Why does the author of Sai Satcharitra invoke Goddess Saraswati in Chapter 1, and how is she also identified with Sai?

The author invokes Goddess Saraswati because she is the Goddess of Speech and the Mother of the Universe and Vedas. As Chapter 1 states, the author questions how the book could possibly be written without her grace, viewing her as essential for any literary achievement. The text describes her holding the Brahma-veena and riding a swan, requesting her to make the author an instrument for narrating Sai's life. Following this invocation, the chapter draws a parallel, proclaiming that 'Sai himself is Goddess Saraswati, holding the Omkara-veena in hand, singing his own life story for the salvation of his devotees,' thus equating Sai with the very source of knowledge and expression.