Now is [come] salvation and strength in D major, BWV 50

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 (for double choir) 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 (but highly gifted) composer of the era. The suggestion is controversial.