The Art Ensemble of Chicago began its extraordinary performance at the Ninth Street Festival Saturday night in prayerful meditation: A gong reverberated throughout the National Building Museum's Great Hall. The rustle of percussion was heard. Joseph Jarman's flute and Roscoe Mitchell's alto sax gently entwined, hovering over Malachi Favors Maghostut's probing bass lines. Lester Bowie added a susurrant trumpet blues line. Then, as the tribal-painted Famoudou Don Moye exerted himself behind the trap drums, flanked on both sides by racks of chimes, gongs, bells, clappers--all manner of wood, brass and skins--the music erupted. From then on, the mood was that of vibrant celebration and ceremony, very much in keeping with the ensemble's slogan: "Great Black Music--Ancient to the Future."

That musical continuum was expressed in often jolting terms. Tumultuous African drive cross rhythms, played by the entire ensemble, were juxtaposed with passages of joyous swing or playful bop, or other worldly sounds that suggested music to come. Depending on the mood of the moment, each of the musicians had much to contribute, especially Moye, whose multifaceted percussion gave the ensemble its enormous momentum.

But if there was one highlight, it was Roscoe Mitchell's performance. His alto playing was graced by unusual clarity, and the hefty swagger he demonstrated on both tenor and bass saxophones was something any jazz fan could immediately appreciate.

The Ninth Street Festival continues next Saturday with the George Coates Performance Works Company.