What is the primary topic of Chapter 48 of the Sai Satcharitra, and how does it define a Sadguru?

Chapter 48 primarily addresses a listener's question about whether Shri Sai is a Guru or a Sadguru by detailing the characteristics of a true Sadguru. The chapter explains that a Sadguru is not defined by knowledge of the Vedas or Shastras, nor by performing rituals like Pranayama. Instead, as Chapter 48 clarifies, a Sadguru is someone who possesses direct, full self-experience and has the authority to enlighten disciples. This individual is free from ego, sees the disciple as Supreme Brahman, and holds a fatherly love for them, never desiring service or livelihood in return. This definition is provided to help the reader find these signs at the feet of Shri Sai.