Can you explain the description of Sai as the Supreme Divinity in Chapter 4, including the reference to 'Neti-Neti'?

In Chapter 4, Sai is equated with the highest divinity, described as the Inner Self and the Supreme God who brings joy to the world. He is identified as the Guru and the joy-giving Shankar. This supreme being is eternal, non-dual, and beyond all limitations of place, time, or object. The chapter emphasizes the inadequacy of language to describe Him, stating that the four levels of speech—Para, Pashyanti, Madhyama, and Vaikhari—get tired in the attempt. Even the Vedas, in their cleverness, failed to define Him and ultimately resorted to the expression 'Neti-Neti,' which means 'Not this, Not this,' signifying that the divine is beyond all worldly descriptions.