Organ concerto (Bach)

In his Weimar period Bach transcribed concertos by, among others, Antonio Vivaldi and Prince Johann Ernst of Saxe-Weimar for organ and for harpsichord.

Despite the fact that Carl Friedrich Zelter, director of the Sing-Akademie zu Berlin where many Bach manuscripts were held, had suggested Johann Sebastian as the author, the transcription was first published as a work by Wilhelm Friedemann in 1844 in the edition prepared for C.F.

The markings are also significant for what they show about performance practise at that time: during the course of a single piece, hands could switch manuals and organ stops could be changed.

On the organ Bach creates his own musical texture by exchanging the solo parts between hands and having the responding duet on a second manual.

For Williams (2003), Bach's redistribution of the constantly repeated quavers in the original is "no substitute for the lost rhetoric of the strings.

The dense chordal writing in the three introductory bars of the Grave is unusual and departs from Vivaldi's specification of "Adagio e spiccato".

Bach adapted the fugue to the organ as follows: the pedal does not play the bass line of the original allegro but has an accompanying role, rather than being a separate voice in the fugue; the writing does not distinguish between soloists and ripieno; parts are frequently redistributed; and extra semiquaver figures are introduced, particularly over the prolonged pedal point concluding the piece.

Bach used the same theme for the opening chorus of his cantata Ich hatte viel Bekümmernis, BWV 21, first performed on 17 June 1714, shortly before ill health forced Prince Johann Ernst to leave Weimar for treatment in Bad Schwalbach.

Although each return of the theme with its chromatic falling bass accompaniment is instantly recognizable, Bach's allotting of parts between the two manuals (Oberwerk and Rückpositiv) can occasionally obscure Vivaldi's sharp distinction between solo and ripieno players.

Towards the end of the piece, Bach fills out the accompaniment in the final virtuosic semiquaver solo episode by adding imitative quaver figures in the lower parts.