Started with the image of chaos, this paper probes into the dual structure of chaos in the "Laozi". The first structure is ontology; it shows the curious logic of the well-known saying "Existence and non-existence are from the same origin but have different names." The other is ethics, which demonstrates the strange sameness and difference of chaos and order. This paper focuses on Laozi's ethical concern, disclosing that the "xuan-de" 'profound virtue' has the tender power that can cure the dual structure and can particularly be compared to with the virtue of water in the phrase "The best virtue is like water." "Primitive ethic" is what this paper calls this tender care that criticizes and cures the dual regulation ethic and tolerates others in the "Laozi". The balanced relation between chaos and order in Daoism is reflected in the relation between the primitive ethic and the regulation ethic; in other words, primitive ethic contradicts regulation ethic but also interacts with it. Hence, the "Laozi" and the "Zhuangzi" are mostly the same but different in some ways. The "Laozi" emphasizes differences more than sameness whereas the "Zhuangzi" otherwise.