Rorate Coeli

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Rorate Coeli (literally "Heavens, drop down dew", meaning "Drop down ye heavens from above")[1] is the second movement of Amor Dei.


"Some more assured voices cite concrete images; a defined notion of God begins to emerge"[2]


Louis Niebur, in his book Special Sound, writes:[3]

   Bermange's initial directive to Derbyshire was to produce “the sound of a Gothic altar piece.[4] It was agreed that, unlike their first collaboration, "The Dreams", "Amor Dei" would, unusually, have no electronically produced sounds at all. All radiophonic sound would be derived from the sound of the human voice. In this, Derbyshire was guided by Karlheinz Stockhausen's Gesang der Jünglinge, one of the foundation works of electronic music, and a work Derbyshire admired.
   At the top of the first page of notes for this work is outlined the Dies Irae melody, but she quickly settled on a library recording of the more expansive Advent antiphon "Rorate Coeli desuper et nubes pluant justum" (Drop down dew, ye heavens, from above, and let the clouds rain on the just).[5]
   In her notes for the construction of this piece, she writed on the first day: “Take ‘rorate,’ make detailed analysis (serial, statistic and linguistic), rebuild a fragmented version, serially organized fragments of voice. Find best tech for cutting fragments: normal cut, switched, scanned, long cut, spaced fade up, etc. Very very fast at first in short groups, then in breathtakingly long complex dramatic sections.”[6] From these basic ideas, throughout the last weeks of May 1964, she began working with the prerecorded chant, first rerecording it, isolating each individual pitch as heard in music example 3.7.
   [...] She maintains the Dorian mode of the chant in the construction of her own melodies built out of the original recording, adding no chromatism not already present in the chant. This must have had an influence on her choice od “Rorate” in the first place, since it uses every pitch of the Dorian mode, then offering an easily sampled choice of each note. Music example 3.8 shows Derbyshire's original edit.
   Once she had isolated each pitch, she created a loop based on a reversed, filtered combination of several syllables, removing the consonants to create a smooth texture on one pitch. This looped single pitch was then used to re-create each pitch of the Dorian mode expanded to two octaves, created by matching each pitch to the Workshop's frequency counter. She divided the mode into three groups: the first group comprising the fifth E and B over two octaves; the second was a minor triad built on c#, F# and A, repeated an octave higher and completed with a final high C#; and the third was built out of the fourth D# and G#, also repeated an octave higher, as heard in music example 3.9.
   Having constructed three “tone rows,” Derbyshire then divided her mode into groups of two and three pitches each, moving stepwise up diatonically two octaves beginning with the lowest pitch, C#. She recorded each group as a tone cluster separately, working her way through all fourteen combinations up two octaves. Dynamics, qhile largely determined by the volume of the speaker's dialogue, were arranged according to six values, of six decibels difference between each, an influence she attributes to Stockhausen in her notes. Both the individual looped pitched and the clusters would serve as her final material for the broadcast, joining more heavily filtered and ring-modulated versions of individual pitches.
[Image of Delia's paper "Analysis 1 - Clusters"]


Amor Dei - 2. Rorate Coeli - Spectrogram.jpg




Delia's folder "RORATE COELI" contains 6 pages of her handwritten notes for this piece, and 4 sheets of her manuscript score.


  1. Rorate Caeli on wikipedia
  2. David Thomson's article Amor Dei: A Vision of God.
  3. Special Sound, chapter 3, pp. 105-107.
  4. Special Sound, ch.3, note 65: Briscoe, Radiophonic Workshop, 83.
  5. Special Sound, ch.3, note 66: "The original recording is labeled in the script for the work as "Plain Song Antiphon, unaccompanied. Back, band 1, Lib. No. LP 27101."
  6. Special Sound, ch.3, note 67: "Delia Derbyshire, undated notes. Delia Derbyhire Archive, Centre for Screen Studies, University of Manchester.