What is the origin and purpose of the book 'Sai Leela' as described in the Satcharitra?

According to Chapter 52, the book "Sai Leela" was written to remember the experiences that Sai Baba gave to His devotees while He was in His body. The chapter explains that the inspiration for the book came after He departed to His own abode. It is noted that Sai Himself chose Hemadpant to be the author, holding his hand through the process even though Hemadpant felt he was devoid of specialized knowledge. The purpose of this supremely holy text is to provide enlightenment for this world and the next by sharing the stories of Sai's true character.