The Advancing Guitarist has influenced countless professional guitarists (from Kurt Rosenwinkel to Julian Lage). It remains in print and is often cited on forums, college syllabi, and in masterclasses as a text that can take years to fully absorb—and that’s the point.
This is the section that breaks most players. Goodrick suggests (provocatively) that you tune your guitar so that open strings spell a C major scale (C-D-E-G-A). The moment you do this, every open string becomes a chord tone. The PDF explains why this unlocks harmonic thinking, even if you never actually retune. Mick Goodrick - The Advancing Guitarist.pdf