The same room, with the light turned down.
The Chord
The minor triad is the major triad’s shadow twin, built from the same three-note skeleton with a single crucial difference: the third sits a half step lower. Where the major stacks a major third then a minor third, the minor reverses the order — a minor third on the bottom, a major third above. On C that gives C, E♭, and G. The fifth is identical to the major triad’s, so the whole change of mood rides on one lowered note.
That flattened third is the entire emotional argument. It pulls the chord’s brightness inward and downward, softening the arrival into something more reflective. The fifth still grounds it, so the minor triad is stable — it simply resolves to a darker room.
Structure
| Attribute | Value |
|---|---|
| Formula | 1 ♭3 5 |
| Notes (on C) | C E♭ G |
| Symbol | Cm |
| Quality | Sad, soft, introspective |
Character
“Sad” is the shorthand, but the minor triad is subtler than that. It can be mournful, but it can also be gentle, contemplative, warm, or quietly heroic. The lowered third gives it interiority — a sense of turning toward the self rather than outward to the crowd. Composers reach for it when they want depth without collapse, feeling without spectacle.
In Practice
The minor triad is the tonic of every minor key and the ii, iii, and vi of every major one. Its interplay with the major triad — the tension between a bright I and a shadowed vi — drives an enormous share of popular songwriting, from the vi-IV-I-V loop of countless pop hits to the aching tonics of folk ballads. In Musical Keys it defines the relative minor’s home. pytheory treats it as the major triad with a flattened third, exactly as the ear hears it.