"There were terrifying things in the air," said composer George Crumb in 1990, looking back at the world that inspired his haunting piece. "They found their way into Black Angels."

Black Angels is Crumb's jarring Vietnam War lament for string quartet. Responding to the media images of American involvement
in Vietnam brought into American homes each evening, Crumb attempted to capture in music the horror of the Tet Offensive, the My Lai Massacre and the stateside murders of Kent State protesters.

Since its premiere in 1970, the work's emotional power and unconventionality have inspired many chamber musicians. David Harrington, upon hearing it, founded the Kronos Quartet. For violinist Ron Blessinger, whose Third Angle New Music Ensemble will perform Black Angels this week, the work represents "tortured voices of the soul that we instinctively try to relate to." It's an apt turn of phrase for Crumb's isolated personal howl against man's inhumanity to man.

The work scored for "Electric String Quartet" (Third Angle's musicians will mike their instruments and use guitar amps) bubbles up from the blood mire of the war. From simulated whirring chopper blades ("electric insects") to plucks of Vietnamese folk music, the piece uses Vietnam, in Crumb's words, as a "parable on our troubled world." The finished score bears two inscriptions: in tempore belli (Latin for "in time of war") and the ominous "Finished on Friday the Thirteenth, March, 1970."

The latter isn't the only bit of ancient occultism that veils the work. Crumb sought to tap into universal archetypes, the spiritus mundi of man's spiritual consciousness. The subtitle "Thirteen Images from the Dark Land" hints at the overarching numerology that runs throughout. The work's trinity of movements--titled "Departure," "Absence" and "Return"--outline man's "fall from grace, spiritual annihilation and redemption," Crumb says. These titles are further divided into 13 brief fragments (the shortest is 40 seconds, the longest, just three minutes). Each fragment is dissected alternately into 13 or seven pitches within 13 or seven measures--13 and seven being the numerological equivalents of the Devil and God. For a final Good vs. Evil effect, there are moments throughout the score of ritual counting in a Pentecost of languages from German to Swahili.

The musicians bang gongs, bow water-tuned crystal glasses, trill their instruments with thimbles, glass rods and paper clips, and vocally click, chant and whistle. Quotes from Schubert's Death and the Maiden quartet, the Dies Irae from the Latin Mass and Tartini's Devil's Trill give us brief glimmers of conventional tonality. Though played without pause, there is a wealth of silence in Black Angels, and it's this silence that creates its unique tension and suspense.

The 15-minute work is undoubtedly unsettling. As Blessinger says: "It addresses our separation from God. We were on the wrong path and we had to confront our dark side to get back."

As difficult as it may be, Crumb's Black Angels tries to help us negotiate the journey.

LUCKY NUMBERS: George Crumb's Black Angels includes touches of the occult.Third Angle New Music Ensemble, First Christian Church, 13