Plato : justice and the rule of philosophers -- Aristotle : practical wisdom and the best state -- Augustine : the foundations of realism -- Aquinas : the Catholic vision and the just war -- Machiavelli : realpolitik -- Hobbes : war and the laws of nature -- Rousseau : the impossibility of international harmony -- Kant : the idea of perpetual peace -- Hegel : the march of world history -- Clausewitz : the strategic dimension -- Marx : the collapse of international capitalism.