 In the Essays on the Law of Nature, Locke writes that “all the requisites of a law are found in natural law” (Locke 1663–4, 82). But, what, for Locke, is required for something to be a law? Locke takes stock of what constitutes law in order to establish the legalistic framework for morality: First, law must be founded on the will of a superior. Second, it must perform the function of establishing rules of behavior. Third, it must be binding on humans, since there is a duty of compliance owed to the superior authority that institutes the laws (Locke 1663–4, 83). Natural law is rightly called law because it satisfies these conditions. For Locke, the concept of morality is best understood by reference to a law-like authority structure, for without this, he argues, moral rules would be indistinguishable from social conventions. In one his later essays, “Of Ethic in General”, Locke writes