Bach - The Well-Tempered Clavier, Book I, Nos. 7-12

The etudes of Chopin and other piano composers of the 19th century owe a great deal to J.S. Bach, for the 48 preludes and fugues of The Well Tempered Clavier are in many ways models for them. Bach's works are not only meant to instruct (as are etudes in the broadest sense of the term, usually by highlighting a specific area of keyboard technique) but to give enjoyment to the player.  Bach said as much himself on the title page of The Well Tempered Clavier Book I:

...for the profit and use of musical youth desirous of learning, and especially for the pastime of those already skilled in this study.

Many of the preludes of The Well Tempered Clavier are forerunners of the etudes of a later era, while the fugues are etudes of a specific kind themselves. No wonder that Chopin used Bach's music as a constant inspiration for composing as well as for warming up his hands (and mind) before playing the piano. 

Prelude and Fugue No. 7 in E-flat major BWV 852 -  The custom of pairing a prelude with a fugue began many years before Bach was active. The playing of an improvised prelude was twofold; to give the performer a chance to warm up his fingers and to set the home key of the fugue that was to come. Bach took this prelude playing tradition and enriched it. Prelude No. 7 of Book One is an excellent example of this, as it breaks the boundaries of tradition with a three-part form that includes a prelude, short fugue and a longer fugue.  The first section is in true prelude fashion and runs for ten measures:

This short section ends with a flourish and leads directly to the second section which consists of a short motive that is treated contrapuntally with numerous entrances until it dissolves into the third section, which is considered a fugue in itself.

Th 3-voice fugue proper is based on a short, perky two-measure subject that begins, circles around and ends on B-flat, the dominant of E-flat major, but the chord outlined in the figuration is E-flat major.:

The next two measures has the subject revolve around the note E-flat, which is the dominant note of A-flat major, which is in actuality the chord that the figuration outlines. Most of the material in this fugue is in keys closely related to the home key of E-flat, including  a short entry of the subject in C minor, the relative minor of the home key. The fugue ends with chromaticism and cadence.

Prelude In E-flat Minor, Fugue In D-sharp Minor No. 8 BWV 853 - Bach uses this prelude and fugue to show how the well-tempered keyboard can play in tune in keys containing many sharps or flats, something that was not possible with most other tunings. The prelude is in E-flat minor, a key that contains six flats:

The prelude begins with a bare E-flat minor triad. With rolled chords and modulations to B-flat minor and A-flat minor occur, and Bach's use of differing rhythms give this prelude a mood of reflection instead of sorrow. The mood brightens as the prelude ends in E-flat major.

The 3-voiced fugue is in D-sharp minor, a key with six sharps. The subject is about two and a half measures long, and it is truly the subject of this fugue as there is hardly much else going on besides the presentation and rehearing of the subject. Bach does create variety by varying the subject by inversion, augmentation and slight changes of rhythm.  

Prelude and Fugue No. 9 In E Major BWV 854 - The prelude is in a light polyphonic style and is short at only 24 measures:

After the opening section is played out, there is a central section of a slightly different character. The opening section returns and a short ending rounds out a prelude that has been described as pastoral.

The 3-voiced fugue has a terse subject of only a measure and a half in length:

Within a short span of time, Bach manages to state the subject many times and includes numerous episodes that do not contain the subject. This fugue creates a whirlwind effect that can be realized without playing it at an overly fast tempo.

Prelude and Fugue No. 10 In E Minor BWV 855 - This prelude is a reworking of a shorter prelude in the same key from The Notebook For Wilhelm Friedmann, a set of pieces for Bach's eldest son. It is in two parts, with the first part being an ornamented melody in the right hand accompanied by sixteenth notes in the left.

 This continues until roughly at the half way point the tempo increases to presto and the right hand changes to running sixteenth notes along with the left hand:

This presto section recalls a somewhat similar texture contained in the Prelude No. 2 In C Minor of Book I. The prelude continues in this way until the ending cadence in E major.

A rare example of a 2-voiced fugue, it begins with a subject that consists of two bars of running, chromatic sixteenth notes and ends with two eighth notes:

The nature of the subject and the two-voice structure hints that this needs to be played at a brisk tempo. The end of this fugue happen s quite suddenly, and is in E major.

Prelude and Fugue No. 11 In F Major BWV 856 - In the style of a two part invention, the opening parts for each hand reverse throughout this short prelude:

The 3-voiced fugue moves at a steady, somewhat rapid pace as the regular rhythmic pattern  of the subject makes it easy to follow with its many entrances.

Prelude and Fugue No. 12 In F Minor BWV 857 - The musical interpretation of Bach's music can be a problem, or an opportunity, as one sees things. This prelude is a case in point:

The quarter notes held in the right hand can be thought of as a melody and the sixteenth notes of the right hand an accompaniment, or the reverse can be done. and the bass notes can also be brought out as an integral part of the melodic content. Such are just a few of the possibilities within Bach's music. Whichever interpretation is decided upon will dictate the tempo of this prelude to a large extent.

The 4-voice fugue has subject of three measures:

The irregularity of a three-measure subject is glossed over somewhat by the answer of the subject in a much different rhythm of eighth and sixteenth notes. This makes the subject appear to be an ethereally slow one that gives a clue to the proper tempo of the fugue overall. This is the halfway point of Book I, and gives credence to the thought that Bach wrote the work as progressing in difficulty. Compare this prelude and fugue to the first one in C major, and it seems obvious. This fugue is complex, with different counter subjects and episodes with the subject and its slow pace weaving in and out of the musical texture.