How did Dev finally learn the truth about Baba's presence at his ceremony, and what was his emotional response?

Dev learned the truth after his friend Jog communicated the entire account of Baba's explanation in a detailed letter. Upon reading Jog's letter, Dev had a profound emotional reaction. As described in chapter 40, Dev's eyes "overflowed with a surge of love." He was overcome with remorse for his lack of faith, exclaiming, "Shame, shame! I blamed Sai in vain!" He felt very dejected in his mind, recognizing the folly of his own pride and knowledge compared to the immense greatness of Sai Baba, and he deeply regretted not being able to recognize his master.