My last lesson for www.organimprovisation.com featured instructions on transposition and suggested using a piece by Louis Vierne as the transposition exercise and a model for improvising. The piece is a relatively simple piece from the 24 Pièces en style libre: 1. Préambule.
As transposition practice, I played it in C# major, D Major, Eb Major, and started it in several other keys.
After that, I followed the score as a model and improvised some imitation Vierne in F Major and in G minor. There are some hesitations as I searched for similar interesting tonal gestures without following exactly what Vierne did, but that’s why we practice. I decided to make this exercise my prelude this weekend, so there are two more that follow the score less slavishly in A minor and D minor as well.