How did you get the idea for this book?

I was looking for a topic in mental illness, something I could dig into for a long magazine piece or a book. I was also struggling with depression myself. So I was doing some reading that doubled as research and personal exploration. One night I came home and flopped down on my bed with a book — a literary anthology of writings on suicide.   There was an essay in it by Howard Kushner — an excerpt, actually, from a book of his called Self Destruction in the Promised Land . The piece talks about two historical figures: Meriwether Lewis (of Lewis and Clark), who almost certainly killed himself, and Abraham Lincoln, who came close but never did. This was the first I’d ever heard of Lincoln’s depression. I found it amazing. It was instantly recognizable but also totally mysterious. I had all kinds of questions, and the biggest one was how come I hadn’t heard of this before. I went around to Lincoln scholars and asked: Has there ever been a book on Lincoln’s melancholy? It turned out there hadn’t been.

What did you hope to learn from his depression?

I had two goals for this book. I wanted to see what we could learn about Lincoln by looking at him through the lens of his depression. I also wanted to see what we could learn about this thing we call depression by looking at it through the lens of Lincoln’s story.

Did Lincoln have clinical depression?

Yes, in the sense that modern clinicians who look the facts of his case say — as they’ve said to me — “If this guy showed up in my waiting room and gave me this history, I’d want to treat him.” Also, Lincoln meets the criteria for major depression, and for major depressive disorder. This is a guy who had two major breakdowns as a young man. In both instances, he was talking about killing himself — and his friends took him seriously enough that they took active measures to keep him safe. But I believe that diagnosis is the beginning, not the end of the story. It’s a way for us to see how seriously troubled Lincoln was, but then we have to ask: How did he conceptualize his suffering? What language did he use? And, of course, what did he do about it?

It seems like the topic of Lincoln’s depression would be awfully hard to research. How did you go about it?

The first and most important project was to gather up all the significant primary evidence on Lincoln’s depression. That means everything he said — and everything that anyone who knew him said — about his temperament, his moods, his breakdowns, his philosophy, his coping strategies, etc. I basically spent three or four years in libraries, going through card catalogues, combing through archive boxes, and filling suitcases with books and photocopies to take home. Everybody who knew Lincoln well had something to say about his depression. So a lot of the work was going through these reminiscences and memoirs with an eye out for this kind of material. And I put everything I found on a timeline. (This was pretty straightforward for things like dated letters, and a bit trickier for reminiscences, where I had to ask, “How and when did this person know Lincoln? What part of Lincoln’s life is this referring to?”) When I got it plotted out, I could see the movement of his melancholy against the movement of the rest of his life, and I started to see the outline of a story. The big picture is that, over his whole life, we can see how Lincoln first recognized and articulated his mental trouble; second, he found a way to survive it, deal with it and sometimes distract himself from it; and, finally, that he found ways to make his temperament and his moods work for him.

From there I was off chasing down all kinds of material to help me really understand the story and how to tell it. I had to get to know all kinds of characters in Lincoln’s life — like his friend Joshua Speed, his disastrous love interest Matilda Edwards, and his doctor Anson Henry. I had to get to know the psychology of the time, which meant studying medicine, religion, philosophy, popular culture, and so on. And I was also constantly reading in today’s literature trying to understand topics like humor and its relationship to depression, the nature of suicidal thinking, the relationship between depression and creativity, and so on.

How did Lincoln’s depression fuel his greatness?

First of all, in dealing with his depression head on — addressing it, staring it in the eye, grappling with it, and getting a hold of it within himself — Lincoln did work that turned out to be enormously character building and valuable to him. In one sense, the muscles he developed over a lifetime of suffering prepared him for the challenges that he faced in his presidency. Second, he had a tendency to see the dark truths of a situation, and he drew on this powerfully in his rhetoric and his actions. Experiments have shown that people who suffer from depression also exhibit something called “depressive realism” — and this applies to Lincoln. Finally, the depths of emotion that he explored as a result of his depression contributed to a deep creative capacity — as a writer and thinker. In his first inaugural address, he urged that the country would be well again when touched by “the better angels of our nature.” He didn’t say that that the worse angels would be killed or that they would go away. To the contrary, the image suggests that selves, and nations, are multi-faceted, capable of better and prone to worse, and locked in a struggle. It’s justifiably a famous phrase, and it reaches deep into the psyche because it reflects an experience that every human being knows intuitively, one of division and conflict, broken-ness and harmony, suffering and reward. These were ideas that Lincoln lived and struggled with much of his life.