Upon its 1965 founding, Chicago’s Association for the Advancement of Creative Musicians hit the ground running. If the genius quotient among the avant-jazz collective’s early membership (Anthony Braxton, Roscoe Mitchell et al.) was unusually high, the AACM’s flowering still owed much to the eagerness of local labels like Delmark to release its work. The group has long since dispersed across the country, but Pi Recordings has undertaken the admirable task of reuniting these far-flung talents under one roof.

In many ways, Vision Towards Essence is the crowning jewel of this campaign. Since 2001, the Brooklyn label has issued new discs by leading AACM ambassadors such as Henry Threadgill and the Art Ensemble of Chicago. This release, though, mines the very heart of the organization, offering a lengthy solo statement from its founder, Muhal Richard Abrams. The now New York–based pianist, who turns 77 on Wednesday 19, has always been better known for his mentorship than for his music, a fact that seems ever crazier as this sumptuous, frequently dazzling 1998 live set progresses. Largely forgoing thematic signposts, Abrams presents a continuous stream of ideas, but unlike his contemporary Cecil Taylor—another pianist who favors marathon solos—he rarely sounds frantic. The disc luxuriates in moods: mysterious, even creepy wisps of high notes; seemingly double-brained passages of playfully turbulent counterpoint; splashes of sassy stride. Vision Towards Essence sounds like a definitive statement, not only of Abrams’s improvisatory brilliance, but of the continued vitality of his Windy City–bred clan.