Bach’s authorship of this piece is uncertain, hence its catalogisation in Anhang II of Schmieder’s Bachwerke Verzeichnis. Two sources for this piece are available online. Though it’s clearly the same piece, both sources differ in lots of details. The one from manuscript Mus. Hs. 35149, available at the Östereichische Nationalbibliothek seems to me the older version, perhaps even the ‘original’. The version available at the Bach Archiv Leipzig (D-LEb Rara Ib, 45) is a more embellished version. It is like someone wrote out how an experienced player could spontaneously add al sorts of details while playing the simple version from Mus. Hs. 35149.
I think it fits the tradition of organ playing in those days: a composition was more like an invitation to improvise, than meant to be played exactly as written.
Though Bach’s authorship is uncertain, it is nevertheless an elegantly constructed piece. The first phrase of the choral melody is first the basis of a four voice fugue. After that the choral melody is played in the pedal, accompanied by fast moving figures in the hand. Each phrase of the choral melody is foreshadowed in the soprano voice. All in all a fitting piece for the day, in both versions. Happy Easter!
HW: Prestant 8′, Octaaf 4′, Quintfluit 3′, Octaaf 2′, Mixtuur
Ped: Octaaf 8′, Octaaf 4′, Trompet 8′
Score available here: http://partitura.org/index.php/bach-christ-ist-erstanden-bwv-anh-ii-51-version-mus-hs-35149/