Composing a Fugue

The form of a fugue has the advantage of being somewhat strict, especially in its exposition. Thus, one can emulate fugue composition by following a few basic procedures, and then using the fugues of Bach as supreme (if somewhat intimidating!) examples.

Here is a straightfoward process for composing a fugue. To begin, we will write (and you will write) a three voice fugue with two repeating countersubjects. This fugue was created today for this page, by way of example.

1. Of course, you must create a subject. For a beginning fugue, it is best to keep it simple, and it is extremely helpful if you have a harmonic scheme in mind first before you create the subject. At very least, while you are creating the subject, you must hear a harmony in your imagination so that you are simulataneously creating a harmonic progression while creating the single-line melody. This is surely what Bach did; he would have instantly understood the harmonic implication of whatever subject he presented.

Here is a simple subject in G minor, expressing an unequivocal motion from tonic to dominant (i to V) in the first measure, and from dominant to tonic in the second measure. Your first fugue exposition assignment will ask you to write a subject according this precise harmonic sequence.

2. Now, decide which voice will state the subject  first (let's say that it's the alto voice) and then bring the second voice in at the dominant in another voice. We'll bring it in here in the soprano. Since this melody clearly expressed the tonic triad at the beginning, only moving to the dominant note at the end of the first measure, it's a safe bet that this can receive a real answer:

3. Next, we create a countersubject that helps define the harmony. We follow the traditional rules of counterpoint, which is to have primarily imperfect intervals on strong beats and to create contrary motion and contrasting rhythm between the two voices. Notice here that I choose an open fifth at the beginning of the fourth measure. This is in anticipation of a second countersubject, soon to be introduced, which will fill in the missing third. Since the C# was clearly stated on the previous two beats, the C# is kept in the ear even when the fifth becomes open.

4. The fourth stage is to leave a few blank measures on your working copy, which will shortly contain a modulatory passage. By skipping this modulation, you can go right on to create the final entrance of the subject, bringing in the countersubject transposed to the tonic, and introducing a second countersubject.  Here is the original subject, entering now in the bass voice, with the countersubject transposed up a fourth to the tonic, then up an octave to appear, quite brightly, in the soprano voice:

Note that this is the essence of what is known as invertible counterpoint. At the opening, the subject is on top and the countersubject is below. Here, the subject is down in the bass register while the countersubject is quite high in the soprano voice. And yet the two lines of counterpoint still complement each other in proper harmonic relationship, even though the two lines have been both transposed and inverted in relationship to each other.

5. Now we can create the second countersubject, which will first appear in the alto and will help to fill in that "missing harmony" in the second bar. For the second countersubject, you want to make something with rhythmic distinction, so that it acquires its own identify during the course of the fugue. We also have the task, in this example, of making sure we hit the F# on the downbeat of the second measure to fill in that empty fourth. Here is the countersubject:

And here is the the full entrance of the third voice:

There is a possible cross relation here between the E natural in the soprano and the Eb in the bass, but since the E natural is rising upwards, as if part of the G melodic minor scale, and the Eb is an upper neighbor of the D as part of the G natural minor scale, it sounds fine.

6. The last task, now that we see where the voices will be at the beginning of the third entrance, is to create the modulating link between the second and third entrances. First we lay the document out with a few missing measures...

...then we compose a piece of 2-part counterpoint that makes use of some of the rhythmic and melodic motives from the opening and performs a modulation back to the tonic key, preparing the way for the entrance of the third voice. It turns out when I set out to write it, it took three measures to make the transition. I wanted a sequence, so I continued the line of the end of the melody and first had it modulate back to G minor. Then I thought, why not?, how about continuing the sequence and touch briefly on F major, the dominant of the relative major. After this two-measure sequence, an additional measure was needed to prepare the final entrance.

There you have it. As long you as you create a harmonically simple subject for your first fugue attempt, you can pretty readily create a fugue exposition that sounds a little bit like Bach!

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