From a Sadguru's perspective, what are the two methods through which they receive service from devotees via books?

As detailed in Chapter 0, a Sadguru accepts service from devotees through literary works in two distinct manners. The first is by creating great spiritual works themselves, such as the cited examples of 'Shri Dnyaneshwari' or 'Shri Dasbodh'. The second method is by having their biographies written through their devotees. In this case, the Sadguru accepts service in the form of study and Parayans performed by both the author of the biography and the broader congregation of devotees who read and study the work, thereby creating a community of practice around their life and teachings.