What's the story behind Sai Baba grinding wheat, and what was the true purpose of this act?

In a perplexing event described in Chapter 1, Sai Baba, who lived on alms and had no possessions, suddenly began grinding wheat in the mosque. While villagers watched in wonder, four women took over, singing his praises but secretly hoping to take the flour for themselves. After they finished, Baba became angry when they tried to divide the flour and ordered them to throw it on the village boundary. The true purpose, as revealed later in Chapter 1, was that the wheat symbolized a cholera epidemic. By grinding it and having the 'flour' cast out, Baba spiritually drove the disease away from the village, and the epidemic subsequently receded.