Any EU constitution tomorrow will need to embody basic European ethical values. Yet the identity of such values and their sources remain strongly controversial. Peter McCormick retrieves from cultural origins of some major European values a basic ethical value of a measured and critically reasoned restraint in all things. At the same time he argues that this originary ethical value entails a renewed understanding of political, social, and individual sovereignties no longer as almost absolute but as necessarily limited. The rewards for polities of fully assuming such a basic ethical value turn out to include the ineluctable necessity for the rule of law, the constitutionalisation of social pluralisms, and the entrenchment of personal dignity.