Can you provide a summary of the main events and teachings found in Chapter 20 of the Sai Satcharitra?

Chapter 20 of the Sai Satcharitra begins by describing the scene at Shirdi after the noon Aarti. It details how Sai Baba, with a merciful gaze, would lovingly distribute Udi to his devotees, placing it in their hands and on their foreheads. The chapter then transitions to the story of Das Ganu, who was writing a commentary on the Ishavasya Upanishad. When he encountered a profound doubt he couldn't resolve, he sought guidance from Baba. Instead of a direct answer, Baba told him the doubt would be clarified by a simple maidservant. As Chapter 20 explains, this illustrates the principle that profound spiritual truths, like those in the Upanishads, are inaccessible without the grace of a Guru.