Reading a Progression: Everything at Once
You now have every piece: three functions, four cadences, substitution, the minor key’s borrowed dominant, secondary dominants, modal borrowing and modulation.
This lesson is not new material. It is the order to use them in, because knowing seven techniques and not knowing which to try first is barely better than knowing none.
The procedure
Given a progression you have never seen, in five questions.
1. What key is it in? Look at the first chord and the last. Most music starts and ends at home, and when the two disagree, the last one is usually right — that is where the piece decided to be.
2. Number everything against that key. Write the numerals under the chords. Most of them will be diatonic, and the ones that are not are the whole point of steps 4 and 5.
3. Where does it end? Find the last two chords and name the cadence. This tells you what kind of unit you are looking at: something that ended, or something waiting for an answer.
4. Any chord that is not in the key — what is it doing? There are three likely answers, in order of how often they turn up:
- It has a raised third and points a fifth down: a secondary dominant. Name what it points at.
- It has a flattened note and does not point anywhere: modal borrowing. It is a colour.
- It is followed by a cadence somewhere else: a modulation. Go back to step 1 for the rest.
5. What is left is structure. Group the diatonic chords by function — home, away, tension — and the shape of the phrase falls out of the numerals you have already written.
Worked through, once
Take C – A minor – D7 – G – C.
Step 1: starts and ends on C. Key of C major.
Step 2: I – vi – ? – V – I. The D7 is not diatonic: D–F♯–A–C, and C major has no F♯.
Step 3: the last two are V–I. Authentic cadence. This is a complete unit that ends.
Step 4: the D7 has a raised third and it is followed by G, a fifth below. Secondary dominant: V7/V.
Step 5: what is left is I – vi – (V7/V) – V – I. Tonic, tonic-substitute, an approach to the dominant made into a small event, dominant, home. The sentence from the first lesson, with one arrival strengthened.
Five questions, and a progression that looked like it had a mystery chord in it turns out to be the most ordinary sentence in the language, said with slightly more emphasis.
What to do when it does not work
Sometimes step 4 gives you a chord that is none of the three. That is not a failure of the procedure — it is the honest edge of what this module covers, and there is a great deal past it: altered dominants, chords borrowed from modes other than the minor, progressions built on symmetry rather than function, and music that is not functional at all.
The procedure’s real value is that it tells you quickly when you have left its territory. Four of the five questions will still answer. The one that does not is where the interesting thing is.
The thing worth keeping
Across ten lessons, one idea has come back three times in three disguises.
A secondary dominant and a chromatic II are the same sounds and different chords. A borrowed ♭VI and a diatonic VI are the same degree and different chords. A pivot chord is one set of notes with two names, one on each side of a modulation.
Every time, what separated them was function — what the chord is doing and where it is going — and every time, the written numeral was what recorded it. That is what this module has actually been teaching. The chords were the examples.
Where to go next
Take a song you already know and run the five questions on it. Not a hard one: something with four chords that repeat.
You will find one of the patterns from lesson four inside almost anything, and finding it yourself, in music you chose, is the point at which this stops being a set of lessons and starts being something you can hear.