What is the central message regarding faith and medicine conveyed through the story in Chapter 34?

The central message of Chapter 34, conveyed through the story of the doctor's nephew, is the supremacy of faith and the Guru's grace over the limitations of worldly knowledge and medicine. The chapter deliberately highlights that the boy's uncle was a degree-holding doctor and that expert surgeons and all known native and foreign treatments were tried and had failed. This failure of the medical establishment is contrasted with the simple, faith-based solution offered by Sai Baba. By having them smear Udi on the wound, Baba demonstrates that true healing comes from a higher power and that when all human efforts are exhausted, surrendering to a Sadguru can bring about miraculous results that science cannot explain.