The text describes a man who was initially cynical about Gurus. What specific event caused him to question their power against destiny?

The author, who describes himself in Chapter 2 as initially cynical, critical, and prone to argumentation, had his doubts about the power of Gurus solidified by a personal tragedy affecting a close friend. His friend's only son, who was healthy and virtuous, was suddenly stricken with a fever in Lonavala. Despite trying all human remedies and even having the boy's own Guru sit by his side, the son ultimately passed away. Witnessing this, the author's mind became very restless, and he explicitly questioned the benefit of a Guru's company, wondering what they could possibly do against the force of Karma. This event made him conclude that destiny is irresistible and caused him to initially abandon his plan to go to Shirdi.