Can you tell me the story of Boss Dharamsee and the grapes? I've heard it's a good example of how Baba works on an individual's ego.

Certainly. The story from Chapter 35 details the visit of Boss Dharamsee, who was initially skeptical. When Kaka offered grapes with seeds to Baba, Baba began distributing them. Dharamsee disliked this variety and was hesitant to eat them, especially since they were unwashed. He even thought that if Baba were a true saint, he would know his dislike. In response to this thought, Baba gave him even more grapes. When Baba commanded him to eat them, Dharamsee obeyed and was astonished to find they were completely seedless. This miracle shattered his 'clinical scrutiny,' his ego dropped away, and he was filled with love for Sai, resolving to visit Shirdi again.