How does the introduction to the Shri Sai Satcharita define the nature and significance of a Sadguru?

The introduction to the Shri Sai Satcharita, located in Chapter 0, begins with powerful salutations that define the profound nature of a Sadguru. It presents two traditional verses to articulate this significance. The first verse equates the Guru with the divine trinity, stating, 'The Guru is Brahma, the Guru is Vishnu, the Guru is Lord Maheshwara; the Guru is the manifest Supreme Brahman.' The second verse, as cited in Chapter 0, delves deeper, describing the Sadguru as the embodiment of Brahman's bliss, the bestower of supreme happiness, the personification of pure knowledge, beyond all dualities, eternal, immovable, and the witness of all intelligence, thus establishing the Sadguru as the ultimate spiritual guide.