Pièce d'Orgue in G, BWV 572, also known as Fantasia in three parts, is written in a French style. It originated rather early in Bach's career (before 1712). The first part is entitled as Tres vitement (very fast), the second - Gravement (heavy) and the final part - Lentement (slow). Because of fast runs and passages, the opening and closing parts remind of a toccata, and the central solemn episode is written in a 5 part polyphonic texture.
The Italians would call the opening section the Passagio which was also a common feature in the North German Praeludia. However, it is questionable whether the Italian term is approprate in the French style composition. Basically it is a virtuosic episode written in a monophonic texture where we can find both the elements of arpeggio and scale-based passages. At any rate, even at this early stage of Bach's career, the composer shows a unique angle of blending multi-cultural elements in one work.
Pièce d'Orgue ends with a virtuosic but a little slower and heavier texture which have 5 voices encoded: 4 voices could be percieved in both hands and pompastic and magnificent Dominant pedal point in the pedal line.
I can't recall where these notes came from... ;-)
A few words about the performance: This is Bach alla English cathedral - full swell, swell box, etc.
It's also a bit sloppy. I just had Salisbury loaded, and this was laying there, so, I played it. Not the best, but hopefully fun to hear!