The early version of the prelude (ca.1738) is found in Go.S.19
only. It explores less expressive potential .
There are two further preludes which may be mentioned here: they were
previously paired with the early version of the accompanying fugue (BWV
BWV 902a (ca.1720): the earlier one transmitted to Kellner's
MS P 804 alone. Written in 3/4 metre in 33 bars, this is a
closer match to BWV 902/2 both motifically and stylistically .
BWV 902/1 (ca.1730): the later one commonly found in the early
sources such as P 1089, replacing BWV 902a. It is a substantial
binary piece (in quasi-sonata form). Stylistically it is more mature (4/4
metre in 56 bars with repeats) than the version found in P 804.
There is a slightly revised version reflected in N.Mus.ms.10490.
Final Version (1739)
No autograph survives. The 'London autograph' is a copy made by Anna
Magdalena. There are no significant differences between two manuscript