A woman driving through the Brentwood section of Los Angeles on the last day of the city's 1992 riots pulled up behind a long, white luxury car paused at a stop signal. The pale automobile's license plate read "JUST ICE." And the woman, who happened to be one of the world's finest songwriters, couldn't help wondering if justice really was merely the means to be cold.

"I still believe in the power of the word, that words inspire," says Joni Mitchell, and in considering the proposition that chance and a traffic sign had placed before her, she later turned to Plato's "Republic", a philosophical discussion of moral ideas written and dramatized four centuries before Christ. "I also believe in the idea that the performing arts, including songs and plays, are capable of slowing people down and touching their souls in order to generate thoughtfulness. The premise of Plato's 'play' is the presentation of the argument that the strong do what they can, and the weak suffer what they must, debating if that's both true and fair."

In the act of exploring these and other related notions, Mitchell would create an inspiring, ten-song series of musical dialogues and playlets that comprise this autumn's "Turbulent Indigo" (Reprise, Due October 25), one of the most commanding statements of a peerless, seventeen-album career that has itself questioned most accepted precepts in popular music. "The arts are important part of cultural justice," says Mitchell, "and truth and beauty are the essence of their greatness, so artists, so artists have a big responsibility in every era to probe the rules by which we live, inquiring whether they serve us well."

By means of "Turbulent Indigo" material like "Magdalene Laundries" (named for the Irish work convents to which alleged disreputable women were given life sentences), "Not to Blame" (a pre O.J. Simpson parable of battered spouses), and "The sire of Sorrow (Job's Sad Song)," (based on the Old Testaments tale showing that suffering need not be associated with sin), Mitchell asks why the current quality of mercy is so strained, and why daily evidence of fairness is so elusive. And if pain in its many forms is the teacher that turns arrogance into humility and selfishness into sharing, how does one avoid the bitterness that short-circuits such lessons?

Each of these questions is at least as old as the Book of Job, and at a time when many insist that success and self-fulfillment should be standard rewards, such issues boil down to modern society's single most resounding demand: justice. We want it from our friends and enemies, from shopkeepers and public officials and the Supreme Court. And yet since Biblical times, the original and ultimate definition of justice was not institutional but personal.

Justice as displayed in Plato's "Republic" is the restraint of one's own selfish aims when they conflict with the well-being of others. Thus, until the day that each citizen is willing to do good while expecting absolutely nothing in return, there shall be no justice.

In musical spirit and emotional hue, "Turbulent Indigo most closely resembles Mitchell's landmark 1971 "Blue" album- a timely, stylistic irony, since the new record is her first in twenty-three years for Reprise, the label she left shortly after "Blue". And the resplendent pop motets that rank with "All I Want" and "A Case of You" for sheer unshakability are Joni's elevating cover of James Brown's 1986 "How Do You Stop" and "Sex Kills", with its shattering chorus regarding callous desire: "Sex sells everything/And sex kills."

"For the second time in recent historic memory, we have a sexually transmitted plague," says Mitchell. "Before the discovery [in 1928] of penicillin, the earlier scourge was syphilis, and the cultural response during Queen Victoria's reign [1837-1901] was a prudish conservatism, that made open pregnancy indiscreet and put long skirts on everything, including piano legs! Meantime, I'm told the London whorehouses were never so popular. Back then, the fearfulness created some public courtesies, but these days the family structure is rocking and nihilism is rampant among the young.

"But I don't like using scary or tragic chords in a heavy material like 'Sex Kills.' Music provides the emotional skeleton for a lyrical plot, and songs need to be more direct than poetry because the hybrid of pretty sounds and serious images creates pathos. So I try to lighten up melodically to open the listener's heart."

A native of Alberta, Canada, Mitchell was born Roberta Joan Anderson November 7, 1943, her adult surname being the result of a brief mid-sixties marriage to fellow folksinger Chuck Mitchell. At age nine, Joni contracted polio in an epidemic that swept her country, "and it was predicted that I might never walk again." Like Job, she resisted the temptation to curse the Almighty for her ill fortune, though she does recall screaming out Christmas carols in her hospital ward as a gesture of secular defiance. Regaining her health, she devoted herself to artistic modes of self-improvements, principally dancing, painting, and music. In 1967, she was signed to Reprise and recorded her first album with the guidance of longtime friend David Crosby, with whom she co-wrote the song "Yvette in English" on "Turbulent Indigo".

"The title song of the new record comes from a conference of the Canadian Council of the Arts that I spoke at in the early nineties" she explains. "The name of the conference was 'Making van Goghs,' and they said they wanted to focus on indigenous peoples, ethnic groups, and women. I opened my talk by saying you cannot make van Goghs,' and that artists can be encouraged or even groomed but not manufactured. Art is the result of experience, and van Gogh's despair and suicide are not what you'd want to duplicate." As Joni laments in the lyrics: "You wanna make van Goghs/Raise 'em up like sheep/...You see him with his shotgun there/Bloodied in the wheat/Oh what do you know about/Living in turbulent indigo?"

In other words, the pursuit of art, like the presence of justice, is a personal responsibility. Mitchell's latest acoustic guitar-entwined tour de force was coproduced with her estranged second husband, bassist Larry Klein, and includes guest appearances by Seal and textural/timbral jazz sax colorist Wayne Shorter. But its triumph of mood-cum-message--a brave blend of romantic faith and fervid realism--is her most devoutly individual discourse in a decade.

"I've never been a feminist, because I believe in male-female relationships without apartheid" she summarizes. "And I've never been a nihilist, because I continue to feel the heart is the healer."