LOS ANGELES — Joni Mitchell, despite her introspective reputation, has always been a dancer. At a disco during the '80s, she encountered a music critic spouting invective. But after watching her dance, he asked for a lesson. "I told him to close his eyes and center his weight on his body with his feet astride," she recalled. "And I said: 'Relax your body. Keep your eyes closed. Feel the beat. Express how much you enjoy that beat with your body and forget what you look like."'

Two decades later this legendary singer-songwriter is still giving dance lessons: "The Fiddle and the Drum," her choreographic collaboration with the Alberta Ballet, opened on Feb. 8 in Calgary, Canada. Meanwhile, "Flag Dance," an installation of her anti-war mixed-media art, has finished a two-month run at the Lev Moross Gallery in West Hollywood, and she has recently recorded enough new songs for an album, which she plans to call either "Strange Birds of Appetite" or "If."

"I'm working three shifts," Mitchell, 63, said. "I'm doing the work of four 20-year-olds. Between the art show and the ballet and the new album, I've never worked so hard in my life."

She was seated at an outdoor table at La Scala Presto, a modest Brentwood trattoria. Los Angeles was hitting a slight cold snap, but under the heated lamp Mitchell could smoke in relative comfort, perched in front of a suburban parking lot, where they had doubtlessly paved paradise. We were having an early dinner, which for her is more like breakfast. She started with two cappuccinos and lemonade, warning me, "I'm a night owl. I'll outlast you."

Mitchell speaks as she sings, lilting up and down in bars of her native Saskatchewanean speech. But she insists on depth, on full attention and on sincerity, her "jive detector" on constant high alert. "I don't like being too looked up at or too looked down on," she said. "I prefer meeting in the middle to being worshipped or spat out."

Over the course of a dozen or so hours of a wide-ranging conversation, she gets to talking about how her new interdisciplinary project began: with a curious letter she received last year from one Jean Grande-Maitre.

"Please forgive my somewhat imperfect English as I am a native of Quebec and I am still brushing up on this new language," it read. "Next year will be Alberta Ballet's 40th Anniversary Season and as Artistic Director, I would be enthused by the possibility of choreographing a ballet to your brilliant and profoundly moving music.

"I would really love to fly to Los Angeles," it went on, "and meet you personally for a very short moment."