How do Sadgurus receive service from their followers through books?

According to the provided text, a Sadguru accepts service from devotees through books in two distinct ways. The first is when the Sadguru creates great works themselves, like Shri Dnyaneshwari. The second method, as detailed in Chapter 0, is when the Sadguru has their biographies written by devotees. In this case, the writer performs a service by authoring the text, and the wider community of devotees performs service by studying it and conducting devotional readings, known as Parayans. This allows the writer and the readers to achieve the purpose of their lives through this engagement.