"Adagietto" is the fourth movement of Gustav Mahler's Symphony N°5 (written in 1901-1902).
Herbert Karajan said once that when you hear this symphony, "you forget that time has passed". Intemporal beauty, deep and confused feelings blending desire and sorrow, inexpressible melancholy of longing, inner music of the soul and of memory: the Adagietto was chosen as a musical leitmotiv by Luchino Visconti for his masterpiece Death in Venice (1971), based on Thomas Mann's novella. The Adagietto can be heard at the beginning and at the end of the movie.
Listening to it, I cannot help remembering the final scene: Tadzio slowly vanishing in the light of the seashore, his hand directed towards the sun, while Gustav von Aschenbach is dying... Sublime scene....
Here is a mp3 version of the Symphony n°5 Adagietto, played by the SRW Sinfonieorchester conducted by Pierre Boulez