Section II · Bach · Prelude and Fugue in D minor, BWV 875 · prelude
The whole prelude, 61 bars, line by line, with the questions an examiner asks about its form and its details. Look, answer out loud in English, then check.
Play from this score · big, page by page, for iPadThe notes were typed in from photographs of one edition (Henle), and drawn by computer. Every page was transcribed twice, independently, and every disagreement was settled against the photograph (zoomed in, and the position of each disputed note head measured against the staff lines). The first eight bars were read a third time, with every note head measured, because both readers said they had not measured them: the three readings agree on 123 of 124 notes and the one difference was settled on the photograph. The facts below about form, returns of music and the ending were found by searching the typed notes. Not exact: the ornament signs (bars 1, 2, 3, 6, 7 and 43 to 45, 50 are typed as mordents or trills; they may differ in detail), and some chords where several note heads touch (bars 36, 39, 52, 53, 57, 58, 60). Not typed in: fingering, most dynamics, and the editorial brackets. If anything here disagrees with your own score, your score is right.
The numbers under each line are the ones printed in the Henle edition (the small circled number at the start of each line). Another edition may number differently, so in the exam point to the music, or name the edition, before you say a number.
Press a part to see its bars lit up on the score below.
Each question sits under the line where its bars begin. Answer out loud first, then open the answer.
Before you play: what does the first page tell you about the piece, the time and the key?
The heading is PRAELUDIUM VI with BWV 875 at the right. The time signature is 3/4 and the key signature has one flat: D minor. Bar 1 starts with an eighth note (D5) and a run of sixteenth notes down the scale, over a left-hand D with a trill sign.
How is the prelude laid out? Are there repeat signs?
It has 61 bars in 3/4 and no repeat signs at all: the only special barline is the final one. It is a continuous perpetual-motion piece in two halves (continuous binary form): Part I is bars 1 to 25, going from D minor to a close on the dominant of A (E and G♯, bar 25); Part II starts at bar 26 and goes back to D minor; and the last six bars (56 to 61) are a short coda.
In 58 of the 61 bars a note starts on every sixteenth of the bar (the exceptions are bar 1, where the first note is an eighth, bar 30, and bar 61, which is one chord): that is the “perpetual motion”.
Look at bars 5 to 8 and compare them with bars 1 to 4. What has happened to the two hands?
The hands have exchanged their material (invertible counterpoint). The right-hand line of bars 2 to 4 comes back in the left hand in bars 6 to 8, exactly one octave lower: I compared them by computer and all 12 notes of each bar match, bar for bar. At the same time the left-hand notes of bars 2 and 3 are played by the right hand in bars 6 and 7, two octaves higher (4 of 4 notes in each bar).
So the exchange covers three bars (2 to 4 against 6 to 8), not four: bar 5 begins differently. The same exchange comes back in Part II: the left hand of bars 27 to 29 is the right hand of bars 2 to 4, five semitones lower.
Look at bars 18 to 21. What is unusual about the hands?
The left hand plays above the right hand: the hands cross. I found it by checking, bar by bar, whether a left-hand note sounds higher than a right-hand note at the same time: this happens in bars 18, 19, 20, 21, 23 and 25. The course notes explain the crossing as violin-style broken-chord figuration moved to the keyboard.
Look at bars 22 and 24. What are the very fast notes?
Each of these two bars starts with a short run of thirty-second notes (demisemiquavers), written as four quick notes before the sixteenths go on. They are the only thirty-second notes in the whole prelude (I searched every bar). The course notes say they belong to Bach's later revision of the piece; the score itself only shows that they are two short flourishes.
Where does Part II begin, and what does it do with the opening?
Bar 25, the last bar of Part I, has an E in the left hand and a G♯ in the right hand: the notes of the dominant of A (G♯ is the leading note). Part II starts at bar 26 in A minor.
It brings back the opening a fifth higher (D minor to A minor) with its two four-bar units in reverse order: bars 26 to 29 are bars 5 to 8 seven semitones higher, and bars 30 to 33 are bars 1 to 4 seven semitones higher (I compared the right-hand top line by computer: all 18 notes of 5 to 8 and all 47 notes of 1 to 4 match at the same beats and lengths).
Where are the lowest and the highest notes of the prelude?
The highest note is B♮5 (B natural, with the natural sign printed) in the right hand of bar 29. The lowest is C♯2 in the left hand of bar 49.
How does the prelude end? Where does the coda start?
In the last six bars, 56 to 61, the left hand starts every bar on D3: a tonic pedal, the “short coda over a held D” of the course notes. Bar 55 leads in with C♯ in the bass.
The last bar, 61, is a single chord held for the whole bar under a fermata, with the final barline: D3, F♯3, A3, D4. The third is F♯, not F: a D major chord at the end of a D minor piece, a tierce de Picardie.
The words to use are on the Answer Cards (Bach, Q3). To practise speaking, use the voice examiner and ask for Bach, question 3.