From the perspective of the text's preface, what distinguishes a 'grace-filled' spiritual work from one based merely on scholarship?

The preface in chapter 0 outlines a clear hierarchy for poetic books, distinguishing between 'natural,' 'graceful,' and 'artificial' works. A book based on scholarship alone is deemed 'artificial' and lacks eternal-lasting power. A truly impactful spiritual book, one that inspires faith and devotion, must be 'grace-filled' (Prasadik). This means it possesses inspiration and is a divine gift, qualities that are difficult to attain without a Guru's grace. The Shri Sai Satcharita is presented as an example of a 'grace-filled (Prasad-janya) book,' which is why it is expected to be embraced and studied daily by any seeker-devotee.