According to chapter 10, what is the significance of the Guru in a devotee's life and how does one cross the 'ocean of existence'?

Chapter 10 emphasizes that the Sadguru is the one eternal God, while other gods are illusory. By placing faith in the Guru's feet, a devotee can have their fate changed, an idea expressed with the phrase that He "strikes a nail over the lines of destiny." The text explains that to cross the worldly ocean of existence (Bhavasagar), one must place complete trust in the Guru, just as one trusts a boatman to cross a physical ocean. The chapter states that when the Sadguru becomes the boatman, devotees can overcome the three types of miseries—physical, mental, and divine—and He effortlessly bestows upon them knowledge (Samvitti) and liberation (Moksha).