For decades, the librarians of the Vespasian Warner Library in Clinton, Illinois thought the handwriting inside Types of Mankind, published in 1854, belonged to Abraham Lincoln. One of his contemporaries even signed to that effect. Lincoln scholars have now confirmed that the notation was made by the future President.
In the 700-page book, which is available from the OpenLibrary, if anyone wants to go off the deep end, Josiah C. Nott argued that man was created as different races and placed in separate provinces. His theory was that the bible didn't say this was the case because those who wrote the bible only knew about the people in their part of the world, not the other "types of men".
On one of the book's first pages, Lincoln wrote its owner's name, his city and county. Clifton W. Moore was an attorney with whom Lincoln worked in Clinton, who donated thousands of books to the town library upon his death.
It is not known whether Lincoln borrowed the book in 1858 to prepare for his series of debates with Stephen Douglas, or if it was originally borrowed to prepare for the 1855 case of Dungey v. Spencer in which he represented Bill Dungey in a defamation case against his brother-in-law for calling him a "Negro", a designation which would cost him many of his rights. Mr. Dungey prevailed in court, winning $600 in damages.
Though it isn't clear when President Lincoln borrowed the book, the notation from Lawrence Weldon, another Clinton attorney and a friend a of Lincoln, says that he wrote the book's owner's name "just before he left for Washington". Of course this could be a wide timeframe.
It is also consensus that Lincoln borrowed the book to learn how the other side thought.