Russell H. Conwell 
Why Lincoln Laughed [PDF ebook] 

Though he would later achieve widespread acclaim as a popular minister and writer, when he was a young man serving in the Union army, Russell Conwell had a chance encounter with then-President Lincoln. Over the course of their conversation, Conwell was able to gain a great deal of insight into Lincoln’s unique personality and sense of humor. His recollections of their chat are presented in this charming volume.