'The facts speak only when the historian calls on them," EH Carr argued in his landmark essay, The Historian and His Facts, almost 50 years ago. "It is he who decides to which facts to give the floor, and in what order or context … It is the historian who has decided for his own reasons that Caesar's crossing of that petty stream, the Rubicon, is a fact of history, whereas the crossing of the Rubicon by millions of other people before or since interests nobody at all."