Tournemire wrote L’Orgue Mystique between 1927 and 1932 for the Sunday and feast-day Mass of the Roman rite, in which the schola sang the Proper in its Gregorian setting. In the booklet Father Laurentius M. Schlieker OSB describes the place of the five pieces of an office in the service: the Prélude à l’Introït opened the celebration as an intonation before the Introit, the Offertoire followed the Offertory chant as a meditation, and the Elévation was played on quiet stops at the consecration, on themes from the Liturgy of the Hours of the day. The Communion accompanied the distribution of communion and the silence that followed, and after the blessing the Pièce terminale concluded the Mass as a large-scale symphonic piece.
Office No. 26 (La Sainte Trinité), dated 5 January 1929, belongs to the Cycle après la Pentecôte Op. 57; the feast, with its profession of the triune God, stands at the end of the Easter season. In the Prélude à l’Introït a pedal G is held for about 80 seconds; three and one run through all the movements as a stylistic device. The Triptyque, a three-part symphonic poem on the Vespers hymn “Iam sol recedit igneus”, the antiphon “Benedicta sit” and the “Te Deum”, for long stretches does without accidentals. Office No. 15 (Laetare), dated 18 January 1930 and from the Cycle de Pâques Op. 56, is for the fourth Sunday of Lent, on which the organ breaks its silence. In the Offertoire the cantus firmus is heard in rapid repeated notes like a Glockenspiel, and the Postlude Fantaisie on the Lenten hymn “Audi benigne Conditor” and the antiphons “Rabbi quid peccavit” and “Cum sublevasset” unfolds from a single flute melody spanning more than two octaves.
The two Sunday offices, also from the Cycle après la Pentecôte, date from the last months of 1931. Office No. 47 (XXe Dimanche après la Pentecôte), dated 30 December, revolves around exile: in the Offertoire on “Super flumina Babylonis” the organist’s hands move chromatically towards each other and cross. The Choral Alléluiatique N°. 5 on the Gradual “Oculi omnium” begins with reeds over pedal notes that remind Schlieker of the first heartbeats of a resuscitation, and expands into a toccata with echoes of the Alleluia of the Easter Vigil. In Office No. 43 (XVIe Dimanche après la Pentecôte), dated 4 November, for the first Sunday of autumn, the mood remains clouded; in the Offertoire a three-part canon of flue and reed stops enters twice. Only the Choral Alléluiatique N°. 1, with toccata figures over the cantus firmus in the pedal, dispels the darkness.
Sandro R. Müller recorded the fifth volume in July 1996 at the Liebfrauenkirche in Bottrop-Eigen, with Christoph W. Schulte im Walde and Marco Juvinale assisting with the stops. The organ, with three manuals and pedal, was built in 1929 by Ernst Seifert Söhne; from 1933 the workshop of Ernst Weyland in Leverkusen-Opladen looked after it and carried out all alterations.