The text mentions writing biographies of both saints and worldly figures. Why is one considered spiritually superior to the other?

The preface in Chapter 0 draws a clear distinction between writing about worldly figures and writing about saints. Writing biographies of great people like politicians, warriors, or writers is considered a worldly form of Guru service. While it can be a form of public service, it is ultimately limited by space and time and rooted in self-interest, therefore it does not yield spiritual fruits. In contrast, writing the biographies of saints is a form of Guru service that does yield spiritual fruits, and writing about one's own Sadguru is considered the highest form of this service, leading toward the ultimate spiritual goal.