She had the eyes of Caligula and the lips of Marilyn Monroe. So said Francois Mitterrand, the last serious socialist to lead a major European nation, speaking of Margaret Thatcher, who helped bury socialism as a doctrine of governance. She had the smooth, cold surface of a porcelain figurine, but her decisiveness made her the most formidable woman in 20th-century politics, and England’s most formidable woman since its greatest sovereign, Elizabeth I. The Argentine junta learned of her decisiveness when it seized the Falklands. The British, too, learned. A Tory MP said, “She cannot see an institution without hitting it with her handbag.” She aimed to be the moral equivalent of military trauma, shaking her nation into vigor through rigor. As stable societies mature, they resemble long-simmering stews — viscous and lumpy with organizations resistant to change and hence inimical to dynamism. Her program was sound money, laissez faire, social fluidity and upward mobility through self-reliance and other “vigorous virtues.” She is the only prime minister whose name came to denote a doctrine — Thatcherism. (“Churchillian” denotes not a political philosophy but a leadership style.) When she left office in 1990, the trade unions had been tamed by democratizing them, the political argument was about how to achieve economic growth rather than redistribute wealth, and individualism and nationalism were revitalized.