What is Guru service, and what are some different types mentioned in the preface?

Guru service is a path to attaining spiritual knowledge. As Chapter 0 explains, drawing from the teachings of Lord Samarth Sadguru Dnyaneshwar Maharaj, one should serve the saints with their entire being. The text describes several forms of this service. One type is writing the biographies of great worldly figures like politicians or historians, which is considered a worldly service with temporary and limited fruit. A more spiritually beneficial form, as detailed in Chapter 0, is writing the biographies of saints. This type of service is considered to yield spiritual fruits because it is less likely to be rooted in self-interest and is focused on spiritual ideals rather than worldly achievements.