Black Gospel Chords - The secret chords of praise and worship

Yes this product was exactly what I needed to take my music to the next level.

I know a good bit about music theory. But I was attracted by the title indicating substitutions etc.But I am very disappointed by this book. The author seems to have a system, but doesn't give any explanation about how to use it. And so I am completely lost. I can see that some of the suggestions make up a chord, but most are unplayable with one hand anyway.Maybe the book is understandable if you already are familiar with the other books, but otherwise, stay well away!