Over the years, more than a dozen authors have written books about the life and music of Joni Mitchell. Yet, no one before Henry Alford thought to begin their tale with a story as tellingly arcane as the one that starts his new book I Dream of Joni.

The story begins in 2000, when Mitchell was being honoured with a concert in New York that saw stars like Elton John, James Taylor and Cyndi Lauper reverently performing her work. Seated in a skybox clearly visible to the entire crowd, Mitchell spent key parts of the show taking giant bites out of a ripe banana, a move that transfixed Alford, who was in attendance.

"You would expect that someone like Joni Mitchell, who writes such exquisitely sensitive lyrics, would herself be exquisitely sensitive to other performers and not do something as distracting as eating a banana while they play," Alford tells me by phone from his home in New York City. "At least that was my first thought. Then I thought, this actually makes perfect sense for a woman who has made an entire career out of being private in public. Then I had a third thought, maybe she just really likes bananas, at which point I realised that the author of the song 'Both Sides, Now' had just Both Sides Now'd me." Meaning, she had inspired Alford to look at his perception from every possible angle - up and down and win and lose - to try to understand something that will always remain unfathomable.

For his book, Alford found a decidedly quirky way to extend that mission. Subtitled "A Portrait of Joni Mitchell in 53 Snapshots", I Dream of Joni aims to crack the Mitchell code in 53 bite-sized chapters, comprised of revealing anecdotes, sly asides, and piercing insights, along with devastating quotes from the icon herself, often at other people's expense. Alford drew on earlier sources for much of his information - he didn't get to talk to the star himself - but his witty way into the material makes it all feel bracingly new. A long-time humourist for The New Yorker, Alford modelled his work on Craig Brown's eccentric 2017 book Ma'am Darling: 99 Glimpses of Princess Margaret. "He has a whole chapter in there that's nothing but Princess Margaret's citations in other books," Alford says.

The book's humorous tone doesn't only reflect Alford's sensibility but Mitchell's as well, an aspect of her character she's seldom given credit for. "People don't think of her as funny because she can be sanctimonious at times and entirely humourless at others," Alford says. "By the same token, this is someone who gets invited to Milton Berle's 80th birthday party, looks out at a room full of people with plastic surgery and chooses to perform her song 'Happiness Is The Best Face-Lift'!"

While the book's surreal form skips fitfully through Mitchell's career, it's anchored by a central question: what motivated her to create such a startlingly original, and wholly uncompromising, body of work? Naturally, key parts of that quest involve examining her relationship with her parents, most tellingly with her mother, Myrtle. In a seminal moment, Myrtle told a young Joni, "You've got to learn to control your emotions" - a shocking command to someone who went on to become what Alford describes as music's top "purveyor of searing self-disclosure".

As with every book about Mitchell, her mother comes off as jaw-droppingly judgemental. Throughout her life, Myrtle called her daughter "a quitter" for the simple reason that she stopped taking piano lessons as a child. Similarly, when Mitchell was about to take the stage at Carnegie Hall for the first time in 1969, her mother took one look at her outfit, a green-and-white plaid coat paired with a long sequin skirt featuring an artichoke and a bald American eagle, and said: "You're going on in those rags?" As if to certify her obsessiveness, Myrtle was also a compulsive cleaner. "She even vacuumed the garage!" Alford says. "That alone was enough to help fuel Joni's wildness."

As much as Mitchell may have rebelled against her mother's priggishness, she wound up mirroring her ease with flinging stinging put-downs of others, especially her fellow artists. In one chapter, Alford chronicles some of Mitchell's greatest zingers, including ones aimed at Crosby, Stills and Nash ("always out of tune"), Madonna ("what's the difference between her and a hard hooker?"), Jackson Browne ("a mini-talent, a phoney"), and several of the so-called confessional poets she is compared to, including Sylvia Plath ("morbid") and Anne Sexton ("a liar").

Hands down her most consistent target, though, has been the other greatest singer-songwriter of the last 70 years, Bob Dylan. Over time, Mitchell has called him a plagiarist, a fake and "a perverse little brat". Alford believes she keeps throwing barbs at Dylan, in part, because "it spurs her on creatively". Likewise, he thinks she talks and writes about her mother's critiques so often because "she understands the value of having a goad".

Alford traces an even more profound motivation for her work to the mid-Sixties when she had to give up a child because she was not ready to be a mother. At that time, abortion wasn't legal in her native Canada, and the birth control pill was hard to get; the only option was to give her baby up for adoption. For proof of how wounding an effect this had on her, Alford points to the fact that Mitchell began writing feverishly in the immediate aftermath of separating from her daughter and didn't stop until they were reunited in 1997. At that point, she didn't complete a new song for an entire decade.

Along the way, Alford's book includes chapters as inventive as one in which he compares Mitchell's spare use of punctuation in her Sixties lyrics to her rococo use of it in the Eighties, the latter distinguished by an alarming number of exclamation points and question marks. Crowded together on the page they look like musical notations but, to Alford, the frantic array of hieroglyphics offers "a perfect visual way to represent how awful that time was for her". During the Eighties, Mitchell suffered from multiple diseases, underwent major bouts of dental surgery, and experienced a major commercial downturn in her music.

Though Alford's search for Mitchell's motivations provides the book's primary motor, he often stops to mull the many fascinating contradictions in her character. One of the most persistent contrasts is her well-known distaste for writers and fans who examine her personal life with her compulsion to talk and write as much about her personal life as possible in songs and interviews. On her prickly relationship with the press, Alford says: ​​"There's this crazy tension in play of a person who rarely gives interviews, but when she does, they last five hours. Obviously, she's a talker and a revealer but afterwards she can feel burned."

It hardly helps that her relationships, particularly her romantic ones, have sometimes been cruelly used against her. An infamous Rolling Stone piece in the late Sixties featured a graphic charting a galaxy of her star lovers. Consider it perhaps the worst, early act of slut-shaming in rock history. Hardly one to let slights slide, Mitchell responded years later at an industry event by hurling a drink in Rolling Stone publisher Jann Wenner's face while calling him an asshole for good measure. Such risky acts, charming to Alford, are proof that "Joni Mitchell doesn't give a s*** what anyone else thinks", he says. "Ironically, I think that's one reason why she's so beloved."

Mitchell's unwavering commitment to honest expression has taken some of its most daring leaps in her lyrics. Yet, even when she has written highly revealing songs about famous exes, including Leonard Cohen ("Rainy Night House"), Sam Shepard ("Coyote"), and James Taylor (key parts of her For the Roses album), the beauty and insight of her words has made their subjects more appreciative than peeved. Notably, she has retained good friendships with nearly all of her former lovers, the sole exception being Jackson Browne. Alford believes this could be because he dumped Mitchell rather than the reverse, which seems to be the more common scenario.

In the 1990s, Mitchell wrote a scorched earth song about Browne titled "Not to Blame", in which she seemed to blame him for the suicide of his wife, Phyllis, while also rehashing a tabloid story about him allegedly physically assaulting his girlfriend of the time, actress Daryl Hannah. It's the sole attack of Mitchell's that Alford considers irredeemable.

Of all the ironies and contradictions examined in his book, perhaps the deepest corresponds to Mitchell's dearest subject: love. On the one hand, she has spent decades writing about her fervent search for what she once called in a lyric, "a love that sticks around". On the other, she has pined for freedom at all costs. "In that scenario, the shortness of her romantic alliances seems almost self-fulfilling," Alford says.

No doubt, Mitchell's resolute desire for independence is part of what has made her a role model for feminists. From her very first album, she was writing songs like "Cactus Tree", which reversed the cliche of the male-female dynamic by positing the woman as the one who will not be held down. At the same time, she often condescends to feminists and has often made clear that she prefers the company of men. "Her line is that she always found feminism to be 'too apartheid,'" Alford says. "'Why can't everyone work together?'"

No matter how divisive Mitchell's opinions might be, she remains defiant about them. For one thing, she's an unrepentant smoker who, seldom, if ever, acknowledges its health risks. In his book, Alford quotes her as saying that smoking cigarettes at age nine "was the best part of my childhood." She's equally intransigent in her discussions of race. Often, she has said that she feels like a Black man inside. To drive home her point, she appeared in Blackface on the cover of her 1977 album Don Juan's Reckless Daughter, a move she has never apologised for. "It may seem deluded," says Alford, "but she's not trying to piss people off. It's just how she feels."

Interestingly, the overwhelming majority of fans and critics have either given her a pass on this issue or even celebrated it, including prominent Black critics like the late Greg Tate. To Alford, that's just another intriguing part of the whole Joni gestalt.

By the end of his book, Alford concludes that Mitchell's contradictions aren't problems to be solved but dimensions to be celebrated. "Her contradictions are a huge source of texture in her life and work," he says. "They're part of what makes her so fascinating. Fans can spend hours marvelling over the fact that the same woman who wrote the anthem 'Woodstock', which urges us to go back to the garden, isn't a vegetarian, doesn't drive an electric car and doesn't like hippies! I don't find things like that hypocritical. I find them human."

'I Dream of Joni' will be published on 21 January by Simon & Schuster; Jim Farber is a writer and lecturer who teaches a course on Joni Mitchell at New York University in New York