Why does Chapter 32 place such a strong emphasis on the Guru's grace, and what metaphor does it use for worldly existence?

Chapter 32 strongly emphasizes that a Guru's grace is indispensable for attaining true knowledge. The text states that even if one has exhaustively studied the Vedas, Vedangas, and other scriptures, all that learning is "mere chaff" without the Guru's blessing. The words from Sai Baba's mouth are described as being powerful enough to destroy sins and, most importantly, to cause one to see their own Guru. To illustrate the predicament from which the Guru saves us, Chapter 32 uses the metaphor of the "tree of worldly existence." This tree is described as having its roots above and its branches spreading immeasurably. It is filled with birth, death, and sorrow, and its nature is perishable, highlighting the necessity of a Guru to escape its entanglements.