How did Sai Baba demonstrate his knowledge of Saheb Dixit's private meditation?

In a remarkable incident described in Chapter 4, Saheb Dixit experienced a vision of Vitthal during his private morning meditation. When he later went for Baba's Darshan, Baba surprised him by asking, "Vitthal Patil had come, right? Did you meet him?" Baba further advised Dixit to "nail him down and make him steady," warning that Vitthal would escape if his attention wavered. This was confirmed when a seller arrived with pictures of Vitthal, one of which perfectly matched the form Dixit had seen in his vision, causing Dixit to marvel at Baba's words.