The concept of Shu Ha Ri comes from the Japanese martial art of Aikido. I spent some years in an Aikido dojo in Denver (Sensei was in Ha state) and in Cambridge (Sensei in Ri state). The student enters in the Shu state and must exactly follows the instructions of the Sensei. By the time the student gets a black belt, s/he has achieved the Ha state and can execute the practice with excellent form, inspecting and adapting constantly to improve. The Ri state is different. The Sensei moves his arms and people fly across the room without having to touch the opponent. Of course, if you haven't seen a master of the chi force, you may not believe this is possible.
The Shu Har Ri concept can be used to consider what qualities make a great ScrumMaster? And what does a ScrumMaster do in each state.
In the Shu state, the ScrumMaster sets up the process, helps the team get to a sustainable pace with known velocity and uses the Retrospective to introduce change that improves velocity.
In the Ha state, the ScrumMaster has a team that gets software done (all features tested and no bugs) at the end of the sprint and has a good product owner with ready backlog at the beginning of a sprint, has data that clearly show at least a doubling of productivity, and has strong management support. The team is positioned to work on hyperproductivity, the design goal of Scrum.
In the Ri state, the team is hyperproductive. But what is the ScrumMaster doing and do you really need one? You need the ScrumMaster but they don't have to do much. Here is an example of the qualities to look for if you want a Ri state ScrumMaster.