Based on the introductory verses of Chapter 18, what are some of the key attributes of the Sadguru?

The opening of Chapter 18 offers a series of powerful salutations that describe the supreme nature of the Sadguru. He is hailed as the 'supreme Eternal one' and the 'Truth of Brahman.' The chapter praises the Guru as the one who, through direct experience, reveals the illusory nature of the world, making him the 'Ruler of Maya.' Additionally, the Sadguru is described as being 'Beginningless and Endless,' beyond duality, and 'without blemish.' Chapter 18 concludes these praises by identifying the Guru as the sole teacher of the knowledge of the Self, underscoring his ultimate spiritual authority.