The text mentions that a Sadguru takes two types of service through books. Can you elaborate on these two methods?

The text outlines two distinct ways a Sadguru accepts service from devotees through literary works. As stated in Chapter 0, the first method is when the Sadguru creates great spiritual works himself, with examples cited being Shri Dnyaneshwari, Shri Nath Bhagavata, or Shri Dasbodh. The second method involves the Sadguru having his biographies written by his devotees. In this case, the Guru accepts service from both the writer and the wider congregation of devotees who engage with the biography through study and Parayans (devotional readings). The text highlights Shri Sai Satcharita, written by Annasaheb Dabholkar about Sai Baba, as a prime example of this second form of service, where the biography becomes a central text for devotion and community practice.