Why is Goddess Saraswati invoked in Chapter 1, and how is she identified with Sai?

Goddess Saraswati is invoked in Chapter 1 because she is the 'Goddess of Speech' and 'Mother of the World', without whose grace literature cannot be achieved. She is described as holding the 'Brahma-veena' and riding a swan. The author pleads for her mercy to become an instrument for sharing Sai's life story. Chapter 1 beautifully equates Sai with her by stating, 'Sai himself is Goddess Saraswati, holding the Omkara-veena in hand, singing his own life story for the salvation of his devotees.' This implies that Sai is the ultimate source and narrator of his own divine biography.