In his successful 2016 election campaign, Donald Trump used a number of slogans which he and his supporters repeated ad nauseam.
They memorably included "lock her up" and "build the wall" - but the one that seemed to resonate most effectively with American voters, and still does, was "make America great again".
There is nothing wrong with the sentiment, but it has proved to be something of a chimera, since Trump has fallen into the habit of linking it to another slogan which he also uses most of the time.
As he meets world leaders at the United Nations this week, we were assured in pre-briefings that he will be focused on "putting America first" and that is what - to the amusement of his audience - he delivered.
His declared preference for patriotism over globalism is a further sign of his lamentable inability to understand how the world really works; he does not seem to recognise the disjunction between the two slogans - that "putting America first" is not necessarily the best way to "make America great again" and might actually work against that second objective.
If we look back now at how the global scene played out in the post-war era, it is surely clear that one of the reasons for America's emergence as the world's premier power was the fact that they were willing to become the leading force in the establishment of major institutions that helped to create an international world order.
It was not, in other words, their pre-eminence as a military or economic power, but their readiness to use that power, in conjunction with others, in multilateral
efforts to build peace and prosperity across the globe - not least through the Marshall Plan, so vital to Europe's regeneration - that made America a super-power and guaranteed them a sort of moral leadership.
Trump, however, seems unaware that US support for the United Nations and for NATO, for the World Trade Organisation and for many other multilateral attempts - like the International Criminal Court - to secure coordinated action on many of the problems facing the world, was what really "made America great".
Instead of embracing and reinforcing this valuable role, Trump has insisted on slamming on the brakes and going smartly into reverse.
So, we have seen him tearing up the WTO rulebook, lecturing NATO on its failings and threatening to cut the US contribution to its budget, behaving similarly at the United Nations (where he has already cut or ended American funding for refugee aid - particularly in Palestine), abandoning the Paris Accord on Climate Change, unilaterally withdrawing from the nuclear agreement with Iran and re-imposing sanctions instead, without consulting other countries (formerly regarded as America's allies) who were parties to the same agreement.
Trump of course has a point in that organisations like the UN and NATO have depended heavily on American financial support, but saving a few dollars - which, when spent in the past, could be regarded as the price to be paid for America's dominant role and influence - is not necessarily the best (or any) way to "make America great again".
Trump's disregard - perhaps even contempt - for the leadership role America has embraced so effectively in the past is completely at odds with - indeed, a specific denial of - the very elements which made America great.
Across the board, we now see an American President who celebrates the sacrifice of American leadership of what used to be called "the western world" and gives priority to "putting America first" through saving a few dollars and impressing his "base" with his "toughness" as the mid-term elections approach.
There can be few examples on such a broad scale of such a narrow mind failing to encompass and understand such broad and important issues - or of a major country deliberately throwing away its influence in the world.
America may be many things under Trump's leadership but "great again" is unlikely to be one of them.
His other campaign slogans don't look as though they will be much help either.
Being "locked up" seems a more likely fate for some of Trump's closest advisers than for Hillary Clinton, and "building the wall" is as far away and fanciful as ever.