How does a Sadguru accept service from devotees through books, as described in the text?

The text in Chapter 0 explains that a Sadguru can take two types of service from devotees through books. The first way is by creating great spiritual works themselves, with examples like Shri Dnyaneshwari or Shri Dasbodh being cited. The second method is by having their biographies written by their devotees. In this second scenario, the Sadguru accepts service not only from the writer but also from the entire congregation of devotees who engage with the biography through study and the performance of Parayans, thereby helping them achieve the purpose of their lives.