How does the introduction of the Shri Sai Satcharita describe the Sadguru, and how does this relate to the book's purpose of achieving unity with the divine?

Chapter 0's introduction begins with powerful salutations, describing the Sadguru as the "bliss of Brahman," the "personification of knowledge," and "beyond dualities." He is portrayed as the goal of 'That Thou Art', eternal, pure, and the witness of all intelligence. This sublime description of the Guru directly relates to the book's ultimate purpose, as explained in the preface. The text is presented as a means for devotees to perform a "sacrifice of knowledge," which, when done with faith, allows the seeker to eventually become one with the very same Shri Sai-Paramatma after death.