Long before "doing your own thing" became a blank check for mindless self-indulgence, Meredith Monk discovered the power of the totally liberated imagination. She was endowed, however, not just with daring and iconoclastic fervor, but also with an artist's creative fecundity, and sense of form.The consequence has been a series of innovative productions over more than a decade that not only put her in the front rank of the vanguard arts, but which have also left indelible marks on today's choreography, dancing, theater, filmmaking and music.

Monk has paid sporadic visits to Washington in the past -- too seldom and too briefly. Last night she returned to the Washington Project for the Arts with two colleagues to present a "concert."

The word is in quotes not because the event was in any sense a parody, but because Monk's way of making and performing music is so at odds with conventional expectations. Monk creates music "from scratch," so to speak, discarding virtually all culturally inherited notions of melody, timbre, scale, articulation and so forth, and reconstituting the whole activity from a "naive" standpoint. It's as if she has asked herself what it must have been like for the first human beings in caves when they strove to vent their feelings in grunts and howls and cooings, and how these inchoate mewlings shaped themselves into expressive utterance.

"Songs from the Hill," for solo voice and dating from 1975-76, was, though not the earliest, the most "reductive" of the compositions she presented last night. The sources of inspiration seemed to range from birdsong and other animal mimicry (the sounds of insects, for example) to primeval incantation. Like her other works, these songs involve incredible vocal virtuosity as well as startling invention.

Language, too, gets rebuilt -- Monk intones chains of syllables that coalesce into a strange new tongue, surprisingly comprehensible and eloquent. In "Vessel Suite," from her 1971 "opera epic" on Joan of Arc, and the recent version of "Tablet." Monk retraces the evolution of Western music, extending her palette to include instruments (electric organ, recorders) and polyhonic layering. But the same sense of archaic mystery and revelation remains.

Andrea Goodman and Monica Salem were her excellent collaborators. The concert repeats tonight and tomorrow at WPA.