Composed: 1963-65

Length: c. 27 minutes

Orchestration: 3 flutes (2nd and 3rd = piccolo), 3 oboes (3rd = English horn), 3 clarinets (= E-flat, bass, and contrabass clarinets), 2 bassoons, contrabassoon, 4 horns, 4 trumpets, 3 trombones, tuba, percussion (Basque drum, bass drum, glockenspiel, side drum, suspended cymbal, tam-tam, whip, xylophone), celesta, harpsichord, harp, strings, soprano and mezzo-soprano soloists, and two mixed choruses

First Los Angeles Philharmonic performance: April 18, 1998, with Esa-Pekka Salonen conducting, soloists Sibylle Ehlert and Elizabeth Bishop, and the Los Angeles Master Chorale

György Ligeti is a nonconformist through and through. The hostility toward the musical past his avant-garde peers once proclaimed has always been alien to Ligeti, however profoundly his own music undermines the stable building blocks of that past. He embraces a ceaseless curiosity and quest for reinvention.

And yet his musical voice has an instantly recognizable and unique signature. The Requiem, premiered March 14, 1965 in Stockholm, consolidates some of its characteristic features.

Most immediately striking is the way in which Ligeti supplants our traditional expectations of melody, harmony, and even rhythm with mesmerizingly thick, cloudlike textures of sound that unfold continuously. More than mere "color," these become the actual musical substance, with an effect of space expanding as our sense of ordinary time is transcended.

Such is the music we encounter immediately in the first two of the Requiem's four sections. The work sets only a portion of the traditional texts from the Mass of the Dead. Its opening Introit gives the impression of rising from the grave as its sepulchral registers only gradually allow for a ghostlike ascent from the nether regions. The following Kyrie section elaborates a classic working out of Ligeti's trademark technique of "micropolyphony," in which individual voices become so densely woven together that only the seamless, cluster-like blends they together form can be discerned.

The Kyrie is constructed as a vast fugue (with a gentler middle section for the Christe) in which Ligeti subdivides the five main vocal sections (soprano, mezzo, alto, tenor, and bass) into four strictly chromatic strands each, according to his own complex system of rules. Instead of a pattern of recognizable lines of melody with a steady pulse, what results is an awe-inducing, vertiginous accumulation of sonic movements that seem to spread almost like a liquid.

The Requiem's final two parts are both from the famous Judgment Day sequence, whose title, Dies Irae, is given to the first (also the longest section of the whole Requiem). Ligeti describes this as "the center of the work" and refers to his inspiration from such visual sources as Brueghel the Elder, Bosch, and Dürer. It suddenly shifts the temperature into something "hysterical, hyperdramatic, and unrestrained" (the composer's characterization).

With the Dies Irae, we encounter another key facet of Ligeti's musical personality: an extraordinary juxtaposition of terror with an outlandishly Rabelaisian sense of humor that revels in extremities of timbre, range, and volume. This is the Ligeti who perceives the traditional Latin text of the terrible last days as something akin to the contemporary mythology of the comic strip cartoon. The soprano's absurd coloratura calls to mind a Queen of the Night on acid. The Dies Irae foreshadows Ligeti's great "anti-opera" of apocalypse from the following decade, Le Grand Macabre, where the dead come back to reclaim the living.

The Lacrimosa returns to the relatively homophonic texture of the Introit, foregrounding the otherworldly beauty of the two solo female voices as they spark prismatic harmonic auras off each other and the orchestra. With its pregnant pauses and meditative air, the Lacrimosa offers a vaguely unsettling air of closure to the Requiem - salvation is unattained. "One dimension of my music," Ligeti has observed, "bears the imprint of a long time spent in the shadow of death."

- Thomas May is a senior editor at Amazon.com. His book Decoding Wagner is available from Amadeus Press, which will also publish his latest project, The John Adams Reader, in June.