Theta

Theta θ is the eighth letter of the Greek alphabet and corresponds to the Latin letter “T”. (The composition is the eighth in the Music for Orchestra series and is dedicated to Teodor Currentzis.)
In geometry, theta θ is the symbol for calculating an angle. (The composition uses numerous angle calculations of ascending lines; in musical terms these are glissandi in Shepard scale movements.)
Theta θ as a character from the Greek alphabet symbolizes death.

Mahler's entire work seems to be characterized by a fascination with death, even a longing for death. In the summer of 1910, Alma Mahler reported, the only scores in Mahler's composing hut at his summer residence in Toblach were those from his complete edition of the music of Johann Sebastian Bach. Particularly noteworthy and apparently always had at hand by Mahler’s work were the cantatas such as “Come, you sweet hour of death” (BWV 161), “Haste to strike, oh longed fou hour” (BWV 53), “Dearest God,
when will I die” (BWV 8) or “Who knows how near to me my end?” (BWV 27). August 1910. Gustav Mahler is in Dobbiaco and is working on the 10th Symphony. His marriage is in crisis. He leaves a letter with the following poem he wrote on Alma's bedside table:

O sweetest hand that ever held me.
O dearest bond with which you weld me,
Take me but captive in your sensual clasp,
that as your slave I ne’er may flee your grasp.
O come to me sweet death in this, my hour of pain!
Spring up, o life-force, from my wounds again!
Toblach, 17 August 1910

Theta for orchestra sounds less specifically reminiscent of the score of Mahler's Tenth, but rather focuses on a primal tone of Mahler's longing for death.
“Come, Sweet Death” by the composer Johann Sebastian Bach, whom Mahler greatly admired, seems to set precisely this longing for death to music.

Come sweet death, come blessed rest!
Come, lead me in peach,
for I am tired of the world,
come, I am waiting for you,
come soon and lead me,
close my eyes
Come blessed rest!

This sacred song for solo voice and figured bass is transformed in Theta into a seemingly Mahlereque over-the-top opulence, mirrored symmetrically in the form of a palindrome (as it occurs again and again in the works of both Bach and Mahler) and undergoes a timestretching process making it practically unrecognizable. The melodic outlines of the song are blurred and distorted by glissandi – continuous sliding between the notes. The pietistic nature of the song is transformed and alienated into a hedonistic dance of death: “Come, sweet death!” not as a silent prayer but as an archaic primal scream.
The song "Come, Sweet Death" uses a descending melodic line in the upper voice, which is identical to the figure of a Baroque lamento bass. I hear Gustav Mahler's longing for death as the last lament of late romanticism, on the eve of the great upheaval into modernity: “death” as a symbol of catharsis at the dawn of a new world.
Today, a hundred years later, I once again understand “Come, Sweet Death” as a call for change in a new era. (Jay Schwartz).