It may or not have been Plato who said it first, but I like it anyway: 'As empty vessels make the loudest sound, so they that have the least wit are the greatest babblers.'
If it isn't already, I suggest it should be inscribed in gold lettering over the entrance to the White House. After all, it is the home - at least for now - of the US's undisputed Babbler-in-Chief.
I have, belatedly, learnt to stop worrying so much about his babblings, because I have come to the conclusion that they have little or no significance beyond signalling the emptiness of the vessel from which they emanate. (I am well aware of the risks of tempting fate, but I still think the point is worth making.)
Pride of place in the Babblers' Hall of Fame came just a couple of days ago when, as the New York Times headline put it: 'Trump Makes Puzzling Claim That Rising Stock Market Erases Debt.' The story's first line said it all: 'President Trump suggested on Wednesday evening that a soaring stock market might be "in a sense" reducing the national debt, a statement that is not true, in any sense.'
As for the much-heralded wall along the border with Mexico? Babble. The repeal of Obamacare? More babble. (His latest attempt, by cutting off government subsidies to health insurers, faces immediate challenge in the courts.) The 'total destruction' of North Korea? Babble, babble. (Thank goodness.)
Over the past few days, we've had threats to revoke the broadcasting licences of TV networks such as NBC (the babbler doesn't have the power to do that), and the staggeringly inane remark that 'It's frankly disgusting the way the press is able to write whatever they want to write.' (I'd love to be the White House aide who draws his attention to the first amendment to the US constitution: 'Congress shall make no law ... abridging the freedom of speech or of the press ...)
So I'm not exactly surprised that, according to a hair-raising account in Vanity Fair, the president 'seems to be increasingly unfocused and consumed by dark moods', largely because he hasn't been able to do any of the things he wants to do.
Those of us who are terrified by the prospect of him actually achieving any of his policy objectives have some reason to be thankful. But that is not the same as being complacent - one thing he can do is launch a nuclear attack, and there have been several reports suggesting that he sometimes seems to be itching to do just that.
According to Vanity Fair, 'One former official even speculated that [White House chief of staff John] Kelly and Secretary of Defense James Mattis have discussed what they would do in the event Trump ordered a nuclear first strike.' The question being, of course, would they be able to stop him?
None of this is meant to suggest that the Trump presidency has had no impact anywhere. According to the New York Times, the Environmental Protection Agency, which under its Trump-appointed director has adopted a policy of doing as little as possible to protect the environment, has 'moved to undo, delay or otherwise block more than 30 environmental rules, a regulatory rollback larger in scope than any other over so short a time in the agency's 47-year history.'
And even without a border wall, the number of illegal immigrants caught trying to get into the US from Mexico has dropped by 20% compared to last year. Mind you, this is in large part the continuation of a well-established trend: when I was last in Mexico four years ago, there were already more migrants crossing south from the US into Mexico, because of economic stagnation north of the border, than there were crossing in the opposite direction.
The truth is that when the babbling emanates from the White House, it can sometimes have an impact even if it is not translated into executive action. It makes a noise, and people adjust their behaviour accordingly. The number of refugees being admitted from Muslim-majority countries has fallen, for example, even though the president's 'Muslim travel ban' has remained largely frozen by court rulings.
It also has an obvious impact on the way the rest of the world regards the US. The president is its symbol, and if the president is an incoherent babbler with only the most tenuous grasp of reality, well, that's not great news for the nation's global reputation or its ability to protect its national interests.
Which brings us to the Iran nuclear deal, which at the time of writing, President Trump is reported to be preparing to 'decertify'. But again, it is perfectly possible that whatever he says (remember 'the worst deal ever negotiated'?), it may amount to little more than yet more babbling.
All the other signatories to the agreement - Russia, China, France, Germany, the UK, and the European Union - are determined to make it stick. How Iran might react to more Trump babble, however, remains an open question. As does the reaction from Kim Jong-un in Pyongyang.
The US secretary of state Rex Tillerson is reported to have called Trump 'a (expletive deleted) moron' after a meeting in which the president apparently suggested that the US should increase its nuclear arsenal ten-fold. So in future, when Tillerson seeks to reassure nervous allies abroad, I suggest he simply tells them that the Babbler-in-Chief is babbling again, and they should take no notice.
It might make them - and us - feel just a little bit safer. Or not.