The principles/guidlines of classical, real music
. Modern musicians tend to neglect music
theory or have
little knowledge of it. However, most knowledgeable musicians have
a basic idea of theory. (Steve Vai and Yngwie Malmsteen to cite two)
Person 1: "Hey, play me a Em, FM, and GM in common
time so I can put together a solo using the Em scale."
Person 2: "Whats common
Person 1: "Oh great, I'm jamming with a moron."
You look like an asshole when
you don't know music theory.