Neverending Tour, meet Neverending Tomes. But even fans are overwhelmed by the number of quality choices, beginning with Clinton Heylin’s Behind the Shades Revisited, an update of what remains the most definitive biography. Since then there’s been Rotolo’s enlightening memoir, A Freewheelin’ Time; Greil Marcus’s The Old, Weird America; Sean Wilentz’s excellent Bob Dylan in America, which marvelously presents the singer as seen through the continuum of American culture; and Martin Scorsese’s documentary No Direction Home: Bob Dylan.

Once Upon a Time manages to nudge itself into this group by Bell’s sheer will of force. It might be hard for some fans to discover that Dylan wasn’t always where it’s at, at least in the way he presented himself to the world. But Bell’s thesis proves strong: Dylan’s musical oeuvre stands on its own. To buy into the legend might actually diminish its magnificence.