First came music; then came music theory. Music theory is merely a way to explain in an understandable way what came before it. Music theory has many practical applications because it deals with explaining sonic events in literary terms. When you hear a piece of music, trying to explain what you've heard in words can be trite and ineffective. Calling a Hendrix solo “powerful” or “moving” doesn't explain the music at all; all it does is convey an emotion that you felt while listening. While it may be more convenient to describe a piece of music as a magical moment of inspiration, the reality is that there is always something to extract from the music in terms of theory and something you can learn from it.

When you have a concrete name for something you've heard, you have the key to repeating it whenever you want. It's akin to stumbling upon a great restaurant by accident, and not asking for directions back. If you'd like to eat there again, you should ask for directions. If you hear a great chord change, or a melody that sounds unusual, to let it fly by you seems silly if you would like to integrate it into your own music. If you could figure out what you were hearing, then you would be able to recreate it in your own music.

The System

Music is based on a system that has been repeating and slowly evolving since music began. The system that holds music together is based on the interval. An interval is a measure of distance between notes—a measuring stick for musical distance. When melodies are played, the distances between the notes are intervals. When you play intervals in specific orders, you can build scales. When intervals combine and are played simultaneously, you get chords.

The focus of this chapter is on intervals. Once you understand intervals, you'll be ready for the other music theory that is integrated throughout the rest of this book.

Straight-Line Theory

The guitar can be a wonderful instrument to study theory on, but it can also be a nightmare! It all depends how you look at the instrument. Music theory is best presented in a straight line, with everything happening consecutively one step after the other. On the guitar, to see music in a straight line, you must play across one string, meaning that you stay on one string for an exercise and you don't move, or shift, strings. You do this only to learn theory, because trying to play this way can be laborious and difficult. Being able to see the intervals based on fret distance will let you see and hear the relationships in ways that scale shapes don't let you see.