I did the first study because I had been exposed to something that I took to be important and interesting - this thought reform process - in the military.

Again, I was influenced by my father, who was very much an atheist and took pride in combating the traditional or orthodox forms of Judaism, which his parents and which my mother's parents were very steeped in.

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.

One reason that I embarked on a study of Nazi doctors was that in this personal journey, I had the feeling increasingly that I did want to do a Holocaust study and that increasingly I wanted it to be of perpetrators, which I thought was more needed.

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.

The scientists who made the atomic bomb are, in my sense, people with a tragic destiny. You know, there was the US race with Nazi Germany and good evidence that the Germans were more advanced in nuclear physics, and we had to get the bomb first. But then there was the use of that dreadful weapon, or instrument of genocide, and many of the more sensitive scientists turned quickly into anti - nuclear people - and very effective ones.

As a kid I was fascinated with sports, and I loved sports more than anything else. The first books I read were about sports, like books about Baseball Joe, as one baseball hero was called.