 As a proper term, Xuanxue gained currency during the fifth century C.E. It named a branch of learning that formed a part of the curriculum of the imperial academy. The subject matter of Xuanxue in this formal sense centered on the Yijing (Classic of Changes), the Laozi, the Zhuangzi, and selected commentaries on them. These three classical texts were seen to hold deep insight into the cosmos and the human condition, and were referred to collectively as the “Three (Great Works on the) Profound” (sanxuan). They articulated their vision of “grand harmony” and “great peace” through the concept of Dao, which demanded explication. It is precisely the goal of Xuanxue, then, to bring to light the nature and function of Dao, which may appear dark or impenetrable.