What is the nature of the Sadguru as described in the opening of Chapter 18?

According to the introductory verses of Chapter 18, the Sadguru is praised with numerous victorious salutations. The Guru is described as the supreme Eternal one, the very Truth of Brahman, and the Ruler of Maya who shows the world to be an illusion. The text further elaborates that the Sadguru is beginningless, endless, beyond duality, and without blemish. Ultimately, as Chapter 18 states, the Guru is revered as the sole teacher of the knowledge of the Self, capable of effortlessly pointing devotees towards the Unperceivable One.