The text claims writing a biography of one's own Sadguru is the 'best' service. Does this mean that writing biographies of other saints is considered a negative or spiritually detrimental act according to the author?

The preface in Chapter 0 presents a nuanced view. While it describes writing the biography of one's own Sadguru as the 'best and most certain service' for attaining salvation, it does not frame the writing of other saints' biographies as a negative or spiritually detrimental act. Instead, it characterizes that service as 'one-sided or partial,' noting that it is 'difficult, or rather impossible, to attain the ultimate spiritual goal' through that method alone. The author emphasizes a hierarchy of effectiveness for spiritual goals, rather than labeling other forms of service as inherently bad.