Because we’re all so obsessed with what it was that made the Nazis tick, we tend to overlook the bigger mystery of how hundreds of millions of people, for a period considerably longer than the lifespan of Hitler’s Germany, remained under the spell of communism.

This is a question that Czeslaw Milosz set out to answer in his 1953 classic The Captive Mind. Milosz was a Polish poet, prominent in the underground during the Nazi occupation, who served as a cultural attaché with Poland’s post-war communist regime before quitting in disgust and fleeing to the US, where he taught at Berkeley and achieved eminence as a Nobel-prize-winning dissident exile.

What Milosz particularly wanted to know was how so many of his literary and intellectual contemporaries embraced dialectical materialism — the only permitted way of thinking in the ‘imperium of the East’ — when, being intelligent and cultured and sensitive, they ought to have seen it was a nonsense that bore no relation to observed reality.

He came up with a number of explanations, one of which captures perfectly that preening sense of entitlement you found then and still find now among luvvie types. Under communism, Milosz explains, artists prepared to endorse the regime are given enormous privileges and power, while simultaneously being freed from having to engage in the kind of struggle or suffer the insecurity that traditionally besets their profession. This appeals to their amour-propre, and gratifies their instinct that they are far more important than the ‘businessmen, aristocrats and tradespeople’ who have previously looked down on them as effete outsiders.

Milosz was writing in the 1950s about life behind an Iron Curtain now so remote and ill-understood as almost to have been airbrushed from history. (Why else would so many kids today find the politics of Jeremy Corbyn, Bernie Sanders and the Occupy movement so fresh and exciting?) But what may strike you as you read his book is how relevant his insights are to the supposedly liberated culture we now inhabit.

For decades, we have told ourselves we are free — as indeed, compared with places like the old Soviet Union, North Korea and China, we are. But what most of us have failed to see, barring the odd brave exception such as Roger Scruton, is the degree to which we have ourselves become prisoners of politically correct groupthink. We don’t have gulags and we don’t put dissidents in loony bins, but the required conformity of thought is little less crushing, stultifying and intellectually corrupt.

Perhaps the most obvious example of this is the BBC, which of course believes passionately in freedom of speech. But you try submitting a thriller where the bad guys are Muslims or there isn’t a female lead at least as feisty and empowered as the males; or a documentary arguing that the climate-change scare is a hoax or that immigration needs to be controlled; or a news report that sees the positive in Donald Trump and Brexit or the bad in the EU, Palestinians or the White Helmets defending free Syria — and see just how far your freedom of expression gets you.

Some countries have it even worse than us: Canada, for example, where one university banned yoga classes because it considered them ‘cultural appropriation’. And where, more recently, they have passed legislation which has prevented one of the world’s leading child psychiatrists, Dr Kenneth Zucker, treating children with gender dysphoria in a way that steers them away from hormones and life-changing surgery.

There was a fascinating programme about this the other day (on the BBC: God knows how it slipped through the net) called Transgender Kids: Who Knows Best? You’d think, wouldn’t you, that for a child confused about gender identity, a sex change ought to be the last resort. (‘A four-year old might say he’s a dog — do you go out and buy dog food?’ asked Zucker, not unreasonably.) But such is the power now of the trans lobby that, thanks to a particularly vocal MP, the talking-cure route has been stigmatised, and the traumatising, unnatural and permanently disfiguring one codified into law.

I offer that as particularly extreme example of the madness into which PC — the armed wing of cultural Marxism — is leading us. Yes, I appreciate that there has been resistance to the transgender lobby, some of it from commentators on the liberal left, such as Germaine Greer. But this has more to do, I fear, with the fact that it’s new territory on which acceptable groupthink has yet to be established, rather than that the lefties are suddenly becoming ‘woke’ to the totalitarian consequences of their identity politics.

The sad fact is that most people, even intelligent ones, find it easier to submit to self-censorship than to take the hard path of challenging the prevailing orthodoxies. Right-wingers are often just as guilty. When was the last time you heard a Conservative MP express reservations about the NHS? How many free-market economics commentators question the system whereby spendthrift governments can create money they don’t have — and isn’t theirs — through cheats like quantitative easing? How many right-wing pundits, come to that, have resisted the urge to virtue-signal by banging on about how much they deplore Donald Trump’s vulgar populism?

‘Any civilisation, if one looks at it with an assumption of naive simplicity (as Swift looked at the England of his day), will present a number of bizarre features which men accept as perfectly natural because they are familiar,’ writes Milosz. If, as I believe, Brexit and the advent of Donald Trump are modern western culture’s equivalent of communism’s Berlin Wall moment, then a lot of us — artists and intellectuals especially — are about to suffer a very rude awakening.