According to the composer, it is based on twenty years of improvising[1] at Église de la Sainte-Trinité, where Messiaen was organist since 1931.
Messiaen himself wrote that the work "corresponds almost exactly with the length of a low Mass, and its sections are intended to match with those of the service.
The music shows different aspects of the mystery of Pentecost, the Feast of the Holy Spirit.
"[2] The work was never officially premiered; Messiaen included it discreetly in the celebration of the Eucharist on the Pentecost Sunday of 1951 (13 May).
This passage is derived from the lines for flute and clarinet in Jardin du sommeil d'amour in Turangalîla-Symphonie; Messiaen described these as melodic "garlands" that resemble birdsong in slow-motion.