What specific qualities of Sai Baba's Udi are highlighted in the story of the boy with the bone-cyst?

The story of the boy with the bone-cyst in Chapter 34 serves as a primary illustration of the 'greatness of Udi.' The narrative emphasizes that Udi possesses the power to cure 'incurable diseases.' The bone-cyst, or Hadyavran, was a 'terrible disease' that could not be cured by any remedy, exhausting even expert surgeons. The key quality highlighted is Udi's ability to succeed where all other efforts have failed, showing its divine and limitless potency. The chapter states, 'Smearing it with the Udi from Sai’s hand completely uprooted the pain.' This demonstrates that Udi is not merely a physical substance but a conduit for Sai Baba's grace and protective power, capable of resolving calamities and providing a way 'to cross over' immense suffering when one seeks refuge in Him.