It didn't rank quite as highly as the atom bomb, but, in a poll of 2,000 adults, the mobile phone was up there on the list of man's most undesirable inventions.

Note that this was a survey of adults. There would have been a different result if young people had been surveyed: most of them might not have even realised it was an invention, more of a birth right. But for those of us of a certain age, the mobile is, at best, a mixed blessing, bringing with it the threat of an irradiated brain alongside the benefit (if that's what it is) of being in constant communication.

It is now hard to imagine a world without mobiles. How did we meet in a crowd? What did we do on a bus? Did we have to remember everyone's number? The world seemed to function perfectly well, but, on a cost/benefit analysis, the advent of the mobile phone has probably been a boon to humankind.

However, as our Prime Minister is discovering, there is one aspect of a mobile's function that may have been better left uninvented. Texting is convenient and practical – it obviates the need actually to speak to anyone and avoids ruinous call costs – but, as a source of trouble in the modern world, it has few rivals.

David Cameron is under pressure at the moment to reveal the text messages – said to number 150 – he sent to Rebekah Brooks when she was, as well as his neighbour and the wife of an old friend, running Britain's most powerful media organisation. Now, the whole point about texts is that they are a very personal means of communication: the email is primarily a business tool, Twitter is for the dissemination of information, and a text is a closed exchange between two people who know each other well enough to share mobile phone numbers.

A person's text messages should remain their own propert

Thus the language used in a text is more informal, jokey, friendly, and, yes, flirty. A text is only meant to be read in the present, and is certainly not supposed to be preserved as a historical document. How many couples do you know whose relationship has been put under strain by one partner reading the other's text messages? Of course, they may present prima facie evidence of infidelity, but a text read in the cold light of day, without the intended nuance and missing the context, can appear much more incriminating than it actually is.

We know all about Mr Cameron signing off a text to Mrs Brooks with an un-ministerial LOL, believing it stood for lots of love, and now two more of his infelicitous messages have made it into the public domain, increasing the din for the others to be revealed. We already know Mr Cameron and Mrs Brooks had a questionable closeness, so we should curb our voyeuristic instincts.

A person's text messages – whether they be Prime Minister or not – should remain their own property. Text messages, hastily composed and inspired by the moment, are like our thoughts. And we know what those are like: embarrassing, rambling, mundane, inappropriate and, yes, private.