Who thinks that China's literary tradition "begins with sadness and ends with joy?"

This sentence comes from Wang Guowei's Annotations. In this book, he thinks that the spirit of China's traditional opera novels, "There is no such cheerful color along the way: it begins with sadness and finally happiness, ends with separation and finally unity, and ends with difficulty and finally constancy", which means that the spirit of China's traditional opera novels often begins with tragedy, ends with comedy, ends with reunion, and ends with poverty and prosperity, which is often called "happy reunion".