Tritone chord substitution is the focus of this lesson. As with so many new concepts you learn, tritone substitution can be explored at many levels. Your own personal experience will reveal this. This lesson makes this must-know concept easy to understand. Altered tensions and unaltered tensions are given some attention. The first chords of I’ve Got The World On A String (Arlen & Kohler) and Georgia On My Mind (Carmichael & Gorrell) are used as examples. You’ll want to review this again and again as you will the other lessons. As a growing piano stylist, you will appreciate how Lesson #22 and this one work so well together as your personal musical choices continue to expand beyond belief!