rulers . The plan, which was presented to the Congress of Utrecht (1713), consisted in adopting in full all the decisions taken at that conference as the basis for the determination of the borders between the belligerent countries, and the establishment of a league of European nations (International Federation) whose mission was to prevent conflicts. Apart from this utopia, and more important at the time, there were the Peace Treaties of Westphalia, signed in 1648. They intervened at the end of a Thirty Years' War, conducted under religious banners, resulting in an accumulation of hatred and in the destruction of 40% of the population. The negotiations lasted four years (1644-1648). Ultimately, they enshrined the principle of equality in negotiations between all parties in conflict, whether Catholic or Protestant, republican or monarchical. The Treaty of Westphalia laid down four fundamental principles: 1. The absolute sovereignty of the nation-state, and the fundamental right to political self-determination. 2. Legal equality between nation-states. The smallest state is, therefore, equal to the largest, regardless of its weakness or its strength, its wealth or poverty. 3. Compliance with treaties, and the emergence of binding international law. 4. Non-interference in the internal affairs of other states. Certainly these general principles do not determine an absolute sovereignty, but there never was such a thing. However they did delegitimize any action likely to abolish the sovereignty of a state. Political philosophers have all supported these projects. Rousseau strongly called for the constitution of a single state contract involving all