Can you explain the philosophical concept of the four stages of speech (Para, Pashyanti, Madhyama, Vaikhari) as referenced in Chapter 49 in the context of praising the Sadguru?

Chapter 49 uses the concept of the four stages of speech to illustrate the impossibility of describing the Sadguru's true nature. It states that the Sadguru's greatness is beyond even the 'Para' or transcendental speech, from which it returns defeated. Consequently, the intermediate stages of 'Pashyanti' and 'Madhyama' have no access either. This leads to the conclusion that the fourth stage, 'Vaikhari' or the spoken word, is utterly incapable of comprehending the Sadguru's inconceivable art. This reference, as detailed in Chapter 49, serves to underscore the profound and inexpressible reality of Sai, which can only be approached through grace and surrender, not intellectual or verbal constructs.