What is the 'logic of the branch and the moon' as described in Chapter 22, and how does it relate to Sai Baba?

The 'logic of the branch and the moon' is a concept mentioned in Chapter 22 to describe how one can be guided to see something subtle, like the crescent moon, by first pointing to a more obvious object, like a tree branch near it. The chapter applies this logic to Sai Baba's physical form. It describes how devotees longed for a divine vision, and Baba would fulfill this by sitting with his right foot over his left knee. By grasping his big toe, which had a nail shining like the crescent moon, devotees could fulfill their curiosity for a vision. As Chapter 22 explains, this was an easy way Mother Sai showed His devotees to find Him.