President Barack Obama is putting a symbolic twist on a time-honored tradition, taking the oath of office for his second term with his hand placed not on a single Bible but on two – one owned by Martin Luther King Jr. and one by Abraham Lincoln.

The inclusion of King’s Bible is particularly significant since the inauguration comes on Jan. 21, the federal holiday in honor of the civil rights leader, who delivered his “I Have a Dream” speech 50 years ago at the Lincoln Memorial. Obama will be facing the memorial as he takes the oath. King’s Bible, which his children say he used early in his career as a preacher, has never been part of a presidential inauguration.

The selection of the pair of Bibles announced Thursday is richly symbolic of the struggle for equality in America, beginning with Lincoln’s emancipation of slaves 150 years ago this month, through King’s leadership of the civil rights movement, and ultimately to Obama becoming the nation’s first black president.