Nun ist das Heil und die Kraft, Bach-Werke-Verzeichnis|50, is a choral movement long attributed to Johann Sebastian Bach and assumed to be part of a lost cantata. The work was likely composed in 1723 but the date of its first performance is unknown.
History and text
American Bach scholar William H. Scheide suggested that the work was written for a Michaelmascelebration. However, the exact dates of composition and first performance are unknown. The work has fascinated Bach scholars because of questions about its provenance. No autograph sources exist, and the earliest copies extant do not mention Bach's name. In 1982, Scheide argued that the existing version is an arrangement by an unknown hand of a lost original for five voices by J. S. Bach. His argument was based on irregularities in BWV 50's part-writing, which are highly unlike the writing of Bach. In 2000, the American performer and scholar Joshua Rifkin argued that a more plausible solution of this puzzle is that the author of BWV 50 was not Bach at all, but an unknown composer of the era. The suggestion is controversial. The prescribed readings for the day were from and ; this movement draws from Revelation 12:10. Its text is "Nun ist das Heil und die Kraft und das Reich und die Macht unsers Gottes seines Christus worden, weil der verworfen ist, der sie verklagete Tag und Nacht vor Gott".
Scoring
The piece is written for an unusually large orchestra. The score involves two four-part choirs, three trumpets, timpani, three oboes, two violins, viola, and basso continuo. The movement is a chorus, or "coro doppio".
Music
Like other cantatas for Michaelmas, it features texture layering from the lowest range to the highest, and a contrapuntalrepresentation of "battles and massing armies". It is in two distinct sections and uses fugal techniques. The movement begins with a "strong declaration in unharmonized octaves", pairing the low strings with the bass voice of the first choir. A rhythmic shift creates a "floating, turn-around feeling" before the tenor line enters, followed by alto and soprano. As this choir shifts into rhythmic counterpoint, the second choir, trumpet, and oboes enter. The movement also incorporates call-and-response, military-like tattoos, and an inversion of the previous order of thematic entry. The final twelve bars adopt a chromatic style not heard earlier in the piece.
Recordings
Berliner Philharmonischer Chor / Berliner Philharmoniker, Carl Schuricht. J. S. Bach: Motet, Singet dem Herrn; Cantata No. 50; Cantata No. 104. Telefunken, 1934/8.
