China's Drama Theory Monographs is the earliest systematic drama monograph in China. Written by Li Yu in Qing Dynasty. It was published in the 10th year of Kangxi (167 1) and later included in The Complete Works of Li Wengjia. Casual Love includes eight parts: lyrics, exercises, volume, living room, playing with utensils, drinking, planting and caring for the elderly. The content is more complicated, including drama theory, health preservation and garden architecture. However, in the theory of traditional Chinese opera, only the part of lyrics, the part of exercises and the part of sound volume are involved, so later generations cut out different articles and compiled them into Qu Hua by Li Liweng.