I think one thing writers can do is point out that you don't have to say openly racist things, like [Donald] Trump, to be a racist or a xenophobe.

All of us living in today's world are facing an enormous crisis - arguably the greatest that humanity has ever faced - in the form of man-made global warming; one can't be neutral at such a moment. It's like claiming to be neutral if you're living in Germany in 1933.

And yet the world we live in-its divisions and conflicts, its widening gap between rich and poor, its seemingly inexplicable outbursts of violence-is shaped far less by what we celebrate and mythologize than by the painful events we try to forget. Leopold's Congo is but one of those silences of history.

Newt Gingrich seldom misses a chance to note that he is a historian.

You know, by 1936, Hitler was already talking very loudly about his desire to expand to the east. Mussolini, in 1935, went and then in the next year, conquered Ethiopia, acquiring himself a colony. So people at the time really saw fascism not just as an evil but as an aggressive evil that seemed to be spreading.

Growing inequality is a huge problem, and of course is intimately connected to xenophobia and racism.

Speaking of Germany in 1933, I don't think you can remove yourself from politics when, in so many countries - the United States, Poland, Hungary, and many others - you've got politicians in power or vying for power who are taking tactics and elements of their appeal from the playbook of fascism.