How does the author of the preface justify the creation of a new, detailed biography like the Shri Sai Satcharita, and what benefits does it provide?

The preface in Chapter 0 justifies the need for a detailed work like the Shri Sai Satcharita by pointing out that existing biographies of saints, such as those in Shri Dasganu Maharaj's works, are often too brief for a dedicated Parayan. By creating a detailed poetic Guru biography, the writer performs a great service to the Guru. Simultaneously, as Chapter 0 elaborates, when other devotees study this work, the writer gains the merit of serving humanity (Jan-Janardan), and those devotees in turn are helped to achieve the purpose of their lives, making it a spiritually beneficial endeavor for all.