The greatest single composition of the 20th century

i would like to nominate Messiaen's "Quartet for the End of Time" as the most profound, complete and musically satisfying work written in the 20th century.

here are some program notes for this work, courtesy of University of Southern California :

MESSIAEN: Quartet for the End of Time

Program Notes

In 1940, Olivier Messiaen (1908-92) was interned in a German prison camp, where he discovered among his fellow prisoners a clarinettist, a violinist and a violoncellist. The success of a short trio which he wrote for them led him to add seven more movements to this Interlude, and a piano to the ensemble, to create the Quartet for the End of Time. Messiaen and his friends first performed it for their 5000 fellow prisoners on January 15, 1941.

If the plain facts of the work's origins are simple, the spiritual facts are far more complex. Messiaen's religious mysticism found a point of departure for the Quartet in the passage in the Book of Revelation (chapter 10) about the descent of the seventh angel, at the sound of whose trumpet the mystery of God will be consummated, and who announces "that there should be time no longer."

According to the composer, the Quartet was intended not to be a commentary on the Apocalypse, nor to refer to his own captivity, but to be a kind of musical extension of the Biblical account, and of the concept of the end of Time as the end of past and future and the beginning of eternity. For Messiaen there was also a musical sense to the angel's announcement. His development of a varied and flexible rhythmic system, based in part on ancient Hindu rhythms, came to fruition in the Quartet, where more or less literally Messiaen put an end to the equally measured "time" of western classical music.

The architecture of the Quartet is both musical and mystical. There are eight movements because God rested on the seventh day after creation, a day which extended into the eighth day of timeless eternity. There are intricate thematic relationships, as for example between movements two and seven, both of which are about the angel; and stylistic and theological relationships, as between movements five and eight.

In a preface to the score, Messiaen commented on each of the movements:

1.

Liturgy of crystal. Between three and four o'clock in the morning, the awakening of the birds: a blackbird or a solo nightingale improvises, surrounded by efflorescent sound, by a halo of trills lost high in the trees...

2.

Vocalise, for the Angel who announces the end of Time. The first and third parts (very short) evoke the power of this mighty angel, a rainbow upon his head and clothed with a cloud, who sets one foot on the sea and one foot on the earth. In the middle section are the impalpable harmonies of heaven. In the piano, sweet cascades of blue-orange chords, enclosing in their distant chimes the almost plainchant song of the violin and violoncello.

3.

Abyss of the birds. Clarinet alone. The abyss is Time with its sadness, its weariness. The birds are the opposite to Time; they are our desire for light, for stars, for rainbows, and for jubilant songs.

4.

Interlude. Scherzo, of a more individual character than the other movements, but linked to them nevertheless by certain melodic recollections.

5.

Praise to the Eternity of Jesus. Jesus is considered here as the Word. A broad phrase, infinitely slow, on the violoncello, magnifies with love and reverence the eternity of the Word, powerful and gentle, ... "In the beginning was the Word, and Word was with God, and the Word was God."

6.

Dance of fury, for the seven trumpets. Rhythmically, the most characteristic piece in the series. The four instruments in unison take on the aspect of gongs and trumpets (the first six trumpets of the Apocalypse were followed by various catastrophes, the trumpet of the seventh angel announced the consummation of the mystery of God). Use of added [rhythmic] values, rhythms augmented or diminished... Music of stone, of formidable, sonorous granite...

7.

A mingling of rainbows for the Angel who announces the end of Time. Certain passages from the second movement recur here. The powerful angel appears, above all the rainbow that covers him... In my dreams I hear and see a catalogue of chords and melodies, familiar colours and forms... The swords of fire, these outpourings of blue-orange lava, these turbulent stars...

8.

Praise to the Immortality of Jesus. Expansive solo violin, counterpart to the violoncello solo of the fifth movement. Why this second encomium? It addresses more specifically the second aspect of Jesus, Jesus the Man, the Word made flesh... Its slow ascent toward the most extreme point of tension is the ascension of man toward his God, of the child of God toward his Father, of the being made divine toward Paradise.

i hope there are other nominations on this thread.