Come in, master of Chinese studies: four dreams in one's life, but where did the Peony Pavilion come from?

The Peony Pavilion, The Story of Purple Hairpin, The Story of Handan and The Story of Conan written by Tang Xianzu are all called "Four Dreams in Linchuan", but this sentence "I have dreamed four dreams all my life, and the only one I am proud of is peony" doesn't seem to be in the book. It's a sentence he said after writing four books. Because of the four dreams, the peony pavilion is the most famous one, so he said, "I have four dreams in my life, but I am proud of peony."