How does Chapter 18 describe the supreme nature and qualities of the Sadguru?

Chapter 18 extols the Sadguru as the supreme Eternal one and the very Truth of Brahman. He is praised as the ruler of Maya, who makes the world's illusory nature apparent through direct experience. The text describes him as "Beginningless and Endless," "beyond duality," and "without blemish," establishing him as the ultimate teacher of Self-knowledge. As this chapter reveals, the Guru can effortlessly point out the "Unperceivable One" to his devotees, a concept that even the Vedas and Shrutis debate endlessly, showcasing his unparalleled spiritual authority.