From William Lee Miller’s excellent review of Lincoln’s Melancholy: How Depression Challenged a President and Fueled His Greatness by Joshua Wolf Shenk:
In 1998, Shenk (a young essayist who frankly mentions his own battles with depression) read a reference to Lincoln’s melancholy in an essay on suicide and set about learning more. In his researcher’s zeal, he read Lincoln scholars and also sought them out and interviewed them; he went to Lincoln’s birthplace and Ford’s Theater, stood where Lincoln delivered the “house divided” speech, held in his hand Lincoln’s letters to his friend Joshua Speed, saw the fatal assassin’s bullet and, since heredity is one ingredient inclining a person to depression, obtained the records admitting Mary Jane Lincoln, Lincoln’s father’s cousin, to the Illinois Hospital for the Insane in 1867. He even attended a convention of Lincoln impersonators, borrowed a Lincoln suit for himself and joined in. His book has page after page of acknowledgments, to the point that one may be tempted to say: No wonder a writer with this many friends could produce such a strong book.
“The goal,” Shenk writes, “has been to see what we can learn about Lincoln by looking at him through the lens of his melancholy, and to see what we can learn about melancholy by looking at it in light of Lincoln’s experience.” He has effectively cast light in both directions.