On Sept. 20, 1862, Abraham Lincoln had a lot on his mind. The Civil War was raging, and just days later he would issue the preliminary draft of the Emancipation Proclamation.

Still, the weary president found time to sit down to write a testimonial to his podiatrist.

“Dr. Zacharie has, with great dexterity, taken some troublesome corns from my toes,” Lincoln wrote. “He is now treating me, and I believe with success, for what plain people call back-ache. We shall see how it will end.”

This letter is part of an exhibit that opened last Friday at the New York Historical Society