The texture of a dream is crowded with details. None is anticipated; each always surprises. Its logic remains hidden as wishes are fulfilled; all senses are assaulted and soothed at the same time. And hours are suspended as if only seconds pass. The music of Philip Glass has all these qualities, and the concert by the Philip Glass Ensemble at the Pension Building Saturday night was beautiful.

The first three sections of "Music in 12 Parts" opened the program in a powerful parade of Glass' compositional devices. A simple sustained dialogue of F-sharp and C-sharp was immediately veiled in an additive process of two- and three-note figures from flute to saxophone to electric organ and back. Timbres dropped in and out unannounced, a cascade of eighth notes remained constant, and the momentum only grew. There were no rests, there was no silence. The demands on the players' virtuosity were almost cruel, and the effect was staggering.

Glass, Michael Riesman and Dora Ohrenstein caressed the keyboards, Richard Peck sustained a golden purity in his saxophone, flutists John Gibson and Jack Kripl's stamina was surpassed only by their impeccable musicianship. Ohrenstein's mezzo softly peered behind Peck's saxophone, later weaving through the score in a crazed fioritura that fell somewhere between scat and bel canto -- yet unlike most that has been heard in Western music before Glass.

Reactions to Glass' music tend toward extremes: Either one gives into it totally, or experiences exasperation and disbelief. In part three, a ferocious dance was suggested by the saxophone, patterns emerged and vanished in the vast acoustical space mixed with clarity and Wagnerian loudness by Kurt Munkacsi. The quickening pulse of the music matched that of the listener.

It was with an "Einstein" encore that the ensemble closed the evening as the enthusiastic crowd cheered the "Spaceship" scene that ends the most exciting American musical drama of this and many other generations.