How does Chapter 20 explain the importance of having a Guru for understanding complex spiritual texts?

Chapter 20 powerfully argues that a Guru's grace is indispensable for spiritual understanding. It states that the Upanishads contain the essence of the Vedas and are 'very difficult to grasp' without the grace of God and a Guru. The text explicitly refutes the idea that a scholar can comprehend these texts through their own efforts, claiming the 'hidden truth does not come to hand' without a Guru. As Chapter 20 concludes, for one who is devoted to the Guru's feet, there is no difficulty, and the hidden meanings of scriptures open up automatically.