George Gershwin · 1935 · B♭ major · AABA, 32 bars
The turnaround again, this time with the vi made a dominant. Gershwin wrote so many tunes on this skeleton that the skeleton itself became the sound of the era.
Analyzed excerpt
Section: A1 · Bars 1–5
Bb | G7 | Cm7 | F7 | Bb
This is a short excerpt quoted for analysis, not the full chart, and this composition is very likely still in copyright. Published versions and recordings disagree with each other about the rest of the tune, and often about these bars too.
Every one of these tunes is assembled out of the same handful of harmonic resources. Jazz Harmony is those resources, explained in the order in which they build on each other.
| Chord | Roman numeral | Function | What it is doing | Confidence |
|---|---|---|---|---|
| Bb | I | Tonic | Bb is the tonic of Bb. It is where the progression is at rest. | High |
| G7 | V7/ii | Dominant | G7 is functioning as V7/ii: a secondary dominant. It is the dominant of C, not of the home key, so it borrows the pull of a V-I and points it at ii instead. | High |
| Cm7 | ii | Predominant | Cm7 is the ii chord of Bb: the classic predominant. It prepares the dominant and almost always moves to it. | High |
| F7 | V7 | Dominant | F7 is the dominant of Bb. Its third and seventh form a tritone, and that tritone is what makes the tonic feel due. | High |
| Bb | I | Tonic | Bb is the tonic of Bb. It is where the progression is at rest. | High |
A complete ii-V-I in Bb. Predominant, dominant, tonic: the sentence jazz harmony is built out of.
The progression closes with an authentic cadence in Bb.
High, medium and low next to each numeral are judgements about musical context, not probabilities. A low rating marks a bar that can honestly be read more than one way. How the ratings are decided →
Numbered against Bb major, the excerpt is I – V7/ii – ii – V7. Inside those 5 chords there is a complete ii-V-I and at least one secondary dominant. Take the roots away and keep the third and seventh. In G7 that is B and F. Those two notes decide where the progression is going, and hearing them move is worth more than naming the chords. Stella by Starlight, How High the Moon and Ornithology use the same device, which is the argument for learning it once properly rather than three times by accident.
A thirty-two-bar song whose A sections move through secondary dominants at a steady, almost march-like rate, giving the piece its characteristic forward push. The melody is built from short repeated phrases with rests between them — written for a character to sing while moving around a stage, and the gaps are where the acting happened. The bridge is conventional and short, which keeps the momentum from breaking.
From Porgy and Bess, 1935, with a lyric by Ira Gershwin and DuBose Heyward, sung by the title character. It is less often played than Summertime from the same score, but it appears on the 1958 Miles Davis and Gil Evans orchestral recording of the opera, and that arrangement is the reason it is in the instrumental repertoire at all.
Open these chords in the analyzer and change them. Move one chord, substitute a dominant, take the ii away — the reading updates and tells you what you just did.
What this device is, and the other standards in the library that use it.
Read →What this device is, and the other standards in the library that use it.
Read →Victor Young · 1944 · B♭ major
Chord progression →Morgan Lewis · 1940 · G major
Chord progression →Charlie Parker · 1946 · G major
Chord progression →The families every standard is assembled from, with examples from the library.
Read →