Wan Fang, 68, a Chinese playwright, who is the daughter of Cao Yu, said: "I watched my father's Thunderstorm many times at the Beijing People's Art Theater, where my father was one of the theater's founding members and its first president. I was so scared that I started to cry when I first heard the noise of the thunderstorm emanating from the stage. My father started to write the play when he was about 19. I am also a writer but writing such a great work like Thunderstorm at merely 24 is beyond my imagination," she adds.

Wan Fang's plays, including Winter Journey and New Wilderness, were also staged at Poly Theater on July 31. During December, her works will also be adapted, including her latest work, Thunderstorm II, a sequel to Thunderstorm. It will focus on the characters' choices at the end of Thunderstorm, how they recall the night and the people they would later become.

She says the characters in Thunderstorm are memorable and had distinctive personalities. She wondered what future the characters would have after that fateful night, where some of them uncover bitter truths and others lose their minds.

"Many people ask me about the definition of 'classic' since many of my father's works are considered as classic. My answer is that when a play is adapted and staged again and again and audiences from different generations share the emotions in it, it becomes a classic naturally," she says. "The key of creating a classic work is the writer's sincerity."

Cao was a sincere man and he was a keen observer. As Wan Fang recalls, her father liked to walk around after dinner. One day, when Wan Fang walked with him, Cao Yu suddenly stopped and said: "Being young is beautiful," while pointing at a young couple on the street.

"He told me that writing originated from subtle and careful observation of real life. I felt lucky to be his daughter as I learned a lot from him both through his writing and personality," she adds.