SPRINGFIELD, Ill. (AP) — Historical experts say they’ve found Abraham Lincoln’s handwriting inside a tattered book justifying racism that he may have read to better understand his opponents’ thinking on slavery.

“Types of Mankind” was published in 1854 and circulated for decades by the Vespasian Warner Public Library in Clinton. Director Joan Rhoades brought the 700-page book to the Abraham Lincoln Presidential Library and Museum in May to determine whether an inscription inside was made by the former president who worked to free the country’s slaves through the Emancipation Proclamation.

Library and Museum Curator James Cornelius says Lincoln likely read the book to help prepare him to rebut pro-slavery arguments. He says he could immediately tell the book’s inscription was authentic by the way certain letters were formed.

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