Based on the teachings in Chapter 20, what is the importance of a Guru's grace in understanding profound spiritual texts like the Upanishads?

Chapter 20 strongly emphasizes that understanding scriptures, which contain the science of Self-knowledge, is nearly impossible without the Guru's grace. The text states that the Upanishads hold the essence of the four Vedas and are very difficult to grasp. It warns that even a scholar's own efforts will fail to reveal the hidden truth, as the path is difficult at every step without a Guru. However, as this chapter explains, for a devotee attached to the Guru's feet, there is no difficulty at all. For such a humble and detached person, the hidden meaning opens up automatically, making the Guru's grace an indispensable key to true spiritual comprehension.