What inspired devotees to document the lives of Gurus like Sai Baba, according to the preface?

The inspiration to document a Guru's life stems from it being a superior form of service, a tradition described as ancient and mentioned in the Narada Purana. As Chapter 0 clarifies, a Sadguru accepts service from devotees through the creation of their biographies. This act is not only a service to the Guru by the writer but also benefits other devotees who study the work. By performing Parayans of a detailed biography, the writer gains the merit of serving God in humanity, and other devotees are helped to achieve the purpose of their lives, making it a profoundly meaningful endeavor.