This has been one of my favourite organ pieces for the longest time. I was first introduced to this piece upon watching smalin’s music animation video. The counterpoint and harmony is just sublime.
One of the biggest challenges of arranging organ for piano is to have the left hand take over the pedalboard notes, while sharing the two upper voices between the hands. I needed to rewrite and leave out notes to more or less maintain the texture. At times, the pianist “hangs on by a thread,” but in general I have tried my best to make it as idiomatic as possible.