How does a Sadguru accept service from devotees through literature, and what role do devotees play in this process?

According to the preface in Chapter 0, a Sadguru accepts service from his devotees through books in two primary ways. The first is when the Guru creates monumental works themselves, such as the Shri Dnyaneshwari. The second method is by having his biographies written by his devotees. The service is then rendered through the collective study and devotional readings (Parayans) of these biographies by both the writer and the wider congregation of devotees. In this way, devotees actively participate by studying the texts, which allows them to serve the Guru and also helps them achieve the purpose of their own lives.