How does Chapter 20 explain the importance of having a Guru when trying to understand profound spiritual texts like the Upanishads?

Chapter 20 places immense emphasis on the necessity of a Guru for spiritual comprehension. It states that while the Upanishads contain the essence of the Vedas, their profound truths are very difficult to grasp without the grace of Hari (God) and a Guru. The text argues that a scholar's individual effort to comprehend these texts is futile, as the hidden truth will not be revealed even after an era. However, for a devotee who is attached to the Guru's feet, there is no difficulty at all; the hidden meaning opens up automatically before their eyes.