In "The Variation of Chinese Literature and the Formation of World Literature" Shunqing Cao and Lu Zhai discuss how Chinese works of literature entered other countries' literary circles through variation, and became an essential part of world literature. Both ancient Chinese literature and contemporary Chinese literature have undergone textual circulation, language translation and cultural filtering before becoming part of world literature, all of which are the reasons why literary variation occurs. According to Cao and Zhai, the occurrence of variation is a key factor for Chinese literature to become world literature, and an important foundation for the formation of world literature. A country's literature absorbs the characteristics of other countries' literature through variation, thus adapting to the cultural background and reading habits of other countries' readers in terms of language and style, in order to enter the world literature market. Variation may lead to a certain loss of nationality in literary works, and result in significant differences from the original texts. However, the formation of world literature does not come at the cost of eliminating nationality; variation facilitates the formation of world literature.