ideas for new chapters
Diatonic Sequences in Middles (in progress–no examples yet)
Overview
A sequence is a pattern that has been repeated and transposed (Example 1). The term “model” refers to the initial statement of the pattern, and the term “copy” refers to subsequent repetitions of the pattern. Sequence models are typically comprised of a two-chord pattern and a melody, and both the chords and melody get transposed in subsequent copies of the pattern. It’s possible for only the melody or only the harmony to be sequential. In such cases we usually specify “melodic sequence” or “harmonic sequence.” When we just say “sequence” it usually means both melody and harmony participate.
Perhaps one of the most challenging tasks in analyzing sequences is determining where the model and its copies are. Beginning analysts often identify things that are too short to qualify as a model for a pattern. It can be helpful to remember that the model should usually contain more than one chord, very often two chords. Example 2 shows why. Example 2a shows a pattern comprised only of circles, whereas Example 2b shows a pattern that alternates circles and squares. In 2b, it’s easy to identify what the pattern is that’s being repeated (circle–square). In 2a it’s unclear: are two circles being repeated every time? Three? Both? What is the model?
We can divide sequences into two main categories: those that descend and those that ascend. Within each of those categories, certain sequences are so common that scholars in the 20th century have given them special names. These are covered below. It’s important to emphasize, though, that these are not the only kinds of sequences. It’s just that these ones are quite common. Unnamed sequences might simply be labeled “ascending sequence” or “descending sequence.”
Descending sequences
Descending fifths (a.k.a. circle-of-fifths)
Descending fifths sequences involve a two-chord model being transposed down by step (Example 1). The sequence is called “descending fifths” because each successive chord root descends by fifth (or ascends by fourth—the inversion of a fifth. Composers do this to avoid writing an unreasonably large range which would happen if they kept descending by fifth). Sometimes, instead of using all root position chords, as in Example 1, composers choose to alternate root position and first inversion chords (Example 2).
Descending thirds (a.k.a Pachelbel)
Descending thirds sequences involve a two-chord model being transposed down by third (hence the name “descending thirds”) (Example 3). Some people choose instead to call this sequence “Pachelbel” after his Canon in D, which features a version of the sequence (Example 4). It’s common to see the sequence involve all root position chords (as in Example 4) or alternating root position and first inversion chords (as an Example 3).
Ascending sequences
Ascending 5–6 (a.k.a ascending step)
Ascending 5–6 sequences mimic a two-chord pattern by prolonging a single chord using som