Tony Schwartz wrote Trump’s best-selling memoir, The Art of the Deal. In 1987 it spent 48 weeks on the New York Times Best Seller list. More than a million copies have been sold. Schwartz has written other bestsellers—and his essay, “I wrote ‘The Art of the Deal’ with Donald Trump” is featured in the new book edited by Bandy Lee, The Dangerous Case of Donald Trump. This interview has been edited and condensed.

Listen to Tony Schwartz on the Start Making Sense podcast.

Jon Wiener: How much time did you spend with Donald Trump when you were working on Art of the Deal?

Tony Schwartz: I spent 18 months from start to finish, and during the majority of that time, I was essentially sitting in his office on an extension phone listening to him talk to a vast range of people over the course of a day. When he wasn’t in the office, I was usually traveling with him. So I spent hundreds and hundreds of hours with Trump.

JW: How different was Trump in the mid-’80s from the man we see now?

TS: Until several months ago, I would have said not all that different. He was then and is now always 100 percent self-absorbed, incapable of interest in other human beings, and completely self-referential. He viewed every event through the lens of its impact on him. Even 30 years ago, he had an incredibly short attention span. Lying was almost second nature to him; he did it as easily as most of us drink a glass of water. All of those things have turned out to be very similar all throughout his life, and he himself has said, “I’m pretty much the same person at 70 that I was at 7.” I believe that’s true.

But I think that now he has moved to a darker place. He was non-ideological when I knew him. He contributed to candidates from both parties; he was basically a social liberal, and otherwise had no politics. Today, I believe, he has adopted a pretty hard-right set of beliefs. I have reluctantly come to the conclusion that he believes what he says now, and that’s because his base, the people who still love and adore him, are on the far right—and that’s what compels him the most. I think he’s drifted into that more for emotional and psychological reasons than for political and ideological reasons.

What’s really at the heart of this is the fact that he never grew up with a sense that there was anything substantive and meaningful inside him to make him feel okay about himself. Therefore he came to depend throughout his life on external validation. He’s not that different from a lot of us who get very externally focused and struggle with the issue of self-worth. It’s just that his is so much more extreme.

JW: Can you explain why that is?

TS: Obviously I’m not trained as a psychologist, so this comes more from being a journalist and an observer. He had a very brutal childhood. That’s a fact. He had a brutal father who was only interested in toughness and success. I think that, to survive him, Trump felt he had to outdo him, and he had to be not only more successful, but he also had to be tougher and rougher. His mother was essentially absent. And his older brother, in the face of their brutal father, became an alcoholic and died at a very early age. All of that was a message to Trump to always see the world through the lens of win/lose. If you win, you’re okay. If you lose, you’re obliterated. That’s the worldview that has preoccupied him for 70 years.

JW: If the Mueller investigations proceed the way it looks like they’re going to, and more evidence surfaces about the Trump campaign’s collusion with the Russians, and more of Trump’s associates cooperate with the prosecutors, and if Congress maybe move towards impeaching Trump, do you think at that point he might become more cautious, more conciliatory in a defensive mode?

TS: No. Not a chance in hell. It isn’t within his control. He operates most of the time from a survival perspective—particularly when he’s feeling under threat. And he is certainly feeling under threat right now. This is going to get much, much worse for him. This is going to be a really awful time for Trump—and the really bad thing about that, is this: If it’s awful for Trump, he’s not going to keep it to himself. He’s going to inflict it on us. That is very, very worrisome. What he does with North Korea, how he makes decisions in order to deflect attention away from the threat he’s feeling, all of that is something every one of us should be concerned about.