What does the text identify as Guru service, and what are some different types mentioned?

Guru service encompasses infinite paths and means. Drawing from the wisdom of Dnyaneshwar Maharaj, Chapter 0 explains that serving saints with one's entire being is a way to gain knowledge. The text also describes writing biographies as a form of Guru service. This can be worldly, like writing about politicians or writers, but this service is limited by time and self-interest and does not yield spiritual fruit. A higher form mentioned in Chapter 0 is writing the biographies of saints, which provides spiritual benefits, though it is still considered a partial form of service.