This essay provides an analysis of the creation of jus cogens. The analysis makes intelligible the definition of jus cogens provided in Art. 53 of the 1969 Vienna Convention on the Law of Treaties. It has been said repeatedly about this definition that it is circular. If a jus cogens status is conferred on a rule of law because the international community of states accepts and recognizes this rule as non-derogable and modifiable only by the creation of a new norm of jus cogens, then the definition assumes what remains to be established: the creation of jus cogens. As shown in this essay, this criticism builds on wrongful assumptions. It assumes that Art. 53 explains the creation of jus cogens, which it does not; it explains only its existence. A full explanation of the creation of jus cogens requires further elaboration. According to the proposition argued in this essay, jus cogens obligations derive from the usual processes creating ordinary customary international law.