For example, Lady Macbeth's "Out, Out, Damned Spot" soliloquy begins hypnotically, with her quietly terrified vocal lines repeatedly comforted by a beautifully voiced recurring chord for strings.
The fixed material included a recurring chord sequence ("Organs"), a melody like a skewed "Rockabye Baby" ("New Waltz") and an elegiac processional ("Virgin Complex"), while the freer passages were intensely physical yet fastidious.
At a time when most musicians were basing their improvised solos as well as their original compositions on the 32-bar, A-A-B-A popular-song format, with its recurring chord changes and clearly delineated choruses and bridge, "Ornette was going straight from A to Z, and nobody knew what hit them," Mr. Bley said.
He certainly uses it to sublime effect: the recurring Don Giovanni chord, the aria Martern aller Arten, the first strains of the Lacrimosa.
Indeed, the simple, recurring three-chord setting of the word "alleluia" is surely the most sadly beautiful harmonization of this timeless word.
He sounded best on "Charvez," a ballad by Mr. Hart with a recurring two-chord flourish; the song's inherent drama suited Mr. Iverson's declaratory instincts, and its modal progression prompted him to explore an insistent polytonality.
The soundtrack selections, most of them instrumentals lasting less than three minutes, are variations on a handful of chord progressions, recurring like a troubling memory.
The chords recur in countless guises and transformations to produce a meditative piece with passages of restless activity.
By scene's end, as Agnès wends her way toward a convulsive high C, the same chords recur in clipped bursts, their ferocity converted to her cause.
