‘They all laughed at Christopher Columbus,’ sang my husband flatly, ‘when he said the world was round.’ I wasn’t going to tell him yet again that George and Ira Gershwin were wrong and everyone knew the world was round when Columbus set off. But there is a connection between Columbus’s name and the leap in the dark that he took in his voyage — and which David Cameron says ‘outers’ want to take today.

I’ll stick to language, since this is not a political column. That very English word leap has no affinities in languages outside the Germanic family, unless, some scholars say, it is related in origin to the rather different-looking Greek word kolumbos, meaning ‘diver’. Aristophanes used that word in The Birds, and ordinarily it meant rock-dove, like the London pigeon. It is supposed to swim through the air, like a pearl diver in water. Christopher Columbus’s surname is a latinised form. To Italians he is Colombo and to Spaniards Colón. We anglicise his Christian name, but we could go further and make his surname Dove or Pigeon — or Diver or Leaper.

As for leap in the dark, I don’t know that anyone has found the phrase earlier that in Vanburgh’s play The Provoked Wife (1697). The line is: ‘Now I am in for Hobbes’s voyage; a great leap in the dark.’ E. Cobham Brewer, in his Dictionary of Phrase and Fable, asserts that the dying Hobbes said: ‘Now I am about to make my last voyage — a great leap in the dark.’ No source is given. I expect the great Hobbes scholar Sir Noel Malcolm knows, if anyone. Anyway, it became proverbial enough for Defoe’s Moll Flanders to talk disapprovingly of wanting to make ‘matrimony, like death, be a leap in the dark’.

Nearly 150 years ago, the Second Reform Bill of 1867, which extended the franchise greatly, had been called a ‘leap in the dark’. Tenniel drew a dull but famous cartoon. Lord Derby was not cowed: ‘No doubt we are making a great experiment, and taking a leap in the dark, but I have the greatest confidence in the sound sense of my fellow countrymen.’ It seems not to be a confidence that Mr Cameron shares.