What does the story of Radhabai Deshmukh's fast illustrate about seeking instruction from Sai Baba?

The story of Radhabai Deshmukh, detailed in Chapter 18, illustrates that seeking instruction from Sai Baba could involve a profound test of one's devotion. Radhabai, an elderly woman, had a firm resolve to receive a secret mantra directly from Baba's lips. To achieve this, she undertook a 'dharna' or fasting protest, renouncing all food and water for three days and nights. The narrative suggests that Baba sometimes tests a person to the limit, putting their devotion and love to the test before imparting guidance. Her extreme austerity, to the point of fasting unto death, shows the intense lengths a devotee might go to and how Baba would test the sincerity of their resolve.