Can you tell me about the author's personal experience with another saint before he met Sai Baba, as mentioned in Chapter 21?

Certainly. In Chapter 21, the author, Hemadpant, recounts a personal story from his time as a Magistrate in Bandra. He mentions a famous Siddha named Pir Maulana, who was revered by people of all faiths. The Siddha's servant, Inus, persistently urged Hemadpant to come for his vision. However, Hemadpant admits that his own pride and what he calls 'ill-luck' prevented him from going. He questioned why he should be pressured by others and lose his prestige. This chapter reveals that he never went for the vision, using this experience to illustrate that one's fortune must dawn to encounter Saints, a lesson he learned before his unbreakable bond with Shirdi was formed.