Jim I’s Blog

What in the world is the “Circle of Fifths”?

There are inherent mathematically definable relationships that exist in Western Music. While music theory is not needed to write or play music, I do sometimes marvel at the way it fits into our psyche or maybe how we fit into the bigger picture. Is music structured to fit our perception or is it a reflection of something bigger that our perceptions fit into? You have to wonder why music is so universally accepted by people and why it is so important to movies, TV shows and various forms of live entertainment. Before we get too esoteric lets explore the basic structure of harmony. Then we can see how major scales are derived from these relationships.

We’ll need to start with some basic facts. The strongest harmony is an octave. If you look at the black and white keys on a piano you will notice wherever you start there will be 12 notes between there and the next octave (whether you go up or down). The smallest increment in Western music is a half step, the distance from one key to the next adjacent key (whether it is a black or white key).

After an octave the next strongest harmony is the perfect fifth. It consists of 7 half steps (adjacent keys – or frets if you’re a guitarist). The next strongest harmony is a perfect fourth which is made of 5 half steps. We are going to stop defining harmonies here because that is all we need to show the relationship between all the major keys.

An interesting side note that supports the assertion that there are mathematically definable relationships is the fact that an octave is made up of a perfect fifth on top of a perfect fourth. keeping that in mind the circle of fifths starts at C major, which has no sharps or flats. if you go up a perfect fifth you come to G major which has 1 sharp (it is F#). If you go up another perfect fifth you come to D major which has 2 sharps (which are F# and C#). This continues, keep adding a perfect fifth on top and the major key keeps adding a sharp.

Conversely if you go down a perfect fifth the major key adds a flat. Going down a perfect fifth from C you will find your self a F major which has one flat (Bb). If you head down another perfect fifth you come to Bb major which has two flats (Bb and Eb).

We’ll stop there until next time.

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