I arrived at Cologne Cathedral as the midday office was coming to an end. A pair of priests in red cassocks stood at the head of the nave, arms folded, like bouncers, only allowing through those who wanted to join the service. The brief ceremony ended with a voluntary from the organ, whose pipes are contained in a cabinet suspended improbably high up one side of the nave. I didn’t recognise the composer; I’m guessing mid-century, but it may even have been improvised. The music began quietly with vox celeste and grew from there. The sound – sinuous, slow polyphony and rich extended-tonal harmonies, darker than Messiaen’s sweet octatonicism – filled the building, which by the end positively rang like a huge stone bell.
I thought of Stockhausen, 20-something, sitting in this space, listening to music something like this (the modern nave organ wasn’t built then), dreaming of Gesang der Jünglinge. The resonance of the cathedral – full, massive – did things to the music’s space and time that surely must have inspired the swoops and swirls of Gesang, Kontakte and all the rest.