If you're doing research on Abraham Lincoln, this book would be a secondary source because Wills offers his thoughts on Lincoln and the Gettysburg Address. Abraham Lincoln's letters, speeches, or memoirs, for example, would constitute primary sources. Wills was one of Lincoln's contemporaries. He was an attorney who lived in Springfield, Illinois when Lincoln was serving as president of the United States. In 1866, Wills published "Abraham Lincoln: A Study in Humor," which is considered a critical assessment of Lincoln. This book has been called "a masterpiece of comic genius" by one scholar. Lincoln is known for having delivered the Gettysburg Address on November 19, 1863. But before he was assassinated in 1865, Lincoln was losing hope that the Civil War could be ended without destroying America's democratic form of government. So in order to keep morale high among his fellow soldiers and the people back home, Lincoln made some jokes about the war and its cause slavery. These jokes are contained in a book called "The Wit and Wisdom of Abraham Lincoln." Lincoln told many stories during his time in office. One story that keeps coming up during school presentations is "A Christmas Story," which tells how Lincoln saved a young soldier from execution. Another favorite story of children at holiday times is "The Night Before Christmas," which features Santa Claus.