An opera exploring the frisson of the radical politics and aesthetics behind the emergence of Chicago’s Association for the Advancement of Creative Musicians would be trenchant at any time. Launched by visionary pianist/composer Muhal Richard Abrams in the spring of 1965, the organization became a fulcrum and forum for some the era’s most adventurous artists, including Henry Threadgill, Anthony Braxton, and Jack DeJohnette.

Trombonist, composer, installation artist, computer music pioneer and scholar George Lewis joined the AACM at the age of 19 in 1971, and the Cal Performances presentation of his Afterword, an opera on Friday at Zellerbach Playhouse as part of Ojai at Berkeley festival feels particularly timely. Last week word came that Mills College is set to eliminate the position of reed explorer Roscoe Mitchell, who founded the epochal Art Ensemble of Chicago with fellow AACM members Lester Bowie, Joseph Jarman, Famoudou Don Moye, and Malachi Favors in the mid-60s.

“It was a genius hire, and would be a boneheaded separation,” says Lewis, the Edwin H. Case Professor of American Music at Columbia University. He holds deep affection for Mills, where he’s taught intermittently over the past 30 years and met his wife, koto master Miya Masaoka. A letter writing campaign spearheaded by former and present students of Mitchell’s speaks to his pervasive influence and his essential role in maintaining the college’s vaunted reputation as a hotbed of musical experimentation.

It was during a stint teaching at Mills that Lewis met Ojai at Berkeley’s artistic director, pianist/composer Vijay Iyer, a disaffected Cal physics grad student who was delving increasingly deeply into the Bay Area jazz scene. He was ready to abandon his academic career when CNMAT’s David Wessel introduced Lewis to Iyer, who ended up recruiting the trombonist to play on his 1995 debut album Memorophilia (AsianImprov).

He also asked Lewis, who was then a professor at UC San Diego, to sit on his interdisciplinary PhD thesis committee, which also included composer Olly Wilson and Nobel laureate Donald Glaser (who invented the bubble chamber used in subatomic particle physics). The dissertation, Microstructures of Feel, Macrostructures of Sound: Embodied Cognition in West African and African-American Musics, “is extraordinary, a wonderful contribution to neuroscience literature,” Lewis says.

“Everybody reads and cites it, though it hasn’t been published. Looking at improvisation and embodiment and West African music, he did computer simulations as proofs. Vijay’s got this incredible charisma. He finds these people even younger than himself and creates new communities and new subjectivities. It makes sense for him to be artistic director of Ojai, He’s transformed what people think Ojai should be about.”

Ojai at Berkeley kicks off tonight with Lewis and Iyer playing a duo piece in tribute to Wessel, a last minute addition to the program due the illness of trumpeter Wadada Leo Smith (another AACM veteran). The program runs through Saturday. For Friday’s Bay Area premiere of Afterward, an opera, the production features soprano Joelle Lamarre, contralto Gwendolyn Brown, and tenor Julian Terrell Otis with the seven-piece International Contemporary Ensemble (ICE) conducted by Steven Schick.

The work is based on Lewis’ magisterial book A Power Stronger Than Itself: The AACM and American Experimental Music. While the libretto draws extensively from tapes made at early AACM meetings, Lewis wasn’t interested in creating larger than life characters for his opera. Instead, he sought to create avatars that represented various positions and ideas, “archetypes without stereotype.”

“A lot of people have the idea that great art comes from heroic individuals sitting in garrets,” Lewis says. “I believe it comes from communities of people who come together, particularly suppressed communities that need to come up with creative solutions. You have to find out who the choir is and start preaching to them, work out solutions and start supporting one another.”

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The music is full of the sense of discovery, marked by conflict and consonance, garrulous debate and disonance, affectionate phrases and striking harmonies. Lewis evokes a protean moment when artistic and political identities take shape, leading to a flood of music that has lost none of its intellectual and aural impact. Like many of his AACM peers, Lewis continues to produce bracing new work, like a piece that’s on the Korean Gugak Creative Orchestra’s October 28 Cal Performances program at Zellerbach.

“I don’t consider myself a creative writer,” Lewis says. “I’m an academic writer, but the method of the opera, I talk about James Clifford, idea of re-staging quotations, which is standard in academic research. You find yourself locating and crafting a narrative. In this case it’s not linear. These are situations that AACM people faced very young, moving into unknown waters.”