The Companion Book For DVD Guitar III & Guitar 1V Finally the Basics on Harmony Scales and Modes is an authoritative manual on the subjects and an in-depth study with examples that will make the light shine on these subjects. If you want to be a guitar player with the understanding of how to play in all keys with single notes and chords and move with ease all over the fret board, you need this book. What an eye opener. Basic harmony, extended harmony, modes, diatonic and pentatonic scales, the book explains them all.