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b. 5

composition: Op. 28 No. 14, Prelude in E♭ minor

c-c1 w A, literal reading (→FE,FCGE1)

c-c1 in EE, GE2 (→GE3) & FES

..

The missing naturals raising c-c1 to c-c1 are almost certainly Chopin's mistake. It is indicated by the naturals added by Chopin in FES as well as by the cautionary  written in A before c1 in the next bar (eventually crossed out), which suggests that Chopin assumed that it was c that was valid there*.
The naturals were added in EE and GE2 (→GE3).


* A precautionary approach should be taken in the case of a reasoning based on a cautionary accidental – in b. 12 in A we can also observe crossed-out flats before c-c1, although the sound of those notes had already been consolidated at the beginning of b. 10 (Chopin was not always certain which accidentals were included in the key signature).

category imprint: Interpretations within context; Differences between sources; Source & stylistic information

issues: Annotations in teaching copies , EE revisions , GE revisions , Omission of current key accidentals , Deletions in A , Annotations in FES , Last key signature sign

b. 5

composition: Op. 28 No. 12, Prelude in G♯ minor

..

In the main text we add a cautionary  before c2.

category imprint: Editorial revisions

b. 5-7

composition: Op. 28 No. 18, Prelude in F minor

..

In A one can see that in b. 5 Chopin initially wanted to lead the L.H. semiquaver sequence to the middle of the bar. He also introduced a similar change into b. 7, in which he started writing L.H. semiquavers from the beginning of the bar.

category imprint: Corrections & alterations; Source & stylistic information

issues: Corrections in A , Deletions in A

b. 5

composition: Op. 28 No. 17, Prelude in A♭ major

g2 in FCI & A (→FC,FEEE)

f2 in GE1

g2 with  in GE2 (→GE3)

..

The version of GE1 featuring f2 on the 3rd quaver is most probably a mistake of the engraver. In GE2 f2 was rightly changed to g2; at the same time, a cautionary  was added before the latter. We include this addition, which we find justified, in the main text.

category imprint: Differences between sources; Editorial revisions

issues: Errors in GE , GE revisions

b. 5

composition: Op. 28 No. 17, Prelude in A♭ major

Triads in FCI & A (→FC,FEEE)

Thirds in GE

..

The missing a notes in the chords in the 2nd half of the bar are a mistake of the engraver of GE.

category imprint: Differences between sources

issues: Errors in GE