In this essay Wight surveyed concepts and events from Graeco-Roman antiquity to modern times dealing with the impact on international politics of chance, destiny, fate, fortune, freedom, irony, luck, necessity, providence, tragedy, and will. The ancient sources cited include Horace, Plutarch, Polybius, Thucydides, and Virgil. The political philosophers considered range from Machiavelli to Burke and Marx. Among the reflective political leaders cited are Bismarck, Cavour, Cromwell, Gladstone, Lincoln, Lloyd George, and Napoleon. The twentieth-century decision-makers quoted extend from Adenauer, Churchill, de Gaulle, Dulles, and Roosevelt to Hitler and Mussolini. Wight distinguished between ‘opportunism of ends’ and ‘opportunism of means’. Opportunism that creates propitious circumstances may overlap with opportunism that waits for—and prepares for—a favourable time and seizes the chance at hand. Unintended, unexpected, and ironical consequences abound in international politics.