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10.31Fully diminished seventh symmetry
Play:
B°7
Keyboard notes:
B D F A♭
Look at the distances:
B → D = 3 semitones
D → F = 3
F → A♭ = 3
A♭ → B = 3
The chord divides the octave into four equal minor thirds.
That symmetry gives diminished seventh chords unusual properties.