Vertical Truth is a series of method books that apply the principles of music theory to the guitar. This method does not deal with music theory in the abstract but is guitar-specific. However, the principles learned are universal and can be applied to any instrument.
 

Vertical Truth is not designed as a "self-teaching" method but requires a knowledgeable instructor.
 

Ask yourself these questions;
 

Have you ever sat in a music theory class wondering what the rules of the four-part Bach chorale style have to do with the guitar?
 

Have you ever heard some awesome guitarist play and wondered how anybody could know so many chords?

 

Or what bizarre scale is he using that sounds so cool?

 

Does this symbol look like some kind of calculus problem?