Miles Davis liked to draw backstage, filling sheet after sheet with elaborately decorated steatopygous female figures, somewhat reminiscent of those painted by Mati Klarwein for his Bitches Brew album.

Joni Mitchell, we now learn, often had to be dragged away from her coloured pens and pushed out onto the stage to face the audiences she had been drawing from the wings, or the friends who had visited her in her dressing room. It might seem an odd or too-obvious comparison. Two first-name artists - everyone knows who is meant by "Miles" and "Joni" - one dark and notionally misogynistic, the other so pale as to be almost transparent, a feminist icon.

The similarities, however, are more interesting than the surface differences. Neither was a virtuosic technician: as a trumpeter Miles was no Dizzy Gillespie or Clifford Brown; Joni's ability to shape chords was limited by polio, though she overcame it. Miles was an intensely sensitive man, gender fluid and often unhappy, but also puckish and playful; his rages, one of which killed him, were defensive rather than hostile. Joni, who with Leonard Cohen seems the ultimate bedsit artist, was far from being a pushover and anything but solemn or sentimental. She sang a lot about love, but also warned in her greatest love song "be prepared to bleed".

And she had - probably still has - an amazing sense of humour, acknowledging the sheer absurdity of it all. When a guy in the audience on the live Miles Of Aisles album, "Joni, you have more class than Mick Jagger, Richard Nixon and Gomer Pyle combined", her laugh is one of the most beautiful sounds ever recorded. Not far behind her offstage vocal - did the audience know what was happening? - behind Neil Young on "Helpless" at the Band's farewell concert.

Here's the big relevant difference between Miles and Joni Mitchell. His paintings sell in galleries for thousands of dollars. Joni's drawings were pasted up in books to give to friends and lovers, and now they're available to all of us as gifts to Joni-loving friends and partners. Important, too, is that they're drawings, not of abstract anthropological fantasy figures but of real people. The audience paintings do have an abstract cast because, with her eyes, they must have seemed a bit of a blur through the curtains. But the portraits of actual friends are startlingly accurate and revealing.

She has Neil Young's stare and curiously militaristic fashion sense down to a satirical 't'. Graham Nash is portrayed three times, with ever denser detail and colour, as if she is coming to know him at the end of her pens. David Crosby has an empty space where his brain ought to be: is she making a point, or a joke? Familiar titles appear. Court And Spark, the album that saw her move towards something like Miles's jazz fusion, is a strange biomorphic form in the landscape, reminiscent of Georgia O'Keeffe, who is also portrayed. "This Flight Tonight", one of her most famous songs, even after it was covered by Scots rockers Nazareth, shows an engine nacelle in a thunderstorm, not the way we usually hear the lyric. And there's a solitary self-portrait, done in a mirror while sketching, unforgiving in its reflection of the over-large teeth and Sami cheekbones.

It was a not uncommon fate among female songwriters - Laura Nyro and Carole King are obvious examples - to see their work covered by others. Mitchell emerged as a significant writer when her idol Buffy Sainte-Marie covered The Circle Game and Dave Van Ronk and Judy Collins both recorded Both Sides, Now. It was on the back of that success that she was able to make Song To A Seagull. She didn't make much money, though, until Blue established her as a bestselling name artist, and as she approached the Christmas of 1971, she found that she was moving in circles that didn't quite sit with her own ongoing poverty.

In the intro to Morning Glory On The Vine she refers to her friends as "nouveau riche", which probably means the same thing to a non-francophone Canadian as it does to us. Her solution was to write out her lyrics in neat cursive and accompany them with drawings from the road. The book was made up, passed out and then largely forgotten until Mitchell went to visit friends who had been burned out of their home. She was touched to see that her present was one of the things they had rescued from the flames, and the idea came to make it more generally available.

Her active career is now effectively over, and there's an assumption that it ended because of ill-health. Joni's hospital bulletins have almost become a sub-genre, and a curiously macabre one, except that they reflect her own intense physicality and self-awareness. Being prepared to bleed, as she sings in A Case Of You, is part of being alive and being a woman. Her career was precisely bracketed by the birth of a child in 1964, given up for adoption and not publicly known until 30 years later, and then by her meeting with that daughter, Kilauren Gibb, in 1997.

She made a couple of albums after that, divorce-tinged songs relating to her break-up with Larry Klein - her professional name came from first husband Chuck Mitchell - and they're decent enough, if not classic, but Joni said that she had lost interest in writing new material after meeting Kilauren. It was as if songwriting and being a mother were connected and sublimated through all her most creative period.

The lyrics included in Morning Glory On The Vine come from the moment just before her breakthrough, but include some of her most celebrated work: Big Yellow Taxi is now an anthem of the environmental movement, Woodstock was reprised in 2019 to mark the fiftieth anniversary, while Ladies of the Canyon, a Joan Didion novel in miniature, reminds us that golden California wasn't just guys in spear-point shirts and gold chains, racing round in cars, but also women, waiting and making do, and cracking wise up in the hills.

Roberta Joan Anderson, from Fort Macleod, Alberta, and of Scots-Irish-Norwegian stock, evolved slowly into a persona as elaborately constructed and defended as "Billie Holiday", but without the tragic mask. Joni's first jazz model was actually London-born but Scottish-blooded Annie Ross, though she later grew to admire Miles Davis ("Just the way he walked was cool") and Edith Piaf, of whom I can vouch she did a hilariously accurate impression.

Whereas all of these artists had well-publicised and mythologised drug and alcohol habits, Joni had ailments. This is non-trivial. We were never allowed to see her as anything other than a physical person, frail but somehow self-protecting, seemingly lightweight but super-tough. It's perhaps no accident that her most celebrated "illness" was Morgellons syndrome, a self-diagnosed and seemingly delusional parasitosis that in Joni's case manifested in the belief that her skin was exuding mineral fibres. Some people think they're infested with bugs. Joni spent her life creating and shedding a body armour. You can hear in these songs and see in these pictures that what she understood better than anyone is that we're all frail carbon units, beautiful but easily scratched and bruised, prisoners of biology and art. Both sides, now.