What does Chapter 18 say about the role of the Sadguru in revealing the ultimate truth?

Chapter 18 glorifies the Sadguru as the one who reveals the ultimate truth, which is otherwise difficult to grasp. The text states that the Sadguru is the 'teacher of the knowledge of the Self.' It further explains that the very same 'Unperceivable One' that the Vedas and Shrutis debate endlessly is pointed out effortlessly by the Guru to His devotees. As described in Chapter 18, the Sadguru is the supreme eternal one, the Truth of Brahman, who, through direct experience, shows the world to be an illusion. This highlights the Guru's indispensable role in guiding a seeker to self-realization.