Based on the story of the doctor's nephew, what does Chapter 34 reveal about the nature and power of Sai's Udi?

Chapter 34 uses the story of the doctor's nephew to illustrate the divine and supreme power of Sai Baba's Udi. It is portrayed not as a mere ash, but as a potent symbol of Sai's grace that transcends the limits of medical science. The chapter emphasizes that Udi succeeded where expert physicians, surgeons, and both native and foreign treatments had failed against a 'most difficult and extraordinary malady.' This demonstrates that Udi's efficacy is spiritual, capable of completely uprooting incurable diseases. Baba's act of giving the Udi, combined with his words of assurance, signifies that its power is activated by faith in the Sadguru, making it a tangible form of his protection and a final, unfailing resort for devotees in distress.