ON AUGUST 26, 1973, Joni Mitchell dropped by S.I.R., a rehearsal facility in Los Angeles, where her friend and fellow Canadian Neil Young was recording his legendary Irish wake, Tonight's The Night. Taking a break from that racket, Young and the Santa Monica Flyers backed Mitchell on one of her new songs, Raised On Robbery, a frisky boogie about love and larceny. She was "like a kid in a candy store", Nils Lofgren, one of the Flyers, said of that jubilantly unruly take, first issued in Young's Archives II and now the sole previously issued track in Joni's latest rarities box. "She kept saying, 'I've never played electric guitar with a band before.'"

In fact, as this 5-CD bounty reveals, the day before that S.I.R. lark, Mitchell had a rousing bash at the song - ultimately cut with more pop decorum on 1974's Court And Spark - in San Francisco, robustly strumming jangly electric guitar (or a rudely amplified acoustic) with ex-paramour Graham Nash and the rhythm section from his solo album, Wild Tales. And the year before, working on demos for 1972's For The Roses, Mitchell taped a version of that LP's playful seduction You Turn Me On, I'm A Radio with Young and his Harvest band the Stray Gators, jumping back and forth in dreamy come-hither and jolting, bluesy lust. "Just looking for the clarity of things," Mitchell claims in the linernotes of her three different passes at the song here - live and studio - before she found its final, breezy poise.

It's a mantra she might well have chanted every day on her way to - and through - the imperial peak covered in this instalment of Mitchell's Archives. For The Roses (sparingly detailed folk rock), Court And Spark (lush pop with jazz contours) and 1975's The Hissing Of Summer Lawns (emotional turbulence in fusion dynamics) remain her only Top 10 LPs in Ameri- ca. But Mitchell was in no rush to get there, preferring a voluntary exile from the road and record business deadlines - to a stone cabin on the Pacific coast of British Columbia - after the profoundly confessional triumph of 1971's Blue.

"It made me quite prolific," she tells Cameron Crowe in the booklet. "I was now alone and collaborating with nature" - a bond she cites in the opening lines of For The Roses ("I heard it in the wind last night/It sounded like applause"), featured in a first- step reading from December 1971 with the junkie's nightmare Cold Blue Steel And Sweet Fire. "Some- times I sat on a rock and tuned my guitar," an out-door exercise that produced the heartbroken physics in Electricity.

FOR THE ROSES was a race to closure, written in the wake of Mitchell's devastating break-up with James Taylor and in the shops by November 1972. Yet she spends all of Discs 1 and 2 in this set seeking the album's delicate negotiation of agony and tender assurance, often set in the fleeting pleasures and inevitable disappointment of the tour bus and after-show flings.

Taylor actually shows up at an April '72 studio date, playing guitar (with no small irony) in a test run of Electricity. And it's fascinating to hear Mitchell's instinctive certainty at work as she lays down a word- less guide vocal in Cold Blue Steel, mapping the tone and feel for Tom Scott's eventual soprano-sax solo.

Scott, in turn, was a pivot to Court And Spark when he invited Mitchell to see his group the L.A. Express in 1973, during their weekly residency at a jazz room called The Baked Potato. She hired the Express en masse for the record and subsequent touring. But where the first two Archives sets charted Mitchell's formative passage as a singer and writer, from public-domain ingénue to a "premier explorer [of] the tension bet- ween love and freedom" (Loraine Alterman, the New York Times, 1974), Volume 3 is an exhilarating helter-skelter of paths tested (the ruckus with Young) and inspirations refined like Mitchell's overheated vocal rapture at the end of a solo demo of Help Me, wisely dropped for the Top 10 single. The most remarkable find is a Piano Suite from the same '73 session that has Mitchell binding three songs for Court And Spark - Down To You, the title tune and Car On The Hill - in a solitary medley of wounds and warning that could have been a brilliant, contrary highlight of the LP.

The emphasis on experiment and process means there are fewer newly excavated compositions - Like Veils Said Lorraine, a For The Roses orphan; the modal- guitar reveries Sunshine Raga and Bonderia, the former with tabla and free-form trilling - but no less in the way of surprises. Mitchell had the swinging nugget Twisted, a 1960 smash for Lambert, Hendricks & Ross and the finale of Court And Spark, on deck for Roses, going a cappella over drummer Russ Kunkel's brush- stick sizzle. A March '74 concert with the L.A. Express opens with Blue's This Flight Tonight taking off in Nazareth-fusion gear. And even in a relatively quick sprint through the genesis of Hissing..., there is The Jungle Line au naturel (no Moog or Burundi percussion) and a long, look forward to Don Juan's Reckless Daughter in solo and pop-wise stabs at that 1977 double-LP's samba-school incantation Dreamland.

"I don't recall ever thinking, What's next?", Joni says, summing up the era for Crowe. "It's just not how my brain works. I just kind of go with the flow. Everything takes care of itself." Mitchell sang it this way on Court And Spark: "You can crawl, you can fly too... It all comes down to you." She is always looking for the higher road here - and getting there, step by step.