I've recently started playing my guitar again. I haven't seriously played in...well, forever. I'm an on and off dabbler--more off than on, and by "on" I mean, at best, I'd put in twenty minutes of practice per day. I have an acoustic and an electric. My nine-year-old daughter has been interested in practicing with me, so we each have one to play on.
In my ineptitude, I confused and frustrated the heck out of her the other day when she asked to learn the notes' names. She has a keyboard with note stickers on each white key; but when I showed her a diagram of all of the notes on a guitar, I thought that she was going to explode.
The above diagram is much harder to understand than the one for a keyboard because, on the latter, the notes are in a straight line. Not only are the notes on a guitar strung over six strings, but they actually overlap. For instance, the fifth fret on the sixth string is "A," the same as the open fifth string. From a beginner's point of view, the fact that the exact same note can appear twice on a guitar can be very confusing.
What else can be disconcerting is that the guitar can be tuned so that the notes for the open strings change. None of the notes have a fixed position. This means that all of those scales you spent so much time memorizing are no longer in the places where you practiced them! The same applies to chords. They can be moved, depending on how you choose to tune your guitar.
This is a startling example of relativity. The note "A" is still "A," but its location can change, just like in ordinary life. The scales that we use to determine values are continuously sliding. What is correct in one situation--eating with your elbows on the table--is incorrect in another context--at a formal dinner, say.
Values change with context. A man may be nice to his coworkers and cruel to his family, or vice versa. A 30-pound dog may look huge beside a Chihuahua, but tiny next to a Great Dane. Context is critical. But the human mind loves to generalize. It wants some view that it can apply to every situation, yet life doesn't work that way. Nothing is constant or absolute, just like an "E" on a guitar can appear in several places on any string; its location is not set. Neither is our identity.
Zen practice teaches us how to respond to each situation as though it were fresh, because it is. Every moment is uniquely unreproducible, and with each new event, the context changes. Useful concepts in one scenario can cease to be helpful in others. In a sense, Zen teaches us how to move our E's, to down tune ourselves to meet every situation with as much balance, poise, and skill as we can.