The essay sets out practical and normative conditions for securing lasting peace between states, first listing prohibitions—no secret reservations to peace treaties, no annexation of states by inheritance or purchase, abolition of standing armies, prohibition of public debt for external affairs—and then proposing definitive principles: republican civil constitutions, a federation of free states under international law, and a cosmopolitan right limited to universal hospitality. It combines juridical argumentation with moral and political reflection, assesses institutional reforms, and adds appendices that examine tensions between morality and statecraft and the alignment of politics with principles of public right.