Today is Abraham Lincoln's birthday. Above is my favorite picture of him. It is called the Cracked glass portrait of Lincoln, was taken on April 10th 1865 and is considered the last known picture of Lincoln before his death.
I once read that while Lincoln was sitting for the picture the photographer Alexander Gardner had some problems with his equipment. As Gardner fiddled with his camera Lincoln sunk deeply into thought. As a result, it is the closest you'll get to a candid in 19th century photographic portraiture. The melancholy etched on Lincoln's face is unbearably sad.