It's the chief danger faced by the composer when writing any organ music, particularly a longer work built upon a cantus firmus (c.f.), or fixed melody, such as a set of variations; this becomes especially acute when the plan for the composition makes it non-modulating through the majority of the variations.
We can avoid this chief danger by doing what's interesting or unexpected, perhaps even daring, with each variation.
Someone doesn't necessarily need to hold a certificate or advanced degree from a recognized college or conservatory of music to write something compelling like this.
They don't have to have spent part their life earning their living as a musician.
They just need to know the basics about harmony, counterpoint, notation, scales and chords, how the Circle works, what to avoid, and to be patient, doggedly determined, and have the guts to try.
It will help to download and print a hard of the C Major Op. 4 Variations on a cantus firmus (photo) and follow it with this narrative about how it was put together.
If we start with a hymn-like theme, let's say, a c.f. 16 bars long made up of 4 phrases of equal length, we might consider writing a fanfare-like introduction using the melodic outline of the first 2 phrases of the theme in rhythmic transformation (same pitches in sequence but different note values); this would get the work off to an impressive start as it provides a strong sense of unity between the introduction and the first statement of the theme.
If we begin our theme in a 4 voice texture, why not introduce it with something unexpected in the rhythm of the other voices from the get-go, such as triplets in the accompaniment; the listener finds something like this unexpected and arresting to the ear.
For the 1st variation we might try working the c.f. as a 2 voice canon at the octave with the right hand following one measure behind the left hand in a 4 voice texture.
The listener won't expect this right off the bat, to start a big work like this with a strict 2 voice canon.
A famous example of this is Bach's organ Toccata in F Major, where he starts it, most unexpectedly, with an extended strict 2 voice canon at the octave in the hands over a held pedal note; no one would expect the opening of an organ toccata to begin with a learned (pronounced "ler'-ned) device like this, and it works amazingly well in the hands of this master of masters.
By stirring the sands of monotony this way, Bach succeeded in separating this work from the common and created something interesting, uncommon, and ultimately a permanent contribution to the organ repertoire [ See blog, Do The Unexpected ].
There's a lesson in this.
No one will expect the 2nd variation to repeat this procedure in 4 part texture, only this time switching out the parts in another 2 voice canon at the octave so the left hand this time is following the right.
That's exactly why we should do it.
For the 3rd variation we might consider restricting the c.f. to the tenor and bass lines but keep it moving between them, reducing the texture to 3 parts.
It's okay to dilute the formal rigor of which voice carries the c.f. here, as long as the result is smooth and pleasing to the ear.
We might then continue this 3 part texture for the next variation, switching the theme to the top line, starting it there, then sending it to the tenor or bass voice for every other measure.
Next, we might reduce the texture down to 2 voices and make the theme disappear in figuration which suggests a harmony, forcing the listener's ear to search for it amidst a series of ascending arpeggios spread across both staves.
Following this, we might reintroduce a 3 voice texture using a series of descending scalar passages interplaying with a simple bass motive consisting of an octave leap downward, still making the c.f. disappear in figuration.
For the next (7th) variation we might have the c.f. return in the top line, and work it against a short, rhythmic motive reappearing in the bass on the even numbered measures.
For the 8th variation we might continue this procedure in 3 part texture, this time having the same bass motive appear only in the odd numbered measures.
For the next (9th) variation we might create another bass motive moving in a dotted rhythm, have it appear on the even numbered measures, and employ ascending arpeggios divided between the 2 hands on the odd numbered measures, working it this time in a more dense 4 voice texture.
We're already up to 9 variations here, and it seems like we've barely gotten started ...
For the 10th variation we might reduce the texture down to 3 voices again and try something really bold ... like introducing the c.f. in inverse movement in the left hand, in another 2 voice canon at the octave, only with the c.f. entering right side up, in the right hand, if it will work.
This unusual procedure of juxtaposing a c.f. with itself in inverse movement in a 2 voice canon at the octave (provided it works and makes agreeable harmony) is a tricky business; we have to decide on a place for the 3rd free voice when the other 2 lines moving in canonic imitation happen to be very close together, are stationary, are moving in similar motion, or sounding octaves.
We're free here, to put the 3rd free voice either in the alto or bass and gradually nudge it along this way, our choice.
We may also find it necessary to exercise some discretion here [See blog, Poetic License] and tweak one note in the upside down version, as it is here, to get it to sound consonant with the right hand.
In addition, when the canon is between the soprano follower (right side up) in the right hand and the tenor leader (in inverse) in the left hand, and the inverse enters the alto range, it will need to be divided between the alto and tenor voices.
In situations like this the tenor will take over playing a free voice for a few beats in those places until the inverse c.f. can return again to the tenor range.
Again, it's perfectly all right to dilute the formal rigor here as long as the result is smooth and pleasing to the ear, which is our guide for everything; if we can get it to work at all, it's a signal achievement.
It's in fact advantageous to take these kinds of liberties because it's another means of varying how we're presenting the c.f., which is the whole purpose of writing or improvising variations; there's no shame in being bold like this [See blog, Getting Started With Writing, Part VI].
Having introduced the c.f. in inverse movement this way, you might then, for the next (11th) variation bring it more to the fore by moving it to the top voice and introducing it against running notes in the left hand.
You might quicken the tempo slightly here, start it in 2 voices, then add the 3rd voice a few measures later, as the momentum builds.
Here the c.f. might also be separated into halves, with the 1st half harmonized in the home key (C Major) and the 2nd half shifting to the parallel minor, i.e., c minor.
A short transition based upon the first 3 notes of the c.f. might then be inserted here to prepare the way for the next (12th) variation.
Now to really stir the sands of monotony that will set this work apart from the common, we can making the 12th variation into a 4 voice fugato by quickening the tempo and using the upside down version of just the 1st phrase of the c.f. as a (1st) countersubject to a new companion subject in faster notes made to blend with it and serve as its rhythmic complement.
This fugato variation would then proceed as with a standard 4 voice fugue exposition with entries alternating between the home key and the dominant (I-V-I-V) and then perhaps continue through a series of additional entries until everything comes to an unexpected, complete stop on, let's say, a 1st inversion Neopolitan triad (the so-called "Neopolitan 6th chord" -- a major triad constructed on the lowered 2nd scale degree).
In such a scheme, since the inverted c.f. (1st countersubject) would begin on the 1st scale degree (the note C), the companion subject might properly begin on the 3rd scale degree (the note E) with the answer coming in the dominant key (G Major) on the 7th scale degree (the note B).
With the 3rd and 4th entries in the exposition 2 more counterpoints will be added which, if maintained throughout, would take on the function of 2nd and 3rd countersubjects thus creating a fugato variation proceeding in very lively quadruple counterpoint
In taking a "stab" at this type of variation, it seems very appropriate for the 4 voices to enter in the order of soprano, tenor, alto, bass ... or S-T-A-B.
Having the opening voice in the top line will also help to keep the energy level from dropping when the texture reduces down from the 11th variation to only one moving line.
The common practice way of constructing this fugato exposition would be to have the (1st) countersubject (inverted c.f.) appearing on the heels of the companion subject successively in each voice with each entry ... with the 2nd countersubject, in its turn, appearing on the heels of the 1st countersubject in each successive entry (and the 3rd countersubject, in its turn, appearing on the heels of the 2nd countersubject in each successive entry).
Since this fugato should sound like it belongs to a set of variations and not a departure into a full blown fugue, it may be best to NOT to follow this exposition with any episodic material; all that's really required is to connect this fine exposition with the big Neapolitan 6th chord at the end of this variation by means of additional entries of 4 bars each, with the companion subject and its 3 countersubjects appearing in various combinations of voices.
This might begin with a (5th) redundant entry, the purpose of which would be to display the counterpoint between the 1st countersubject (inverted c.f.) entering for the first time in the bass with the companion subject entering again (redundantly) in the soprano.
Two more entries in the home key might then be included to allow the bass to carry the 2nd and 3rd countersubjects at least once before modulating to the subdominant key (F Major) for the final entry.
This final entry might carry the companion subject in the soprano and the inverted c.f. (1st countersubject) in the bass, thus employing both outer voices (those most easily heard) for these 2 all important melodic lines.
Introducing a very lively passage of quadruple counterpoint into a fugato variation like this, where the voices first pile up one by one in a fugal exposition and then continue, creates a crescendo effect and can become thrillingly dense when all of this complexity is being successfully coordinated.
In order for there to be another sense of crescendo when the music comes to a stop on that big Neapolitan 6th chord it will be necessary to reduce the voices down to 3 parts, then 2, just a little in advance and then quickly reintroduce the 3rd and 4th voices suddenly just ahead of that big chord.
This may also be written into the score to give that big chord a little more "punch" when the music lands on it.
It will also help the listener to recognize this big chord as a Neapolitan 6th if there is a quick return to the home key, or its parallel minor, one or 2 beats in advance of it.
A stream of chords moving in parallel motion is commonly known as "planing;" chromatic planing occurs when such planing moves in half steps, ascending or descending.
If part of the c.f. happens to work with chromatic planing in the accompaniment, it would lend an interesting twist on this last variation; the melody in this case would probably need to be tweaked a little, with some of its notes moved perhaps to a different octave, to accommodate such a harmonization and to avoid some nasty dissonances, but, if it manages to work, it can be extremely effective [See blog, Marching, Your Ideas].
We might then round it all off by creating a short coda, still in 4 part texture, with the music gaining energy from the subdominant key by working the companion theme (not the c.f.) in imitation at the octave again, with a sudden turn into the home key at the end, finishing with crushing C Major chords in let's say 7 voices under an inverted pedal point in the top line using the full power of the instrument.
By going back and incorporating triplets in our introduction, there will be a rhythmic connective between the opening fanfare and the accompanying figure in the opening statement of the c.f. which follows, since we're using triplets there.
We might also consider introducing a melodic connective in this introductory passage by working the theme here in rhythmic transformation in big chords in the right hand against a moving bass line built upon the first few notes of the c.f.
The c.f. when it immediately follows will then seem to evolve naturally from the introductory material.
If the introduction is energetic, and we feel the need to apply the brakes and reduce the energy level a little bit before the c.f. is first presented, we might insert a pause, then include some slower chords at a reduced dynamic built upon a bass line using the first 3 notes of the c.f., pause on a discord, then begin.
This was the general scheme of variety within unity which was followed when Variations on a cantus firmus in C Major Op. 4 was written.
It takes guts to attempt or even contemplate doing something like this, but in the end the rewards of trying are infinitely greater than never trying at all.
To say to one's self that we're not capable of learning how to write something like this, that we're not a creative individual, is ridiculous; ALL human beings are creative; it's part of the human experience to be creative, to want to make something, to build something new, from our own imaginations; every human mind comes programmed this way, straight from the factory, by the Almighty Creator Himself.
It's much better to be out in the arena moving around, actively engaging in some kind of activity that raises us to a higher level of attainment (even if we're a little scared or maybe not as successful as we'd prefer with each and every attempt) than to be up in the stands or out in the parking lot procrastinating our entire lives, fueling Resistance with fear and doubt at every turn, and letting it destroy our desire (See blog, The Book].
Doubt has destroyed more dreams than failure ever has.
As the old saying goes, there's still plenty of good music to be written in the key of C Major, but the best advice is: don't try to make every composition a masterpiece; instead, write as a method of learning -- write and write, and write some more, in order to learn from the process.
We seek not perfection at every turn; perfection is the art killer.
We strive for excellence instead.
The rest will come.