This historic recording is one of three improvisations recorded in 1928 with Louis Vierne at the keys of the 1868 Cavaille-Coll Grand Organ in the magnificent acoustics of the Cathedral of Notre Dame de Paris [See menu bar, Slide Shows, Slide Show 11 subpage].

When this recording was made this instrument was in abominable shape, much of it wasn't working, most of the rest was hideously out of tune, and sound recording technology of the time was primitive compared with that of today.  Still, Vierne by then was known the world over not only as a virtuoso organist, composer of genius, and beloved teacher, but also a brilliant improvisor, as this recording shows.

First published in 1929-1930, these improvisations were first transcribed to paper from the original recordings in 1954 by Vierne's pupil Maurice Durufle.  Playback equipment back then did not provide the best fidelity, and Durufle's reconstruction of this work, entitled Marche episcopale, while admirable and accurate for the time, was found in later years to have errors.

More recently in 2015 this music was retranscribed by organist Danijel Drilo using modern high-tech playback, and this version of the reconstructed score appears in this video.

Anyone familiar with the 6-part form Vierne taught his students for improvising on a single free theme will easily discern the form it takes, which in this case stretches to 76 bars.

Treated homophonically, the theme is first announced in the home key with the full organ and is composed of four modulating phrases of 4 bars each, the last of which is irregular and spliced at measure 16 with an additional 4-bar phrase.

The music then proceeds without a bridge and restatement of the theme directly into a development of 30 bars based upon the first 2 notes of the theme in the relative key.  The hands move to an expressive manual for this development during which the pedal is silent and the overall volume is reduced.  

Preceded by a trill in the right hand, an 8-bar long preparation for reentry begins without pause on measure 50 after which the theme reenters in the home key once again with the full organ and resumption of the pedal line.  After wandering chromatically through 16 more bars the improvisation is rounded off with a short 3-bar coda employing a 4-3 suspension ("amen" ending).

Thus Vierne employs in this improvisation his 6-part form save for the bridge and restatement of the theme, all the while demonstrating this instrument's fire and powers of dynamic nuance just as much as his imagination.

Much of what we find in this music -- lyrical melody, irregular phrase length, unexpected modulations to distant keys, strict adherence to form -- all were characteristic of Vierne.  Think of what it took to be able to improvise something this majestic and well-crafted, on the spot.