I'm reading your book through from cover to cover. I have a question that I imagine you will answer later in the book but I thought I'd send it out anyway. You say that all modern music is derived from the major scale. But what about tunes that have a minor sound? Or for that matter, a blues sound?
Great question! The first thing you should know is that as soon as you begin practicing the IFR exercises, you will immediately discover all those "minor sounds" and "blues sounds" that you're talking about. In IFR we study and play all of these sounds. Here's how we approach these sounds in IFR:
1) You'll be improvising with both major and minor sounds right from the start. Just go to IFR Jam Tracks Level 1: Seven Worlds and play any of the tracks in the 2 chord, the 3 chord or the 6 chord. These are all minor chords, and the overall sound of the music is would you would call a "minor key". IFR will help you see how these chords fit into the big picture, and where these "minor sounds" actually come from.
2) Also take a look at IFR Standards Workout 1. Three of the standards in this course (Autumn Leaves, Black Orpheus and Blue in Green) are generally considered to be in a "minor key". But that's really just semantics. Regardless of whether a tune sounds "major" or "minor" to your ear, you can always visualize ALL of the sounds on the IFR Tonal Map. The IFR Tonal Map gives you a bird's eye view of the entire chord progression, allowing you to see how melodies flow in and out of the chords.
3) The "blues sound" that you mentioned is even more interesting. Blues music has many dissonant sounds like dominant chords, blue notes, bending, the "blues scale", etc. But remember, EVERY note you play is somewhere on your IFR Tonal Map. The IFR Tonal Map includes all 12 notes of the chromatic scale, so there isn't a harmonic concept in the world that can't be visualized and understood using the tonal map concept. The IFR Blues Mastery Course will show you exactly how this applies to the blues.
4) A final thought to keep in mind is that your palette of colors as an improviser is always the entire 12 note chromatic scale. The IFR Tonal Map includes all of these notes, so any phrase or melody from the "blues scale" or from any minor scale is already available to you. IFR doesn't impose any limits at all on what you can play. In IFR, our objective is to see the entire musical landscape and to know where EVERY sound is located. This is what gives us the freedom to express any sound we can imagine.
I hope this helps fill in the blanks a little bit. If you have more questions, just let me know.