There is much to learn from Paul Johnson's history of the 20th century, not least the appalling truth about the "Republican" camp during the Spanish Civil War; some unpalatable facts about FDR and his "vanity … compounded by an astonishing naivety"; and, most importantly, the many ways in which the autocrats of the left (Lenin, Stalin, Mao, etc…) and of the right (Hitler, Mussolini, Pétain, etc…) inspired, complemented, and even conspired with, one another. Much of what we have learned turns out to be myths. What explains the rise of rightist fascism, and how does it differ from leftist communism?...