The sentence theme type

The sentence in music is regarded as the most important theme type in Classical music.[1] It occurs in many other styles of music as well – see the note on fragmentation for some examples – and is a quintessential part of a composer’s toolkit when writing any kind of melody-driven music.

Most of the time…

In my own experience, a sentence is usually just an 8-bar structure with this kind of layout:

  • 2-bar idea (this idea usually has 2 motifs)
  • Repetition of the 2-bar idea, maybe with some variation
  • 2 bars incorporating fragments of the original 2-bar idea causing a feeling of “forward motion”
  • A 2-bar cadential progression to cap off the theme

This is mostly how composer Ryan Leach describes it in this video.

hutchinson-2017 defines it even more loosely here:

  • Melodic idea
  • Repeat that idea
  • Some additional material (maybe from the initial idea, maybe not) that leads to a cadence

The simple sentence encapsulates above descriptions.

Abstractions

The sentence can be defined using “functions”, each of which convey a feeling of “a place in time” within the theme. In order, a sentence consists of:

  1. A presentation function – the “beginning”
  2. A continuation function – the “middle”
  3. A cadential function – the “end”

Again, each of these functions is meant to convey the feeling of being at the designated point in the theme. For example, the continuation function is designed to make the listener feel as though they’re in the middle of the theme.

Practically speaking…

The abstractions help us to analyze sentences that do not fall into the “simple sentence” structure. This occurs often enough in Classical music. However, when starting out in the world of composing, the simple sentence format is “good enough”. If it works for Koji Kondo, it should work for you!


References:
[1]: caplin-2013 p.33