It's Holocaust Memorial Day this Friday. I'll never forget a Holocaust Memorial event a few years ago where I heard two Auschwitz survivors speak. Their talks were fascinating, but the bit that's stuck with me ever since is an exchange they had after their talks were finished. One of them was convinced the Holocaust could happen again: the other was adamant that it couldn't.
I remember wrestling with this question for a long time afterwards. Could it really happen again? Surely we've learnt the lessons of history by now - we can at least take that for granted?
But of course, the past year has shown us that nothing can be taken for granted. Yes, people had different and complex reasons for voting for Brexit and Trump. Many were sincere and honest reasons, and those of us who opposed them may yet be proven wrong, at least on some of our assumptions and beliefs.
But a good many people had reasons for supporting Brexit or Trump that we should never condone. The atmosphere of xenophobia was strong both in the run-up to and immediate aftermath of the June EU referendum - as were the incidents of abuse and violence. Theresa May has condemned this, but I've waited in vain for such condemnations from Nigel Farage, Boris Johnson and Michael Gove. I suppose Johnson was too busy forging his path to Number 10, and Gove and Farage preoccupied with sucking up to Trump, to worry about a few hundred abused and attacked EU nationals.
And it's the growth of this hatred in the US and abroad, facilitated by Trump in his vehemently polemical campaign, that worries me. Look at some of the support that Trump has gained - endorsements from the KKK, cheers from Neo-Nazis, and crowds chanting "We hate Muslims, we hate blacks, we want our great country back" after his election victory was announced.
You might say those are simply extreme fringe groups - what sway can they possibly have? Yet Steve Bannon, when he wrote Trump's inauguration speech and made the phrase "America first" a centrepiece, knew full well that this was not simply an innocuous statement about the new government's priorities. It's a slogan that was popularised by American Nazi sympathisers in the 1930s.
To me that's deeply disturbing. But to be clear - I'm not saying Trump is Hitler or a neo-Nazi. I'm saying he's deliberately influenced the public's views and used his powerful position to stoke up hatred and division.
And that must be a lesson we learn from the past. The rise of Hitler (which after all was achieved through democratic elections) shows us how easy it is for people in power to influence the public's opinions, turn people against one another and stoke up violence, fear and hatred.
I still don't know if the Holocaust could happen again. I really hope it couldn't. But what I do know is that we must guard against our society becoming divided by leaders who stoke up hatred.
How? I don't have an easy answer. But we can start by calling out prejudice in the powerful and in the less powerful. The global women's march was a great start for sending a powerful message. (Those who objected to the march on grounds that Trump was democratically elected completely missed the point. It's not about overthrowing Trump; it's about people using their voices in a free society to influence those in power, and remind them they're accountable to the public).
And perhaps above all, we can commit ourselves to always remembering, and striving to understand, the darkest hour in modern history, and vowing that we will never again allow the attitudes of prejudice and hatred that enabled the Holocaust, to grip our society.