From a spiritual perspective, what is the dual role of a detailed Guru biography for both the author and the readers, as outlined in the preface?

The preface in Chapter 0 explains the profound dual role of a detailed Guru biography. For the writer, the act of composing the biography is a direct form of 'Guru service.' For the readers, the biography serves as a vehicle for their own spiritual progress. As other devotees study and perform Parayans (devotional readings) of the text, they work towards achieving the purpose of their lives. This dynamic means the writer also gains the merit of public service and serving God in humanity, creating a powerful spiritual feedback loop between the author, the Guru, and the congregation of devotees.