It is not easy today to convey the great optimism that the destruction of the wall brought, nor is it possible to pretend that there was not a degree of premature triumphalism. To use a language from another time, the red barbarians had reached the gates of old Europe and they had been repelled.

George HW Bush was in the White House and Margaret Thatcher was in the twilight of her premiership. Each used the fall of communism to remind the world the values they held dear — democracy, open markets, individual choices, minimal government, and energetic capitalism — had prevailed.

They could not have imagined how that victory would, within three decades, be the catalyst for a surge to the right, a renewed and unsustainable concentration of wealth and, to a very large degree, climate change.

Neither could they have imagined that the old politbureau communism would be replaced by an authoritarian kleptocracy, no more than they could have imagined US president Donald Trump or British prime minister Boris Johnson. Who could have?

The collapse of the Berlin Wall is one of the few seminal events in the modern world that can be compared realistically with an alternative event, one that offers a stark lesson in what could have happened had the Soviet Union used its undoubted power to try to maintain its position.

Germany, Europe, Russia, and the rest of the world too, owe a debt of immeasurable gratitude to the eighth and last leader of the Soviet Union Mikhail Gorbachev, who refused to use military force, as his predecessors had, to crush opposition.

Had he been as aggressive as Deng Xiaoping was when, in that same year, he ordered China’s army to put down Tiananmen Square protests, it is impossible to imagine the outcome. Could the West have looked on as it did when the Soviets crushed earlier revolts behind the Iron Curtain?

No-one can answer that question but we must be grateful that it did not have to be answered. Especially as the intervening decades offered other examples — the Arab Spring — of how things can go wrong when when hope and authoritarinism collide.

The fall of the Berlin Wall led to the reunification of Germany, a process which chanceolor Angela Merkel describes as incomplete. It is, however, one of Europe’s most powerful examples of the potential of unity and political stability, so it will be celebrated with justified gusto in the coming days.

Next month marks the 20th anniversary of the effective implementation of the Belfast Agreement and the end of the border on this island. Let us hope that when its 30th anniversary comes, the idea of an Irish border will seem as bizarre as is the idea of rebuilding the Berlin Wall.