1. Subject. Take a look at the theme at the beginning of the piece. It is 4 measures long. Notice how it consists both of the chordal tones of the d minor key and the notes in stepwise motion.
2. Answer. The answer is the second subject entrance after the theme. Usually it is in the key of the dominant. Look at it and discover if the answer is a perfect transposition of the subject (real answer) or it has some melodic modifications (tonal answer) so that it would stay in the same mode.
3. Countersubject. A countersubject is a contrasting melody which goes together with the answer. The countersubject is written in a voice which previously had a subject. Check if the countersubject stays the same throughout the piece or if it changes every time there is a subject.
4. Exposition. Exposition consists of the subject and answer series until every voice has entered. Since this fugue is in 4 parts, the exposition also lasts until all voices have finished their entrances, usually in alternation of the key of the tonic and dominant.
5. Counter-exposition. After the exposition, several other entrances form the counter-exposition. The tonal design for it might vary a little but the generally the order of entrances are inverted - answer comes before the subject.
6. Episodes. The episodes are parts of the fugue that connect different subject entries. Usually they are formed of sequences based on the material from the subject or countersubject. Look for episodes between the exposition and counter-exposition. Additionally, there are episodes after the counter-exposition.
7. Other subject entrances. Most of the time other subject entrances move to closely related keys. However, since it is a simple fugue, the subjects continue to be in the tonic and in the dominant.
8. Pedal points. Towards the end of the fugue, there are 2 episodes which are built around two sustained notes in the bass part. The first is in the key of the dominant and the second is built around the tonic note. The dominant pedal point increases tension and features constant fluctuation between the key of the dominant and the tonic. The tonic pedal point is like a resolution of this tension - there is a constant alternation between the key of the tonic and subdominant.
Many fugues also have canonic subject or answer entrances towards the end of the composition. This part is called a stretto. However, since this is only the first in the series of complex fugues in the cycle of the Art of the Fugue, there are no canonic subject entrances in this fugue.
Use the above steps in analyzing the Contrapunctus No. 1 from the Art of the Fugue by Bach today. After you know how the piece is put together, you can write in fingering and pedaling and start practicing it.
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