Why did Sai Baba appear in a physical body in Shirdi if he is the Supreme Brahman?

The text explains that Sai Baba's incarnation was a deliberate act for a specific purpose. Chapter 43 states that he appeared in Shirdi for the sake of the devotees' protection, gathered by their past merits and unmanifest devotion. These great beings, who can incarnate by their own will, take on various avatars with the sole desire for the welfare of their devotees. His time in a physical form was a task for the devotees, and once that task was considered over, he chose to leave the body. His physical manifestation was a spontaneous play of Yoga for the sake of his devotees' salvation, not a submission to the cycle of birth and death.