It is a key part of every U.S. president's swearing in -- the Bible that he places his hand on when taking the oath of office.
"I think the monumentality of the moment has been confused with the size of the bible," Mark Dimunation, chief of rare the rare books collection at the U.S. Library of Congress says. "It's actually a small family Bible."
On March 4, 1861, the president who freed the slaves, Abraham Lincoln, put his hand on the Bible and swore to uphold the Constitution.
151 years later, President Barack Obama will use that same Bible when he's sworn in for his second term.
"There is this incredible moment when Lincoln walks on stage, and as reports have it the clouds part and he gives this magnificent inaugural address and uses the bible to swear in at a moment when the country is incredibly divided," Dimunation says.
Lincoln didn't have his family Bible with him, so he borrowed one from William Thomas Carroll, the Clerk of the Supreme Court.
A seal in the back of the Bible attests that it was used in the Lincoln inauguration.
The man administering the oath of office was Chief Justice Roger Taney, who did not share Lincoln's views on slavery.
"You can imagine the tension that was probably palpable between the two of them," Dimunation says. "Taney was the justice that cast the deciding vote that put through the Dred Scott decision. In essence, pushing slavery forward for many more years."
President Obama used the Lincoln inauguration Bible the first time he took the oath of office in 2009. He will be sworn into his second term by Supreme Court Chief Justice John Roberts on Monday, Jan. 21 in Washington D.C.
After a slew of daytime events, including Obama's inaugural address and a parade, the President and First Lady Michelle Obama will attend two inaugural balls.