Shu Ha Ri is a Japanese martial arts concept that describes the three levels of learning.
I have always liked the concept since it provides a simple model that can help with communicating with people. The idea is to be aware of the level of your audience and match your message to their level. For example if you are an expert trying to explain a beginner how to do agile software development quoting principles only frustrates him; he needs practical advice to practical problems - not spiritual guidance.
Shu: Imitation, learning rules and individual techniques, tradition
Ha: Understanding, learning exceptions to rules, adapting techniques, breaking from tradition
Ri: Mastery, transcending the rules; flow, intuitive use of techniques
The Shu level is all about following the master and learning the rules. You don't really understand the big picture yet so you follow the book as best as you can.
At Ha level you have gained deep understanding. You understand why certain techniques work and can choose the best one for the situation. You also understand the limitations of techniques and when their use is not appropriate and when not.
By the time you reach Ri level you apply techniques naturally without thinking. You have transcended the rules.
Last year in Nääsvillen Oliopäivät Alistair Cockburn began his keynote by describing Shu Ha Ri. After his talk a member of the audience asked a longish question about a problem in applying agile in his organization. Having explained Shu Ha Ri just moments before, Alistair begun his reply:
You expect a Shu level answer to a Ri level question.
Shu Ha Ri by Alistair Cockburn
Three Levels of Audience in Ward's Wiki
What is Shu Ha Ri? an excellent blog entry by Kevin E. Schlabach