How did Sai Baba demonstrate his foreknowledge of Damu Anna's letter before it was read to him?

The narrative in Chapter 25 illustrates Sai Baba's apparent omniscience. When Madhavrao (Shama) placed Damu Anna's letter at Baba's feet, Baba immediately began speaking about its contents without it being read. He said, "It seems he is trying to touch the sky! He doesn't want what God gives." Shama was astonished and confirmed that Baba's words were the exact meaning of the letter. Shama even marveled at how Baba knows the inner intent of devotees. Despite this, Baba playfully feigned ignorance, saying "I just speak whatever comes to my mind," and instructed Shama to read the letter aloud anyway.