The preface distinguishes between different types of service. Can you compare worldly service with spiritual service and explain why writing a Sadguru's biography is considered the most effective form?

The preface, as presented in Chapter 0, draws a clear distinction between worldly and spiritual service. Writing biographies of worldly figures like politicians is considered worldly service; its fruits are temporary and limited by space and time because it is often rooted in self-interest. Writing biographies of many saints is a spiritual service, but it's considered partial. The text posits that the best and most certain service for attaining salvation is to write the biography of one's own Sadguru. This act, when done with pure faith and devotion and followed by regular study and recitation, is a profound form of service that yields the ultimate spiritual fruit without interfering with one's worldly responsibilities.