Olivier Messiaen's Messe de la Pentecôte (Pentecost Mass) for organ falls right in the middle of his stylistic development. It is a summation of techniques he used in improvising music for services at La Trinité in Paris, such as Greek and Hindu rhythms, and unusual combinations of stops, and it gives a foretaste of ideas that he would expand greatly in his later works, such as birdsong and the octatonic scale. It is not a mass consisting of the usual movements of the mass ordinary, but music to accompany those parts of the mass that are otherwise silent: the processional, the offertory, consecration of the Host, Communion, and the recessional.
The first impression of the work is that it is atonal, but closer examination reveals elements of plainsong and modal harmony. The opening "Entrée: Les langues de feu" (The Tongues of Fire), refers to the feast day itself and uses Greek rhythms contrapuntally to suggest lapping flames. Next is the "Offertoire: Les choses visibles et invisibles" (Things Visible and Invisible) featuring sharp, staccato Hindu rhythms and profound, resonating layers of sound punctuated by a Klaxon-like effect. The central "Consecration: Le don de sagesse" (The Gift of Wisdom) contrasts a plainsong motive with the Hindu rhythms. The timbres of the organ make the songs of the cuckoo, nightingale, and blackbird realistic in the atmospheric "Communion: Les oiseaux et les sources" (Birds and Springs). The final "Sortie: Le vent de l'Esprit" (The Wind of the Holy Spirit) employs a numerical technique in which the rhythm of the two lines of music, in contrary motion, increases and decreases incrementally, keeping the organist's hands flying over the keyboard. The song of the skylark is heard, along with the octatonic scale, which Messiaen referred to as his "Mode 2," used to simulate the power of the Holy Spirit, especially in the final chord that, including the bottom pedal point, covers nine octaves.