It is a cliché that if we do not study the past we are condemned to repeat it. Almost equally certain, however, is that if there are lessons to be learned from an historical episode, the political class will draw all the wrong ones — and often deliberately so. Far from viewing the past as a potential source of wisdom and insight, political regimes have a habit of employing history as an ideological weapon, to be distorted and manipulated in the service of present-day ambitions. That's what Winston Churchill meant when he described the history of the Soviet Union as "unpredictable." For this...