«How do I continue this piece?»
This is the most common question I see beginner composers ask. To help you solve this problem, I will teach you a technique I myself have used countless times when I've gotten stuck. This technique is very concrete and simple, but also powerful, as it will give you a jumping-off point every time you want to write new material.
It's in the nature of a continuation that it will consist of something new - otherwise you'd already have repeated your material. However, we also want some form of connectedness, so the new material doesn't feel like it's a different piece of music entirely.
The meaning of "new" is a bit amorphous in this context, but we can use a different word. Any material that is new will per definition carry with it some degree of contrast to the material that has already been established - and contrast is something we can systematically play with. That's what we'll do in this article!
For demonstration purposes, I will use redoxwarfare's Comet Cruiser. Time to get to know the piece!
Step 1: Analysis
Listen to the A section for the first 42 seconds of the song and write down 5 - 10 musical traits that you could describe this material with. If you need some ideas, you can use the composing checklist.
What sticks the most out to you? What facet is the most salient? What are some more subtle traits? Try to get a good variety of traits down, and rate them on a scale from 1 - 5 where 1 is a trait that is subtle, and 5 is a trait that is extremely striking. This will obviously be subjective, and that's what makes this interesting.
These traits can be anything from a particular rhythm to the tempo and register. You can also describe moods. It's really up to you and what you find most helpful personally. It might be easier if we start with more concrete musical traits though. We'll use four traits for the demonstration:
peppy/stabby rhythm (☆☆☆☆)
pluck melody (☆☆☆)
major key (☆)
high register (☆)
Listen to Comet Cruiser yourself and see if you can't come up with six more facets to describe the first section!
Now ask yourself: How big of a contrast is appropriate at this point in the piece? Do I want a completely new theme, or do I just want to spin the material gradually in a new direction? This will depend on a number of factors, but the most reliable ones are the amount of time that has passed since the beginning of the piece and how much contrast you have already introduced. The more time passes, the more of a refreshment the listener is likely to need. And similarily, if you've been elaborating on the same material for a while, it may be time to do something different.
Rate the amount of contrast you want on a scale from 1 - 5 where 1 is barely noticable contrast and 5 is a complete break away from everything that is going on.
Step 2: Inversion
Now we will invert a number of the traits on our list to find the opposites that will be featured in the new section.
flowy/arpeggiated rhythm (☆☆☆)
sustained melody (☆☆☆☆)
major key (☆)
high register (☆)
By choosing our contrasts from the material we already have, we will make sure the contrast feels relevant.
Note that we only inverted half of our list. Depending on the number you came up with to describe the appropriate contrast level and the numbers you came up with to describe the salience of each trait on the list, you may want to invert more or fewer of the words on the list. You can play around with the scores in many different ways.
However, don't think about this too mathematically either. The contrast has to be felt first and foremost. We're just using the systematic approach to clarify our thinking. Let's look at the result:
The greatest benefit of a systematic approach like this is that you now know what to do when you don't know how to proceed. Instead of a large, amorphous problem, your problem is now concrete and game-like. Make a list, invert some words and immediately get on with the problem of finding a cool flowy rhythm.
If you find it hard to decide which words to invert, consider this: It doesn't matter. Just throw a dice if you want. This goes back to my old adage that "if you don't have a clear idea of how to proceed, it doesn't matter how you proceed". If you don't have an opinion, then all roads are equally valid. By trying something, you will quickly notice whether you like, dislike or feel indifferent toward it. Just do something. It doesn't matter what. It will be fine.
Now that we have a list of traits we want our B section to consist of, we can get to work composing. However, there are still some things that can be useful to consider.
Extra step: Motivic development
We have now made sure that there will be some new traits that will add contrast and interest to the new section, and we have also made sure some traits will stay the same so that it doesn't feel like a completely new piece.
We have decided that the new melody will have a sustained, legato character, so should we just write a new melody then?
This is where motivic development comes into play. To make sure that the new melody sounds connected to the melody that came before it, we will not just write a new melody from scratch, but use the melody we already have and alter it in interesting ways.
If you're unfamiliar with motivic development, I recommend reading my articles on the topic here and here before proceeding.
We are looking for a B theme with a more sustained character. Since the previous melody had a lot of quick notes, we can now take those notes and augment them so they become twice or four times as long, just as an example.
Can you hear or see any motivic similarities between the A and B themes in Comet Cruiser?
You will rarely be able to only use one development technique and get a completely satisfying melody, so we may have to be flexible and alter things that sound off or weird, but that's okay! Development algorithms are rarely complex enough to create satisfying material by themselves. See this as an opportunity to engage your musical intelligence.
Motivic development is a pretty sophisticated technique. The changes we make to our material won't be immediately apparent to the listener (and most untrained listeners will never notice), but it will still create a connection between them that will be picked up on subconsciously. The two themes will feel related, like a brother and sister.
Strategic Contrast
Another thing I want you to consider is the contrast that emerges from all the smaller contrasts you introduced in the new section.
If you contrast a major key section with a minor key section, what kind of «story» is told there? What is the flavor of that contrast? Compare it to a different contrast, maybe one of rhythm, and try to describe to yourself how it feels different.
What you contrast something with tells you what it is. What is concrete compared to glass? Durable and threatening. What is concrete compared to wood? Inorganic and dead.
In other words, you can choose your contrast to highlight certain facets of the original material. If the most important facet of the A section is that it sounds happy, then consider writing a B part that does what it can do sound not-happy. When the B part then arrives, it will make the A part sound happier in retrospect.
The Contrast Space
Where there is contrast, there is also space. Every distinction between two opposites implies a road in-between. It would indeed be misguided to only consider the two sections in isolation. Together they form a whole that says more than the parts they are made of.
Think about a «summer evening».
Summer morning.
This is the story of the progression of a summer night. How did you spend it? Maybe you were sleeping. Or maybe you were out on the town.
Now if I again say «summer evening».
Winter evening.
We now have a story about the progression of seasons.
As you can see, both «summer morning» and «winter evening» are contrasts to «summer evening», but they tell different stories. The story is found between the lines, in the space that is established between the opposites.
This goes for music as well. Listen to the Ravel minuet below and consider the feeling that the contrasting section from bar 8 imparts on the music:
For me, the first 8 bars feels like a sunny summer day in the garden. The weather is warm and comfortable, maybe I'm in a bit of a daze. When the B section arrives with its planing minor chords, I get the feeling that the sun is for a moment covered by the clouds. Suddenly I realize the weather wasn't as warm as I thought, because now I feel eerily chilly, here in my hammock strung up between the trees.
How would you describe the contrasts that are introduced later in the piece? How does this summer day progress? Or maybe the story changes for you when you hear new material that conflicts with the story you were imagining. How would you write a contrast section to describe winter here?
As you gain mastery of the contrast technique, you can start to think more about the story you want to tell, instead of only thinking about the contrast on the purely musical level.
Final notes
This inversion technique is deceptively simple. Describing music and putting words down on paper is easy, but the technique's complexity lies in all the different words you can choose to invert.
On one hand you can invert relatively concrete and immediately salient musical facets like «tempo» and «key», but you can also invert more abstract words like «static» to become words like «dynamic».
Just think of the classical sonata form! One part of the form is dedicated to presenting melodies and another part of the form is dedicated to picking them apart and rapidly present their fragments in all sorts of new and weird circumstances. That is also a contrast, but a much more high-concept one.
The topic becomes even more complicated if you want to have more than one contrasting section. Now you need to consider the contrast between all the sections. You have to consider whether you want to design the parts so they are equally contrasting, or whether the contrast should be unequally distributed. Maybe save the biggest contrast for later in the piece when the listener is most craving novelty?
Look out for contrasting sections from now on, and try to describe to yourself which facets of the original material has been altered to become its opposite, and which facets stay the same. How is the contrast distributed over the course of the piece?
I'll leave it up to you to experiment with this for the time being!