Based on the text of Chapter 48, what distinguishes a true Sadguru from someone who only has extensive verbal or scriptural knowledge?

According to the teachings in Chapter 48, the crucial distinction lies in direct experience versus mere verbal knowledge. The chapter explains that individuals who can explain the Vedas, Shastras, or Vedanta, or who give pleasing talks about Brahman, are not necessarily Sadgurus. This knowledge is described as "verbally hollow" if it lacks the foundation of self-experience. As Chapter 48 clarifies, a true Sadguru is one who is a "giver of direct, full experience" and has the authority to enlighten disciples precisely because they possess this realized wisdom, not just theoretical principles.