Scholars used to speak of the "Cleopatra's nose" theory of history; the idea that if the Egyptian queen's nose had been shorter Caesar would have been less bewitched and the course of history different.
Now a historical documentary is offering us the "Henry VIII's hose" theory of the past. If the bluff sovereign had not fallen off his horse in a 1536 joust, it claims, his leg problems would have been less severe and he would not have turned into such a grumpy old tyrant.
But we should beware of assuming that Henry would have been any less disruptive if he had been fit and healthy. By 1536 he had already broken with Rome, divorced Katherine of Aragon and executed his old friend Thomas More.
Just think what Henry might have perpetrated over the next 11 years of his reign if he had been more mentally and physically able. That fall was certainly a curse for old Henry, but might it have been a blessing for the rest of us?