‘Quotation (n.) — The act of repeating erroneously the words of another.’ Ambrose Bierce said that, or at least wrote it in theDevil’s Dictionary. That was in 1906, and those are words for the ages. In his Rhetoric, centuries before the birth of Christ, Aristotle identified one of the most common and effective ways of making an argument seem stronger. In his section on ‘proofs’ he talked about what he called ‘ancient witnesses’. By this he meant not only the testimony of witnesses such as you might call in court — but the witness borne by proverbs and quotations.

Any speaker or writer can get an extra fillip of authority by quoting a revered forbear. Don’t just take my word for it, we say: Shakespeare or Montaigne put it best. A snappy quotation — quite against the obvious rules of logic — has a way of presenting an argument as settled. As Auden wrote, introducing an anthology of aphorisms: ‘An aphorism… must convince every reader that it is either universally true or true of every member of the class to which it refers, irrespective of the reader’s convictions.’

That instinct is still strong with us. From Instagram #inspo — an image macro, say, with the words ‘an eye for an eye will make the whole world blind’ superimposed on a thoughtful photo of the underpants model David Gandy — to political speeches in the high style, we love a quotation. We wrap ourselves in them, as Rudyard Kipling nearly said, as a beggar would enfold himself in the purple of emperors. And we love a quotable figure: orphaned witticisms and loose-end aphorisms flock to figures such as Winston Churchill, Oscar Wilde, Mark Twain and Dorothy Parker. The fabled wit of the authority and the evident wit of the quote reinforce each other pleasingly.

The internet has changed all this in a dismaying number of ways, though. In the first place, it makes it much harder to show off. Fifty years ago, a columnist — fat dictionary of quotations to hand — could offer a thrilling air of offhand erudition by wondering in print: ‘Wasn’t it Rousseau who said…?’ Nowadays, his or her Google-using readers are likely to reply: ‘No, it wasn’t.’ Or: ‘I don’t know. Why don’t you Google it, lazybones?’

And the further problem is that when you do Google it, you’ll find that, no, indeed it wasn’t. Or that it might have been but it might equally well have been any number of other people. Or that he said something similar but we’re actually quoting an early 20th-century précis, and misquoting it at that.

Websites such as Quote Investigator are doing the honourable, scholarly, infuriating Snopes-like work of debunking almost every quote you think you know. ‘When the facts change, I change my mind. What do you do, sir?’ John Maynard Keynes, right? Wrong. He never said anything like it, not that it stopped Prospect from using the quote as a strapline for many years. ‘A billion here, a billion there — pretty soon it begins to add up to real money.’ US Senator Everett Dirksen? Uh-uh. ‘When people stop believing in God, they don’t believe in nothing — they believe in anything.’ Chesterton? Alas not.

Did Socrates, I found myself checking recently in the way that you check something you’re pretty sure of, say that losing his sex-drive in old age was like ceasing to be chained to a lunatic? Er, nope. It was Sophocles, as paraphrased by Plato, and what he said, or is said to have said, is that it was like having ‘escaped from a frantic and savage master’. George Melly said it was ‘like being unchained from a lunatic’, the comedian Paul Whitehouse attributed to Kingsley Amis the notion that the male libido was like ‘being chained to an idiot’, and the closest version to my own was, I’m snobbish enough to have been embarrassed to discover, from Russell Brand in My Booky Wook: ‘Socrates says the male libido is like being chained to a madman.’

Anything you think you know, it turns out, you don’t. And Russell Brand also doesn’t know it. In fact, there’s a quotation for that. Mark Twain, as we all know, warned: ‘It ain’t what you don’t know that gets you into trouble. It’s the things you know for sure that just ain’t so.’ Except, of course, nothing like that appears anywhere in his work. (If you want to know the detail, Quote Investigator will send you down a 20-minute rabbit-hole.)

All this does us, though, something of a service. Misquotation and misattribution were abundantly analogue vices — Twain was being misquoted on that line before the end of the 19th century, and don’t let’s get started on ‘reports of my death’ — but only in the era of vast searchable digital corpora did the authoritative debunk really get its boots on. So we know more, now, about what people did and didn’t say; and we know more, however dismayingly, not only about the dubious sources of this apocryphal wisdom but about how it reaches us.

Like jokes and — towards the end of the process — proverbs, quotations circulate through the culture and get attritionally knocked into smoothness like pebbles in surf. Look at ‘blood, sweat and tears’: the final form of the phrase takes Churchill’s ‘blood, toil, tears and sweat’ and turns it into a tricolon, along the way giving it metaphorical coherence (‘toil’, quietly elided, is the only one that isn’t a bodily fluid).

And in the end, the misattribution is neither here nor there. It’s not the origin of a quote so much as the zing and polish of its final form that matters. If it has had the pithiness and staying power to become the sort of thing that’s widely misattributed, you could say it has gone beyond the wit of one man or woman and entered the store of common wisdom of the tribe.

‘I wish I’d said that!’ Wilde said to Whistler. ‘You will, Oscar, you will,’ retorted Whistler. Or did he?