Prelude Analysis, BWV 998 by J.S. Bach

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The Prelude from J.S. Bach's Prelude, Fugue and Allegro, BWV 998 has always interested me. Actually everything Bach has ever written has always interested me. But since I have only one lifetime (so I think) I will have to select a few of his works for study and this one I think is especially beautiful.

I have set up the analysis using two staves, the upper containing the actual music along with the harmonic analysis using chord symbols and Roman numerals and the lower staff showing the reduction in a way similar to what Heinrich Schenker (1868-1935) would do.  As I have said before, Schenker is a strong influence on my analytical technique.

I hope most of the analysis is self explanatory with the use of the pdf file above. I would like to take a closer look at some of the most interesting features.

The most prominent and ingenious feature of this piece can be seen in the reduction staff. Almost the entire piece can be seen and heard as a series of ascending and descending step-wise lines in the soprano and bass. Notice the long step-wise descending line in the upper voice which begins on the high D in measure one and descends (with two, one octave displacements in measures eleven and nineteen) to the B in measure twenty-seven. The bass support for this line is usually a tenth, sometimes a sixth, which descends step-wise right along with it after the pedal point breaks in measure four.

Once the B is reached (third of subdominant) in measure twenty-seven we have a short ascending line moving from the B to the F# in measure thirty (third of tonic) forming another tenth with the bass. This begins the next descent from F# down to C# in measure thirty-three with bass support a tenth below.

An arpeggiation to the high A begins the next descent back to the F# in measure thirty-six. This time the bass ascends step-wise in contrary motion with the soprano voice.

Once this is reached an ascending step-wise line occurs in the soprano along with a descending step-wise line in the bass, taking us to the G and Bb in measure thirty-eight (minor subdominant, a high point harmonically).

After the Bb descends as it should to the A in measure forty, the final step-wise descent begins, taking us from the high A in measure forty all the way down to the final tonic D at the close of the piece (again with octave displacements occurring in measures forty-two and forty-six). The bass this time is a tonic (D) pedal point beginning in measure forty-two through the first half of forty-six with the traditional cadential 4-5-1 bass line occurring at the close.

If possible, play the reduction staff along with a recording of this prelude and you will hear the underlying voice-leading clearly. With a bit of experience this reduction method developed by Schenker will allow you to see and hear this deeper structure which seems to exist in all music by the great composers of the tonal era. For further study please read Introduction to Schenkerian Analysis by Allen Forte and Steven E. Gilbert, W.W. Norton and Company, New York, NY.

The harmonic plan is also quite interesting and a bit unusual. Notice how all closely related keys are touched on in the course of this prelude.

Beginning with tonic (D major) we move into the dominant (A major), then the supertonic (E minor), then the submediant (B minor), the mediant (F# minor) before returning to tonic in measure twenty-three. Notice how these key areas are arranged in descending fourths rather than the more common descending fifths.

We finally get the subdominant key area (G major, measure twenty-four) before the final return to the tonic key in measure twenty-eight in which we stay to the end. This final section contains a most striking harmonic feature, namely the minor subdominant (Gm) in measure thirty-seven and thirty-eight which morphs into an even more striking Neapolitan Sixth chord (Eb/G) in measure thirty-nine.

Then, as if that isn't enough, Bach resolves this Neapolitan Sixth chord in a most unusual way. Rather than moving directly to the dominant (A) he first moves to the V/V (E7) in third inversion with this great appoggiatura in the upper voice on beat one of measure forty. You can see how the two active notes (Bb and Eb) resolve up by half-step to the B-natural and E-natural and the G moves first to A and then resolves to G# to form the V/V.  Then of course we finally get the dominant (A7) in the same measure. That is what I call cosmic!

Note: This may be helpful in understanding the function of the Neapolitan Sixth chord. Think of it as a variation of the minor subdominant (iv) chord. Raising the fifth of the minor iv chord one half-step as Bach does will form the Neapolitan Sixth chord. In the key of D major the minor (borrowed) iv chord (G-Bb-D) becomes the Neapolitan Sixth chord by raising the D to Eb (G-Bb-Eb). The Neapolitan Sixth usually prepares or precedes the dominant. This is the reason it is usually in first inversion. The fourth scale degree is in the bass which then moves up to the fifth scale degree (dominant) while the other voices resolve in contrary motion.

This sets up a restatement of the opening two measures beginning in measure forty-two before the final wrap up in the tonic key.

One more note: The m7b5 chord is known more commonly in classical analysis as a half-diminished seventh chord. I prefer to use m7b5 as it is more descriptive of this chord type.

I always find the most interesting  and surprising things in Bach's music. I hope you will too. Enjoy this one!

10 comments

  • Charlie
    Charlie
    Hey John, Thank you for sharing your work. I could spend a couple of hours going through your analysis but I am sooo damn lazy. I'd rather play it. I like the Schenkerian reduction. I'll have to learn more about his work. For what instrument was this prelude originally written? Cello? Clavicord?

    Hey John, Thank you for sharing your work. I could spend a couple of hours going through your analysis but I am sooo damn lazy. I'd rather play it. I like the Schenkerian reduction. I'll have to learn more about his work.

    For what instrument was this prelude originally written? Cello? Clavicord?

  • Alphonsus Jr.
    Alphonsus Jr.
    Additionally, as my teacher pointed out, the structure of the piece might be broken down as follows: T3D - E2 - T3A - E5 - T3b - E8 - T3G - E10 - Climax/Cadenza4 - Coda7 Where: T = Theme E = Episode Numbers = span of measures involved D, A, b, G = keys One might also note the Fibonacci Series embedded in this piece: E2 + T3A ----> E5, then E5 + T3b ----> E8, then E8 + T3G ---> 11 measures of the combo of the Climax/Cadenza plus the Coda (with E10 between T3G and these last 11 measures as a clever trick).

    Additionally, as my teacher pointed out, the structure of the piece might be broken down as follows:

    T3D - E2 - T3A - E5 - T3b - E8 - T3G - E10 - Climax/Cadenza4 - Coda7

    Where:
    T = Theme
    E = Episode
    Numbers = span of measures involved
    D, A, b, G = keys

    One might also note the Fibonacci Series embedded in this piece: E2 + T3A ----> E5, then E5 + T3b ----> E8, then E8 + T3G ---> 11 measures of the combo of the Climax/Cadenza plus the Coda (with E10 between T3G and these last 11 measures as a clever trick).

  • Steve Bornfeld
    Steve Bornfeld
    Charlie-- You know the question of what Bach works were originally intended for lute is pretty controversial. Usually PFA is considered to be a lute work; but my understanding is that the original manuscript was listed as for "lautenwerke" which is a gut-strung keyboard instrument. Somewhere I have a recording allegedly played on a copy of such an instrument; some of the pieces sound like lute; some sound like harpsichord.

    Charlie--

    You know the question of what Bach works were originally intended for lute is pretty controversial. Usually PFA is considered to be a lute work; but my understanding is that the original manuscript was listed as for "lautenwerke" which is a gut-strung keyboard instrument. Somewhere I have a recording allegedly played on a copy of such an instrument; some of the pieces sound like lute; some sound like harpsichord.

  • Jim Thompson
    Jim Thompson
    Thanks for the analysis. Enjoyed reading it. This has long been one of my favorites. A story... I first heard this mid 70s from a Bream LP. I could not find the printed score so being a good music student I took dictation from the record. After I filled up a page, sat down to study and figure out the guitar fingerings. Was only later that I learned that I got a couple notes wrong. Sorry, now the right ones sound wrong to me! But seriously, when I read Alphonsus Jr. note about Fibonacci, I thought, "No wonder this sounds so magical!"

    Thanks for the analysis. Enjoyed reading it. This has long been one of my favorites. A story...

    I first heard this mid 70s from a Bream LP. I could not find the printed score so being a good music student I took dictation from the record. After I filled up a page, sat down to study and figure out the guitar fingerings.

    Was only later that I learned that I got a couple notes wrong. Sorry, now the right ones sound wrong to me!

    But seriously, when I read Alphonsus Jr. note about Fibonacci, I thought, "No wonder this sounds so magical!"

  • Jack from Taiwan
    Jack from Taiwan
    Very nice chord analysis! It helps me a lot to understand the whole piece!

    Very nice chord analysis! It helps me a lot to understand the whole piece!

  • Robbie
    Robbie
    Hi John, Thank you for putting up this blog. Your analyses are very important and helpful to the learning musician. Although I got most of the information I needed from your writings, I feel I need to pay the affordable price of $1.00 to let you know that I used your analysis. If time permits, please put up more analysis of guitar pieces. Do you have any interest in Frank Martin's Quatre pièces brèves? If not for being a starving student, I would provide a greater restitution. Thanks John. -Robbie

    Hi John,

    Thank you for putting up this blog. Your analyses are very important and helpful to the learning musician. Although I got most of the information I needed from your writings, I feel I need to pay the affordable price of $1.00 to let you know that I used your analysis.

    If time permits, please put up more analysis of guitar pieces. Do you have any interest in Frank Martin's Quatre pièces brèves?

    If not for being a starving student, I would provide a greater restitution.

    Thanks John.

    -Robbie

  • Nigel Jones
    Nigel Jones
    Hi John, Thanks for sending through the .pdf analysis. Really enjoy reading your blog which I have found to be very helpful. All the best and look forward to your thoughts on the Fugue ! Cheers

    Hi John,
    Thanks for sending through the .pdf analysis. Really enjoy reading your blog which I have found to be very helpful. All the best and look forward to your thoughts on the Fugue ! Cheers

  • Ben Salfield
    Ben Salfield
    The Prelude, Fugue and Allegro BWV 998 were originally written "for lute or harpsichord" according to the title.

    The Prelude, Fugue and Allegro BWV 998 were originally written "for lute or harpsichord" according to the title.

  • MIA0007
    MIA0007
    Loveyour work! How about analysing the Little Prelude in Cminor 999 by Bach? Ending in a G chord is hard for me to understand.

    Loveyour work! How about analysing the Little Prelude in Cminor 999 by Bach? Ending in a G chord is hard for me to understand.

  • Elliot
    Elliot
    Thanks so much for analyzing this ingenious and wonderful piece. This piece is lovely

    Thanks so much for analyzing this ingenious and wonderful piece.

    This piece is lovely

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