There is a big difference between "being classically trained" and knowing music theory. There are hoards of people out there who have taken years of piano lessons, violin lessons, clarinet lessons, or what have you, who can read music as easily as most people can read a newspaper, and who can play some very difficult music. Some of them even play in symphony orchestras and appear on concert stages. Assuming that they haven't memorized the piece, if you were to take the sheet music away from them, they'd be lost. They can't improvise because they don't know what to do. Because they don't know music theory from Shinola. And why not? Because many people have taken private lessons all their lives from teachers who didn't know music theory either. And believe me, teachers like that are in the majority. They've always played by rote from the written music without really knowing what it's all about. Or that there is a better—and easier—way to learn that will really put them in command of what they're doing.

Music theory answers such questions as "What is a scale? How does a major scale differ from a minor scale? What is their relationship? What is a mode? What is a chord? How can you construct chords? What's the difference between a major chord and a minor chord? How do they relate? What chords can I use [not must I use] to accompany this song?" Yes, and "What key am I in?" Music theory is not a list of rules and prohibitions. Quite the contrary. It shows you possibilities that you may never discover on your own. It's a logical and cohesive system that provides quick and easy answers to many of the questions that appear in these threads. And many of these questions are really very elementary. "What's the relationship between major and minor scales?" is something that's explained in the first dozen pages of any halfway decent book on music theory. (By the way, understanding modes and how they were and are used is far simpler than most people assume.)

If you play much, you'll learn this stuff as you go along. Can't help it. You can dope out a lot of it by yourself, and it's a real kick when you finally figure something out. But sometimes going through a good book on music theory guitar in hand leads to glorious light-bulbs popping all over the place. The difficult and incomprehensible suddenly becomes ridiculously easy. Exploring is fun, but sometimes you just can't find what you're looking for. So you pull out a map and suddenly, "Aha! So that's where it is!!"

Nobody imposed this on us as a duty, and we are free to learn any way we want. The main thing is to enjoy the exploration, whether we chose to go armed with a map or not.

Don Firth