According to Chapter 48, what distinguishes a true Sadguru from other spiritual teachers who possess only verbal knowledge?

Chapter 48 draws a clear line between a true Sadguru and other teachers. It specifies that individuals who simply study the Vedas, explain Vedanta, or please audiences with talks on Brahman are not considered Sadgurus by the wise. The chapter describes those with vast verbal knowledge but no self-experience as being "verbally hollow." The essential differentiator, as stated in Chapter 48, is direct experience. A Sadguru is defined as one who not only has complete verbal knowledge but is also a giver of direct, full experience, which is the sole authority to enlighten disciples. Without this direct experience, one should never be called a Sadguru.