What does Chapter 22 mean by the "logic of the branch and the moon," and how does it relate to having a vision of Sai Baba?

The "logic of the branch and the moon," mentioned in Chapter 22, is an analogy explaining how a physical or gross object can be used to point towards a subtle, more distant one. Just as someone might point to a nearby tree branch to help another person locate the faint crescent moon, Sai Baba provides a tangible focus for his devotees. The chapter explains that devotees' deep curiosity for a spiritual vision is fulfilled by focusing on Baba's foot. Specifically, it describes how the nail of his right big toe, when he sits in a certain posture, shines like the crescent moon. This concept from Chapter 22 illustrates how the Guru uses His physical form to guide devotees toward a divine realization that might otherwise be difficult to perceive.