Ligeti's mysterious and beautiful Lux aeterna (1966) for 16-part mixed chorus primarily varies between two textures: a surface of sustained, multi-timbral clusters that arise from polyphonically accumulated long tones, and short sustained consonant sonorities that give the effect of whispering.

Moving outward from a shared unison tone, the voices act individually to amass and develop close tetrachords which slowly modulate until reaching another unison (or octave) center. The work bears several remarkable features; for example, the word "Dominum" is first heard sung by three basses in falsetto voices, like an androgynous chorus of angels. The work demands excellent breath control from the singers; several entrances occur on high tones at piano and pianissimo dynamics, while other passages employ tones that must be sustained for extended periods (these notes are always doubled by at least one other voice so that subtle staggered breathing is possible). The work ends with the four altos on a major-second interval that dies out to nothing, followed by seven tacet measures which create a meditative silence to balance the work's restrained intensity.

Like Atmosphères (1961) for orchestra, Lux aeterna moves away from the pointed rhythmic style of Ligeti's earlier folkloric vocal music and angular orchestral works toward an even, smoothly developed surface texture. The eight-minute Lux aeterna is perhaps most familiar as the "voice" of the monolith in Stanley Kubrick's film 2001: A Space Odyssey; on its own, however, it suggests a pervasive universal presence rather than mere widescreen bigness.

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