CH2) Circle of Fifths

Did you know the circle of fifths also unfolds the seven diatonic pitches of major scales and the system of key signatures?

The pitches F-C-G-D-A-E-B are the seven diatonic pitches of C major. Proceeding clockwise, the pitches C-G-D-A-E-B-F# show the seven diatonic pitches of G major, and so on. As it proceeds counterclockwise, the pitches Bb-F-C-G-D-A-E show the seven diatonic pitches of F major, a Bb major gets Eb-Bb-F-C-G-D-A, and so on. This is why the fifth is important in tonal music (mathematically speaking), representing the tonic (center), dominant (fifth up), and subdominant (fifth down) as the three primary pitches that define the key.

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This is also why the organization of the key signature system adding sharps or flats is a fifth apart each time:


F# – C# – G# – D# – A# – E#(F) -B#(C)
Bb – Eb – Ab – Db – Gb – Cb(B) – Fb(E)