The Seven Stations of a Text of 1963 follow the prophet Jeremiah’s account in chapter 36: a text he dictated in prison passes there through different states. The improvisatory “Word” is followed by the “Dictation” as a three-voice canon of variants — the words of the Lord, the mouth of Jeremiah, the writing of Baruch. The “Reading in the Temple” rests on a pedal cantus firmus which, in augmentation, grows ever slower and weightier; the “oral report” has the freest form of all and bore the working title Étude; in the “Reading in the Chancellery” the same pedal melody shrinks into diminution. In the “Reading before the King”, who cut the book with a scribe’s knife and threw it into the fire, interruptions of the full Hauptwerk gradually devour the pedal melody, and the “renewed dictation” takes up the second movement and extends the ending with echoes, silences and a mighty last phrase. Zacher was concerned not with depicting the events but with the transformations a text undergoes; the unity of the text lies musically in the twelve-note row.
Szmaty of 1968 is dedicated to Isang Yun. He had invented his first graphic composition Tuyaux sonores for Zacher, but shortly before the première he was abducted from West Germany to South Korea on a false charge of espionage; to press for his release Zacher often played Tuyaux sonores or the Szmaty dedicated to him in public at that time. The title is the Polish word for rags and refers to the psalm verse “they parted my garments among them, and cast lots upon my vesture”. The Polish sounds stand for sonic properties of the organ: SZ for rustling, M for humming, A for resounding, T for spitting — the noise of speech in some pipes, especially clear in the staccato passage towards the end — and Y for dying away in the very highest register, which is traditionally almost never used on its own.
Vocalise of 1971 is a study for the swell pedal: over a sustained chord the louvre doors are operated to an exactly notated rhythm, so that opening and closing always take different lengths of time. Sharp rhythmic points are not perceptible because everything remains in transition; meanwhile the formant regions of the vowels unfold, A with the swell open, U or M with it closed. The resting chord consists of two interlocked peals of bells, and above this wave motion melodies made from the remaining six notes take place, sounding at times like Hebrew chant.
The title Diferencias of 1961 is borrowed from old Spanish variation cycles; the piece engages with the consequences of the concept of variation. There is no theme — the variations interpenetrate and constantly create new shapes. The ten movements are ordered by five characteristic tempi whose sequence can be read in several ways. In the Tranquillo movements Zacher invented the procedure of “intervalles-durées”, in which every interval receives a fixed duration of its own: Olivier Messiaen had earlier invented “sons-durées”, in which each note is given its duration, but Zacher wanted to avoid the predominance of whichever note was longest. Messiaen congratulated him on the work in 1961.
With John Cage’s Variations I Zacher arrived in 1966 at the invention of variable key pressure. Cage’s score consists of a sheet with about forty scattered points over which five further sheets, each bearing a single line, are thrown; the lines determine what the points mean — time, pitch, loudness. Since this is a composition with chance operations, Zacher found it consistent to let chance intervene in the interpretation too: he developed a scale from the normal attack through a loosening in which the pitch clouds and partials appear, to the most careful depression of the key at which scarcely a breath is heard — a risky technique balanced on half-opened valves. Cage was delighted, because no detail could be calculated in advance: the interpretation itself became a chance operation. Ré of 1969, finally, unfolds the properties of the note D over a pedal point: the voicer Ingo Vinck alters the speech of a large flue pipe with paper and card at its mouth, while in a low reed a krummhorn is tuned up and down. The recording was made from 4 to 6 October 2004; it received the Diapason d’Or in October 2005.