Prelude in F Major, BWV 856
OK, so why is this green? If the connections between music and color can be traced back through Newton to the Ancient Greeks, how does that make this particular Prelude green? Well, just listen to it.
This is as close as Bach gets to program music in the Well Tempered Klavier. You can hear the birds twittering in the skies, leaping from trill to trill, sometimes ducking under a bough to trill in the middle voice, soughing in the bass:
The bass has a comically ponderous sequence (at 0'20") that sounds just like a water mill, churning away below the ledger lines. The text is watery - 12/8, with 6 notes to a beat, played as fluidly as you can. If that doesn't suggest Spring to you, then you need to listen to more Vivaldi.
At no point in this lovely little piece do the semiquavers (sixteenth notes) ever stop. The final arpeggio just rolls out of sight, a stream merrily cascading away. It's not for nothing that Bach's name means river:
This was the first one I ever learned in the book, new to America in 1975. It's the shortest one in the set, beating the Prelude in E Major by 5 seconds. Back then, it sounded like a fresh start. Here in Tampere, it still sounds like a new beginning. It always does, no matter how many times you hear it. If the ending doesn't make you laugh, nothing will. And that is what makes it green: it will always be new, always be innocent, always be Bach.
Prelude in F Major, BWV 856, measure 18
Trills High and Low (measures 9-10 and 13-14)