I watched Selma a few weeks ago. It's a multi-layered film about a multi-layered issue. But although those issues have remained relevant over the past five decades, I hadn't expected there to be such a clear and obvious relevance right now.

One of the themes of the film - because it's one of the themes of the era - is of the conflict between bigoted Southern politicians and federal leaders - specifically, LBJ - attempting to deal with that bigotry.

There are many reasons to despair over what happened at Charlottesville this past weekend, but here’s one: the dynamic outlined in Selma (and then over the decades beyond) has been reversed. The story this time has been of a Southern state’s governor – Terry McAuliffe of Virginia – speaking eloquently and powerfully against racists and fascists, while the US President cannot bring himself to speak (or, one has to say, tweet) a single word of specific criticism of those racists and fascists.

You hardly need me to point out how appalling this is.

Among the many shocking scenes in Charlottesville, neo-Nazis chanted “Jews will not replace us”. This is not a game. It is not pretend. It is real. Real in the sense that there was serious violence – one counter-demonstrator was killed – and real in the sense that these people have an agenda and are deliberately and carefully going about fulfilling that agenda.

Let’s put that in perspective. Neo-Nazis, KKK, white supremacists; they’ve been around for many decades in the US and although they are capable at varying times of causing immense suffering and anxiety, in the great scheme of things they have got nowhere.

But.

There is one big difference now. For the first time, there is a US President whom they not only claim as one of their own but who has quite intentionally used these very dark forces for his own political ends.

Despite the caricature, Donald Trump is not an idiot. He might be a braggart and entirely unfit for high office but he is not a total fool. He knows what he doing when he speaks. And when he speaks for a long time on the events in Virginia and draws an equivalence between white supremacists and those who oppose them, he knows exactly what he doing. Which is also what he is doing when he refuses to issue a specific condemnation of the chants and the violence – indeed of the very presence – of neo-Nazis.

But nothing about this is in any way surprising. This is exactly how Trump campaigned, and it is exactly how he has governed. His campaign utilised the very same tactics. Just as now he has not praised the forces of darkness, so he didn’t praise them during the campaign and hasn’t done since being elected. But – vitally – nor did he utter a word of criticism of them during his campaign, and nor has he now. The opposite, in fact: his campaign and its rhetoric was designed to unleash them.

Think about this: can you imagine a single post-WW2 US president not denouncing any neo-Nazi who dared to claim him as an ally?

But the White House is now occupied by a president who is – to put the least worrying spin on it - comfortable with white supremacists and their behaviour.

Yet that really is the least of it. Trump deliberately unleashed the forces of darkness in his campaign and has ridden them ever since. History shows us that those forces can take on a hideous and unpredictable momentum. The real issue arising out of Charlottesville is what comes next – and how US democracy responds when the leader of that democracy seeks to capitalise on that momentum.