They got together at a Beverly Hills restaurant (with an outdoor terrace where she could smoke, of course), and Grand-Maitre presented his idea: a kind of jukebox ballet called Dancing Joni, leaning on audience favorites like "Both Sides Now" and "Chelsea Morning."

"Everything centered around this blonde, blue-eyed ballerina from Australia, and it was sort of dancing my life," Mitchell recalled. "But I thought, that's not important right now." Anyway, she had a better idea.

Grand-Maitre couldn't have known it, but after a hiatus of 10 years she had recently begun writing new songs. She was spurred on by something her grandson had said while listening to family fighting: "Bad dreams are good — in the great plan."

Mitchell was stunned. "How did he know that?" she wondered. "That's an amazing thing for anyone to know at any age. The line just stuck." When the war in Iraq began, her grandson's words resonated in her mind, and she "gave birth," as she described it, to four new pieces.

Grand-Maitre's invitation seemed like an opportunity to present that music in a new context. "Humbly I hope we can make a difference with this ballet," she told him, speaking of her outrage about the foreign and environmental policies of the United States. "It's a red alert about the situation the world is in now. We're wasting our time on this fairy tale war, when the real war is with God's creation. Nobody's fighting for God's creation."

That "short moment" he had requested turned into one of her inimitable all-nighters. And in the end the artistic director of the Alberta Ballet got more than he hoped for. Not only did Mitchell agree to the project, she took it over.

For the past several weeks, she had been sleeping by day and recording songs for her new album from dusk till dawn. If she had a spare moment, she scribbled notes about the ballet set. Music, art, dance: Mitchell calls it "crop rotation."

She is, of course, well past the stage of having to prove herself artistically. She is in possession of one of the most extraordinary song catalogs of the past half-century. Her chords break harmonic rules, have no technical names and defy Western musical theory. Her voice is an instrument that has grown sublimely heavier and huskier over the decades.

But she could not help being what she calls a "pot-stirrer." She thought about how the Maya calendar ends in 2012, about the 2004 tsunami and Hurricane Katrina. What, she wondered, what do you write at the end of the world?