The text says 'no one has unmixed happiness.' How does the story of Ratanji illustrate this philosophical point?

The story of Ratanji serves as a prime example of the principle that no one experiences pure, unadulterated happiness. Chapter 14 describes him as a man who had everything the world could offer: vast wealth, property, a good reputation, and a generous spirit. To an outside observer, he was the picture of success. Yet, the text reveals that 'the crocodile of a difficult inner worry always surrounded the merchant.' This worry was his lack of a son, which caused him constant sadness and made food and drink tasteless. His situation perfectly illustrates the book's point about the 'divine plan' ensuring everyone has some form of nagging worry, preventing arrogance and reminding them of life's complexities.