Sovereignty, though its meanings have varied across history, also has a core meaning, supreme authority within a territory. It is a modern notion of political authority. Historical variants can be understood along three dimensions — the holder of sovereignty, the absoluteness of sovereignty, and the internal and external dimensions of sovereignty. The state is the political institution in which sovereignty is embodied. An assemblage of states forms a sovereign states system. The history of sovereignty can be understood through two broad movements, manifested in both practical institutions and political thought. The first is the development of a system of sovereign states, culminating at the Peace of Westphalia in 1648. Contemporaneously, sovereignty became prominent in political thought through the writings of Machiavelli, Luther, Bodin, and Hobbes. The second movement is the circumscription of the sovereign state, which began in practice after World War II and has since continued through European integration and the growth and strengthening of laws and practices to protect human rights. The most prominent corresponding political thought occurs in the writings of critics of sovereignty like Bertrand de Jouvenel and Jacques Maritain.