I couldn't look at people without weeping," Joni Mitchell said, about the time she wrote Blue, her best-loved album, which is 50 years old today. Like every aspiring literary sad girl, I know Blue by heart, though I have loved it for only 20 of its 50 years. I haven't been to California, either, nor did I live through the sexual revolution, or know the pain of giving up a child for adoption. Yet this album has seen me from childhood through to adulthood; its essence has fused with my own.

In her essay The Joni Mitchell Problem, Meghan Daum wrote of the album's unparalleled adulation: "The clause 'Joni and Me' has been written upwards of 10 million times, mostly in diaries with flowers drawn in the margins ... there is nothing original about being a late 20th-century-born female who feels that every life event ... was accompanied by a Joni song that was custom written for the occasion."

Please indulge me as I join the ranks. I first heard The Last Time I Saw Richard, the album's final song, after downloading it illegally from Napster on my father's computer (my apologies to Joni for this - though in my defence, it did prompt me to buy the album). In those days, it took over an hour to download a single track, so if it was a song you had never heard, you'd spend that time praying that it was worth the effort. I had chosen this song simply because my boyfriend at the time was called Richard. I was looking for something anguished and romantic that could speak to a 14-year-old who had just been dumped over MSN Messenger. I did not get that. Instead I got a work of such emotional complexity that my young heart could hardly digest it. "Richard got married to a figure skater, and he bought her a dishwasher and a coffee percolator ...": it was like a novel. And what was with the high, yodelling voice? This song said nothing to me about my life.

It was a valuable lesson to learn, that "resonance" is not the marker of a great work of art. Blue's genius, for me at least, lies in its subjectivity and its specificity. As Daum notes, Kris Kristofferson's advice to Joni to "save something of yourself" crops up again and again in anecdotes about Blue, but unless you are wedded to the confessional aspects of the album, it isn't actually all that interesting a comment. Even with a work as raw as Blue, we understand that the artist behind it has carved her pain into something outward; there will always be offcuts. Furthermore, as Daum points out, we never get to hear what Joni said in reply.

Blue's emotional intensity is part of its appeal, of course, but it tends to overshadow the fact that, when you are listening to it, you are in the presence of a great musician (a greater musician than Bob Dylan, incidentally, and one who is as much of a poet). But isn't that often the case with female artists? It all came pouring out of her: she simply bled on to the page, or the canvas, or into the mic. The genius involved in distilling the emotion gets lost.

The emotional intensity of Blue - and specifically, its femininity - is what puts a lot of listeners off. For an album that is so beloved, it is also one that is very easy to dismiss. Perhaps you never grow to love it, or perhaps, like Zadie Smith, you're actively resistant until one day - in her case, when she was 33 - it snares you: "When I think of that Joni Mitchell-hating pilgrim ... I truly cannot understand the language of my former heart ... how is it possible to hate something so completely and then suddenly love it so unreasonably?" These days, she writes, the album makes her cry. She experiences a "mortifying sense of porousness", just as Joni did while recording (she compared herself, at the time, to the cellophane wrapper on a pack of cigarettes).

In her essay, Smith goes on to explore the reasons for her own attunement to Blue. In her case it was a process of going from loving something to hating it in one fell swoop, but even for those of us who loved Blue at the outset, as the years go by I have felt myself undergoing my own process of attunement to it. What I mean is that I have grown to love it more, but in a way that is unashamed, overt. Sometimes when you are young it feels as though there is no greater crime than earnestness; by your late 20s, you tend to no longer give a toss. Nor do I care, as I perhaps once did, what men think of my love of Joni (besides, the best men have grown up, too, and appreciate her talent). And the lines that make me cry are different: it's Little Green that gets me now, as I mull over what it means to become a mother (or not).

Perhaps that's what makes great art: you don't just grow with it, you grow into it. Its meanings shift and twist. It was not that long ago that my mother and I were listening to Blue and I commented in an offhand way the flicking of the emotional switch that Joni makes in The Last Time I Saw Richard when she sings, "I'm gonna blow this damn candle out / I don't want nobody comin' over to my table / I got nothing to talk to anybody about." It seemed so bitter. "She's ventriloquising him," my mother said. And I felt the song anew.

I can't pretend to feel the same way that Daum or Smith feel about Blue. It doesn't speak to me in the same way it speaks to the poet Amy Key, who wrote beautifully in Granta of how it feels to live without romantic love. "I had always thought that in Blue Joni had taught me about love, about being in love and losing it," she wrote. "Now I think it's more that Joni taught me about longing. About the gap between what you want and what you have, and what you have and what you had wanted." And yet I feel a sense of communality with these women, who also love the thing I love, and who feel it deeply, in myriad ways. It is a gift.