How does the story of Damu Anna in Chapter 25 illustrate the concept of "one-pointed devotion" and Sai Baba's role as an "Ocean of Mercy"?

Chapter 25 uses Damu Anna's story to exemplify the relationship between a devotee's faith and the Guru's grace. The chapter emphasizes that Sai desires "one-pointed devotion," and Damu Anna's unwavering commitment, shown through his long-standing vow to provide a flag for the Ram Navami festival, is a perfect illustration of this principle. In response to this steadfast faith, Sai embodies the role of an "Ocean of Mercy." The text demonstrates this by recounting how Sai not only warded off Damu Anna's misfortune of being childless by blessing him with sons but also shows a general readiness to protect all His devotees. The chapter presents this narrative to prove how the "Guru-Mother is an 'Ocean of Mercy,'" removing suffering for those with unwavering faith.