This article originally appeared in the first edition of the Ultimate Music Guide published on May 19, 2017.

"That's the big difference between the performing arts and being a painter," muses Joni Mitchell, on a between-song introduction on her 1974 live album Miles Of Aisles. "Nobody ever said to Van Gogh, 'Paint Starry Night again, man!' He painted it, that's it..."

She might be an accomplished painter, but Mitchell has never treated her musical compositions as completed paintings. Instead she sees them as living entities, subject to expansion and development. Live recordings show how she has always radically reassessed her works- arranging songs for different instruments, altering her guitar tunings, shifting tempos, keys and time signatures. By the time Mitchell stopped touring in 1983, she must have got sick of having to rework her own musical masterpieces, but it would seem that her 1998 US tour must have whetted her appetite to have one last tilt at her legacy.

The result is Travelogue, where Mitchell chooses 22 songs spanning 30 years - most of them relatively little known album tracks-and orchestrates each of them grandly, slowing them down and delivering each in a hushed, poetic diction. It is usually seen as a companion piece to Both Sides Now, her 2000 album of jazz standards. Both were recorded at north London's Air Studios with a 70-piece orchestra arranged by Vince Mendoza, and both share some of the same personnel (including Wayne Shorter, a fixture of her albums since the late '70s, here using his soprano sax to pour liquid gold onto nearly every track). Both albums, it appears, were designed to fulfil her Warners contract - when the Warners imprint Reprise turned down Travelogue, Mitchell took it to Nonesuch, a more creative, artist-friendly wing of the Time Warner empire.

Ironically, the album of jazz standards sounds more like a classical album, while Travelogue is much closer to the exploratory spirit of jazz, tearing into its source material and radically rebuilding each song from the foundations up. The guitars that are usually an intrinsic part of Mitchell's songs have been completely excised, replaced by strings and woodwind that coo and growl, soothe and disrupt, solicit and rebuff.

The title of the album comes from a stray lyric ("Your life becomes a travelogue of picture postcard charms") from "Amelia", one of three tracks from 1976's Hejira that have been recast for orchestra. Addressed to the doomed pilot Amelia Earhart ("A ghost of aviation, she was swallowed by the sky or by the sea/Like me she had a dream to fly"), the original sounded almost airborne: all woozy pedal steel and heavenly vibraphone, flying, like Icarus, dangerously close to the sun. The Travelogue arrangement, though, takes us down to earth, as if Earhart had landed safely and was sharing incredible life stories with Mitchell.

"Amelia" is a perfect example of Mitchell's approach throughout Travelogue. Poetic imagery that might have got lost on the original song- the "six white vapour trails" of the six jet planes representing "the strings of my guitar" -are enunciated, sometimes arrhythmically, delivered like a declamatory poet, emphasised by gaps in the orchestration. And the orchestrations build upon ideas that were often only hinted at in the originals. It's something that seems to work particularly well on the tracks from Hejira, an album filled with spacious, modal, drumless explorations. The title track, "Hejira", works well as a slow-burning orchestral suite, with drummer Brian Blade providing a subtle propulsion. "Refuge Of The Roads" sees Joni's heavily chorused guitar recast on a harp and Kenny Wheeler's flugelhorn playing counterpoint to Mitchell's voice, while an Aaron Copland-ish string arrangement attempts to mirror the woozy fretless bass explorations of Jaco Pastorius.

With other classic albums, the orchestral treatment doesn't work quite as well. The two tracks from 1972's more minimal For The Roses- the title track and "Judgement Of The Moon And Stars" -have been so radically upholstered with bombastic Bernard Herrmann-style orchestrations that they have become virtually unrecognisable.

Travelogue was not a success. Not only was it the only Joni Mitchell album to not chart in the US, the UK, or even Canada, but the critical responses were generally negative. "The album sounds wrongly monumental," said Rolling Stone. "It does not swing or get loose... it translates Joni Mitchell as a scrupulously constructed puzzle." The New York Times was even more withering. "I personally have little use for the kind of bloated symphonic jazz heard here," wrote John Rockwell, dismissing its "soggy orchestralditherings" and comparing Mitchell's voice unfavourably to the Manhattan drag queen John Kelly's infamous Joni impressions. Many other reviewers also criticised what they saw as a radically altered voice, a product of Mitchell's 50-year addiction to tobacco, which she has famously described as "a focusing drug". "A husky shadow of former featherlight glory," said Betty Clarke in The Guardian. "If the health warning isn't enough to put you off cigarettes, the nicotine ravaged vocals of the once angelic, now gasping Joni Mitchell should."

The truth is that Mitchell's voice had been losing its upper register since the early '70s. By the time of her 1974 tour, many of the songs had already dropped by several semitones. The lowering in pitch is nowhere near as marked as with, say, Leonard Cohen - whose voice dropped by more than an octave in his final decades. Nor has it altered Joni's approach to her back catalogue as radically as Kate Bush, whose first few albums were so heavily based around that distinctive "falsetto" register that she refused to perform anything recorded earlier than 1985 on her 2015 comeback gigs.

Oddly, the very oldest song on Travelogue, "The Dawntreader", written in 1966, is taken in exactly the same key (D major) as it was on 1968's Song To A Seagull. The same is true of all three tracks from 1976's Hejira. There are only a few instances on Travelogue where the drop in pitch radically alters the whole mood of the song. When Mitchell originally recorded "Woodstock" with a Wurlitzer electric piano, on 1970's Ladies Of The Canyon, the crystalline purity of her voice seemed to feed into the song's sense of bright-eyed, hippie-era optimism. By 1974, live recordings show that she had already lowered the song from E flat minor down to B minor - as if the countercultural dream had already faded - while the Travelogue version takes us down to A minor, a whole flattened fifth lower than the original. It leads to a complete re-evaluation of the lyric: this hopeful paean to a reborn nation is now a lament to a lost age. The image of "the bombers riding shotgun in the sky... turning into butterflies above our nation" is less of a promise, more of a bad acid trip.

Likewise tile original version of "The Last Time I Saw Richard", from 1971's Blue, was in G major; the live version recorded on 1974's Miles Of Aisles took it down to E major, while Travelogue's version pitches us all the way down to B major-that's a massive downward leap of a whole sixth. On the original, when the self-pitying drunken ex tells us that he is "hiding behind bottles in dark cafes/Only a dark cocoon before I get my gorgeous wings and fly away", the Bukowski-bleak realism is undermined by Mitchell's light and playful delivery, all yodelling chirrups and warbles. Here the heaviness of the orchestral backing and tile texture of Mitchell's voice - less a soprano piccolo, more a cello-like contralto - actually seems to suit the darkness of the song.

There are other tracks where songs are improved by recontextualisation. The aforementioned "Dawntreader" gets an upgrade- with an elegant, modernist arrangement that highlights the poignancy of the lyric far more than the original. "Otis And Marlena", a quizzical miniature on 1977's Don Juan's Reckless Daughter, is turned into a suitably jerky baroque arrangement which rather suits the lyric, as it compares the elderly couples in Florida enjoying their mundane holidays, oblivious to the horrors of the world ("while Muslims stickup Washington").

Travelogue often works best when drawing upon the jazz sensibilities of its personnel. On 1982's Wild Things Run Fast album, "You Dream Flat Tires" is marred by some inappropriate cock-rock guitar and a guest vocal from Lionel Richie. Here it's slowed down and given a much more appropriate (and timeless) big-band swing treatment, complete with Nelson Riddle woodwind, muted horn blasts and a prowling Hammond organ from Billy Preston. "Be Cool", another track from Wild Things Run Fast, gets a similar big band setting, this time with a nod to Gil Evans, and with a tremendous piano freakout from Herbie Hancock. And "God Must Be A Boogie Man", originally a spartan, drumless duel between Joni and Jaco on 1979's Mingus, is here filled out for a full big band, with the strings filling in complex extended chords that were only hinted at in the original. Brian Blade's drums flutter, Shorter's improvisations are filled with sly references to the Charles Mingus canon, while Chuck Berghofer's double bass dances around the low end, imagining what Mingus himself might have brought to the track.

One thing common to all these versions is that they are much, much slower than the originals. Mitchell sometimes lags behind the beat, like Sinatra, and often lingers on phrases that take her fancy, like a poet. Indeed the two actual settings of other people's poetic writing here - "Love" (from 1982's Wild Things Run Fast, based on the popular King James Bible passage from the first book of Corinthians) and "Slouching Toward Bethlehem" (based on WB Yeats' "The Second Coming") - are perfectly suited to this environment. On the former, the Sketches Of Spain-style string backing draws attention to Joni's extraordinary melody, one that improvises over the chord changes as adventurously as Miles Davis might have done (it's fitting that Miles alumni Shorter is, of course, playing counterpoint on soprano). On 1991's Night Ride Home, "Slouching Towards Bethlehem" paired the dystopian Yeats lyric ("Things fall apart/The centre cannot hold") with a rather bland, folksy backing. Here it's given a suitably dramatic soundtrack treatment, all thundering timpani, growling strings and ominous woodwind.

As would befit an album that revisits old material, there is a strong element of nostalgia, and Mitchell seems to have deliberately chosen some lyrics that directly address the subject of ageing. "Just Like This Train" (from 1974's Court And Spark) sees the loose-limbed funk of The LA Express replaced by a slow, brooding, Carla Bley-inspired arrangement that turns the lyric into something that's less embittered and more resigned ("I used to count lovers like railroad cars... Lately I don't count on nothing, I just let things slide").

"Chinese Cafe/Unchained Melody", another track from 1982's Wild Things Run Fast, starts with a remembrance of adolescence ("We're middle class, we're middle-aged/We were wild in the old days, birth of rock'n'roll days"), but here moves from the wistful into the darkly heartbreaking. The line about giving up her child for adoption ("My child's a stranger/ I bore her but I could not raise her") takes on anew poignancy (she had not long been reunited with her daughter Kilauren Gibb, in a blaze of publicity), while the recurring musical quotation from the old Righteous Brothers single here serves like a Wagnerian leitmotif. Likewise "Cherokee Louise", from 1991's Night Ride Home, moves from uptempo melancholy of a teenage friendship ("Ever since we turned 13 it's like a minefield") and focuses instead on the mention of sexual abuse ("She runs home to her foster dad/He opens up a zipper and yanks her to her knees"). The strings and woodwind sound less like a pop orchestration and more like tile underscore ona particularly harrowing documentary.

The most moving evocation of time, however, comes in the closing track, "The Circle Game". It was a light campfire ballad on 1970's Ladies Of The Canyon, and a singalong favourite at live concerts, but here it mutates into a deliciously orchestrated epic, elevated by Wayne Shorter's dancing soprano sax. Again, the 59-year-old Mitchell can linger on poignant lines ("We're captive on the carousel of time"; "Cartwheels turn to car wheels through the town"; "We can only look behind from where we came", and so on) that the 26-year-old seemed to matter-of-factly sing with gusto.

The album would have made a suitable headstone for a remarkable career, and as was becoming a habit, Mitchell's interviews in 2002 certainly suggested that it would be her last. "I'm quitting because the business made itself so repugnant to me," she said, describing the record industry as "a corrupt cesspool". But once again, there would be further twists to come.