Quinquagésime

I became aware of this piece through a performance by Agnus_Dei on 02/13/21. I liked it a lot and so I learned it for the next service in church.
Further information on the composer and the Gregorian origin of the piece can be found in the contribution by Agnus_Dei.
Benoit lived in France and played Cavaillé-Coll organs himself, so I used the Caen sample set.