Mookaa Baba was a resident of Nagpur, where the Jessawalas lived when they first came to Baba. He was called Mookaa Baba by the townspeople because he would not talk to them. He was a tall and very imposing figure, and he went about stark naked.
He would come to Gaimai's house and once there he would talk to the family, giving them instructions on how to ready a bath for him, to rub him with ghee (clarified butter) then make his food, etc. Manu once asked him, "Baba, the townspeople call you Mookaa Baba, they think you can't or don't speak, but you talk to us, why?" He replied, "You are of my family, and I am happy when I am with you all, that is why I talk to you."
Now Behramshaw Papa (Papa Jessawala) didn't like Mookaa Baba coming to their house, treating it as his own and 'lording' it over the family and servants. He complained non-stop about this naked and 'dirty' fellow, and even told Mookaa Baba to go away. In reply he was told, "This is my house, and I will come here whenever I want." Papa always told Gaimai that she was being bamboozled, but Gaimai insisted that this was a spiritually advanced soul. However, an incident convinced Papa that he was wrong. This is what happened.
One day Mookaa Baba was as usual there, and water was being made hot for his bath, when Papa rushed out on his way to work and called to Manu for a cup of coffee. Now, it was a hot summer day, and the milk had turned. Manu went off to make the coffee, when Mookaa Baba laconically said to Papa, "Old man, what are you ordering that girl to make coffee for? Don't you know that the milk has split? There will be no coffee." So when Manu came back nervously to tell Papa there could be no coffee, he asked her if it was because the milk had split. She said, "Yes, Papa." After this Papa made no further comments about the visits.
After a while Beloved Baba came to visit, and on seeing Him, Mookaa Baba said, "He and I are one." Mookaa Baba continued to visit while the family lived in Nagpur. He would come for his meals to the house and tell them that when he ate, Baba was being fed, because he was one with Baba. Years later, when Eruch was writing God Speaks, the subject came up and Baba confirmed that Mookaa Baba was a realised soul.