FamousChord in fourthsTechnique de mon langage musical, 1944 · Olivier Messiaen
Technique de mon langage musical, chapter XIV (vol. I p. 50; vol. II Ex. 213), with mode 5 in Ex. 214, its melodic formula in Ex. 215, and Ex. 216 quoting 'Vocalise, pour l'Ange qui annonce la fin du Temps' (Quatuor pour la fin du Temps, 1941), where chords in fourths alternate with chords of resonance; repeated in the mode 5 chapter (Ex. 349). Shorter forms in 'Regard de l'étoile' (Vingt regards no. 2) and 'Regard de l'Onction terrible' (no. 18).
Six notes stacked in fourths that take turns between the wide, tense augmented fourth and the plain perfect fourth, starting with the augmented one. Messiaen built it so that its notes are exactly one of his modes, and it hangs in the air with no major or minor feel at all. He uses it in the 'Vocalise' of the Quartet for the End of Time, trading it with his chord of resonance.
Also called fourths, accord en quartes, chord of fourths, Messiaen's quartal chord
Sources: Melody Chan, 'A Study of Influence, Structure, and Performance in Messiaen's Préludes (1928-29)' (DMA thesis, University of Toronto, 2015) · David Rogosin, DMA thesis on Messiaen's Vingt regards sur l'Enfant-Jésus (University of British Columbia, 1996; file ubc_1996-091554, copy on Scribd) · Sercan Dere and Onur Nurcan, 'A multi-dimensional analysis of a modernist work composed in captivity: Olivier Messiaen, Quartet for the End of Time', EJMD 23 (2023), 195-228 (doi 10.31722/ejmd.1260122)