How does the act of writing and studying a Sadguru's biography lead to enlightenment, and what qualities are required from the devotee?

The Preface (Chapter 0) outlines that the most certain service for attaining salvation is to write the biography of one's Sadguru and then regularly study it through Parayans and Saptahs. This path to enlightenment requires specific qualities from the devotee: a firm resolve, a pure heart, excellent faith, selfless love, and unwavering devotion. By surrendering at the Guru's feet and performing this service without ego, as Dnyaneshwar Maharaj advises, the devotee's heart becomes enlightened and their doubts are dispelled. This dedicated practice is considered the highest form of Guru service.