According to the preface, what distinguishes a 'graceful' spiritual book from an 'artificial' one, and which category does Shri Sai Satcharita fall into?

The preface discussed in Chapter 0 outlines three types of poetic books: natural, graceful (Prasadik), and artificial. An artificial book, written solely from intellect and scholarship, may be good but will not endure eternally or possess inspiration and divine gift. A graceful book, on the other hand, possesses these qualities, which are essential to leave an impression on seekers and build their faith. The Shri Sai Satcharita is definitively categorized as a 'grace-filled (Prasad-janya) book.' Its creation is attributed not to the author's scholarship alone, but to the Guru's grace that fell upon him.