 Until the eighteenth century, it was assumed that human beings are unequal by nature. This postulate collapsed with the advent of the idea of natural right, which assumed a natural order in which all human beings were equal. Against Plato and Aristotle, the classical formula for justice according to which an action is just when it offers each individual his or her due took on a substantively egalitarian meaning in the course of time: everyone deserved the same dignity and respect. This is now the widely held conception of substantive, universal, moral equality. It developed among the Stoics, who emphasized the natural equality of all rational beings, and in early New Testament Christianity, which envisioned that all humans were equal before God, although this principle was not always adhered to in the later history of the church. This important idea was also taken up both in the Talmud and in Islam, where it was grounded in both Greek and Hebraic elements. In the modern period, starting in the seventeenth century, the dominant idea was of natural equality in the tradition of natural law and social contract theory. Hobbes (1651) postulated that in their natural condition, individuals possess equal rights, because over time they have the same capacity to do each other harm. Locke (1690) argued that all human beings have the same natural right to both (self-)ownership and freedom. Rousseau (1755) declared social inequality to be the result of a decline from the natural equality that characterized our harmonious state of nature, a decline catalyzed by the human urge for perfection, property and possessions (Dahrendorf 1962). For Rousseau (1755, 1762), the resulting inequality and rule of violence can only be overcome by binding individual subjectivity to a common civil existence and popular sovereignty. In Kant’s moral philosophy (1785), the categorical imperative formulates the equality postulate of universal human worth. His transcendental and philosophical reflections on autonomy and self-legislation lead to a recognition of the same freedom for all rational beings as the sole principle of human rights (Kant 1797, p. 230). Such Enlightenment ideas stimulated the great modern social movements and revolutions, and were taken up in modern constitutions and declarations of human rights. During the French Revolution, equality, along with freedom and fraternity, became a basis of the Déclaration des droits de l’homme et du citoyen of 1789.