According to the first chapter, why is Goddess Saraswati invoked, and how is Sai Baba identified with her?

The first chapter of the Sai Satcharitra explains that Goddess Saraswati, the daughter of Brahma, is invoked for her grace in creating literature. The author questions how the book could be written without the favor of the Goddess of Speech and Mother of the World, who holds the Brahma-veena and rides a swan. She is seen as a river of knowledge and virtues. Chapter 1 beautifully equates Sai Baba with her, stating that Sai himself is Goddess Saraswati. In this form, he holds the Omkara-veena and sings his own life story for the ultimate salvation of his devoted followers.