Yijing (意境) is a central concept in Chinese poetry although it is not easily translated. It has been defined as "the fusion between “emotion” (情) and “scenery” (景)" and Yanfang Tang writes that emotion and scene "constitute two basic elements in the construction and realization of yi jing. All literary discussions about yi jing in traditional Chinese criticism revolve around the relation and interplay of these two essential elements." Tang also states that the technique of yijing is "to express human emotion" "through the depiction of scene".