 Daoist philosophers typically express their doubts about first-order human dao (paradigmatically Confucian and Mohist dao) by considering them in relation to natural dao and/or great dao (the actual dao). This plays on the tendency of rival schools of ancient Chinese moralists to treat tiannature:sky as the authority for their favored human daos. Mature Daoist analysis centers on the insight that while human daos are normative, neither the natural nor the actual dao are. Natural dao and Great dao are  “constant”  while human dao are inherently changeable and subject to interpretation. This insight is most famously expressed in the first line of the Daode Jing “daoguides that can daoguide are not constant daoguides.”