  The Laozi makes use of the concept of ziran, literally what is “self (zi) so (ran),” to describe the workings of Dao. As an abstract concept, ziran gives no specific information, except to say that Dao is not derived from or “modeled” (fa) after anything (ch. 25). However, since “heaven and earth”—interpreted as nature in most modern studies—are said to be born of Dao and come to be in virtue of their de, the Laozi is in effect saying that the ways of nature reflect the function of Dao.