The trombone symbolizes the hereafter, the supernatural, hell and the underworld. Its powerful sound is supposed to conjure up images of the terror and unknown dimensions of these realms of darkness. Particularly in requiems (Mozart, Berlioz, …) the trombone section, often large, is assigned the role of evoking the audience’s fear of crossing over to the hereafter in the Dies irae and Tuba mirum. The symbolism is therefore religious.
The contrabass trombone’s particular power with its metallic elements is reminiscent of archaic brass wind instruments.