What are the main events and teachings described in Chapter 20 of the Sai Satcharitra?

Chapter 20 of the Sai Satcharitra covers two primary subjects. First, it vividly describes the scene at Shirdi after the noon Aarti, where Sai Baba would lovingly distribute Udi to his devotees, applying it to their foreheads and sending them to eat. This section highlights his merciful nature. The chapter then introduces the story of Das Ganu, who was writing a commentary on the Ishavasya Upanishad. When he struggled to understand its deep meaning, he approached Baba. The text emphasizes that profound spiritual knowledge, like that in the Upanishads, is impossible to grasp without the grace of a Guru, a key teaching of this chapter.