We remember Thucydides as a historian thanks to his documentation of the Peloponnesian War, but we often forget that he was also a philosopher. And like all great philosophers, he has many things to teach us, even if his teaching is inappropriately applied. Thousands of years after the war was fought between Sparta and Athens, observers argued that it showed that an authoritarian government would defeat a democracy. This was widely said in the early stages of World War II and repeated throughout the Cold War. In truth, what Thucydides said about democracies and oppressive regimes was far more sophisticated and complex than a simplistic slogan invoked by defeatists.