I ran across an article in "teachers at work" talking about how to use threes effectively in your writing. This made me think about another quirky thing about the mind, that is, how we have the minor pentatonic scale seemingly hardwired into the brain.
Three is very significant in music. From the standpoint of chords, it is the third that is the biggest determinent in the sound of the chords. Change from major seventh to minor seventh, and the change is subtle. Change the third and the change is drastic. It is the third that separates a major from a minor. And you use thirds to build larger chords. Start with a major third, you set the stage for any other notes that you place on top of it. If you then add a minor third to the previous two notes (first and third) you come to the fifth note in the scale that your chord is built from. These three notes, first, third and fifth, form your fundamental chords. So again we find three. Not only is three fundamental in the 'tone' of the chord, it is with three that you build your fundamental chords, and three notes make up a fundamental chord.
It is not only three that seems to get so much unconscious attention. There are other significant numbers to be found in the psyche, as it is so in music. The root, the essential determiner for a scale. The third, the primary determinant for a chord. The fifth, the note that works well with just about anything. Speaking of five, the minor pentatonic scale seems to be ingrained in the Human mind. If you go to the World Science Festival website and check out the video entitled "The power of the pentatonic scale" you will see what I mean.
So I suppose this raises the question, why are certain numbers hardwired into the mind?