According to the preface, what distinguishes the Shri Sai Satcharita from other poetic books and ensures its lasting impact?

The preface, as detailed in Chapter 0, classifies poetic books into three types: natural, graceful (Prasadik), and artificial. It argues that a book written solely on the strength of scholarship and intelligence, while potentially good, will not last eternally because it lacks inspiration, grace, or the quality of a divine gift. The Shri Sai Satcharita is identified as a 'grace-filled (Prasad-janya) book.' The text asserts that without Guru's grace, creating such a work is difficult, regardless of one's scholarship. It is this quality of grace that ensures the book will leave a deep impression on seekers, inspire faith, and be studied daily through Parayans and Saptahs.