Could you provide a summary of the key events and teachings presented in Chapter 20 of the Sai Satcharitra?

Chapter 20 of the Sai Satcharitra begins with invocations and then paints a vivid picture of the scene at Shirdi after the noon Aarti. It describes Sai Baba mercifully distributing Udi to his devotees, applying it to their foreheads with boundless love, and then sending them to their lodgings for a meal. As detailed in the chapter, the narrative then shifts to introduce the story of Das Ganu, who was writing a commentary on the Ishavasya Upanishad. He encountered a deep doubt he couldn't resolve and brought it to Baba. The chapter concludes by setting up the next part of the story, where Baba tells Das Ganu that his doubt will be cleared by a simple maidservant, emphasizing the importance of Guru's grace over scholarly effort.