How does Chapter 20 explain the necessity of having a Guru for spiritual understanding?

Chapter 20 strongly argues that a Guru is essential for comprehending profound spiritual texts like the Upanishads. The text states that the Upanishads contain the essence of the Vedas and are "very difficult to grasp" without the grace of both God and a Guru. It explicitly refutes the idea that a scholar can understand these texts through their own intellect, saying such an effort will fail "even at the end of an era." Conversely, Chapter 20 assures that for a devotee attached to the Guru's feet, there is no difficulty, and the hidden meanings of scriptures will open up automatically. This principle is the central theme of Das Ganu's story within the chapter.