With it's forty-five chorale preludes, the Orgelbuchlein bears witness to a mastery of the art of improvisation on the organ, as the congregation heard it at the time before singing the hymn in it's turn. It was a tempting experiment to revive this primary function: by collaborating with the combined forces of the Ensemble Vocal Bergamasque and the Maitrise de Notre-Dame de Paris, Benjamin Alard gives the 'little organ book' it's full significance and expressive power.