The term refers to a Daoist way of breaking away from the difference and opposition between one’s self and the universe. It comes from the book Zhuangzi, which elaborates its meaning in a dialogue between Confucius (551-479 BC) and Yan Hui (521-481 BC). In Zhuangzi’s (369?-286 BC) view, status and etiquette norms in the human world caused divisions and antagonisms and hence created constraints on people. One should forget status and norms and furthermore forget one’s own physical existence and intellect to cast off the differences between one’s self and the universe and thus be free from the constraints and influence of external factors.

Yan Hui said, “I forget.” Startled, Confucius asked, “What do you mean by forgetting?” Yan Hui answered, “Pay no attention to my body and give up what I hear and see, leave the physical form, get rid of what occupies my mind, and become one with the universe. This is what I call forgetting the difference and opposition between myself and the universe.” (Zhuangzi)