While Donald Trump doesn't have any systematic ideology, he does have a narrative, and in that narrative, America was once a great country, it's been weakened by poor leadership, and only he can make it great again by taking over. And that's an image of himself as a strongman, a dictator. It isn't the clear ideology of being a fascist or some other clear-cut ideological figure. Rather, it's a narrative of himself as being unique and all-powerful. He believes it, though I'm sure he's got doubts about it.

But I spent just two calendar years at Cornell University, though it was covering more than three years of work, and then went to medical school and did become interested in psychiatry, and even helped form a kind of psychiatry club in medical school.

There's more and more recognition that a carbon economy is dangerous to us economically. And there is increasing recognition that renewable fuels have economic value as well as obvious value for our health and our well-being and our survival. In fact, as you know, the economic revolution in renewable fuels has been impressive. It really had not been anticipated.

I don't have the feeling that as a very young person I read books that absolutely made their mark on my mind.

Donald Trump gives the impression that he would like to govern by decree. He has that impulse in him and he wants to be a savior, so he says, in his famous phrase, "Only I can fix it!" That's a strange and weird statement for anybody to make, but it's central to Trump's sense of self and self-presentation. And I think that has a lot to do with his identification with dictators. No matter how many they kill and no matter what else they do, they have this capacity to rule by decree without any interference by legislators or courts.

People with what we call mental illness can indeed serve well, and people who have no discernible mental illness - and that may be true of Trump - may not be able to serve, may be quite unfit. So it isn't always the question of a psychiatric diagnosis. It's really a question of what psychological and other traits render one unfit or dangerous.

I'm a Brooklyn boy. I was born in Brooklyn, New York, and raised there, and spent most of my childhood there.