The more familiar public swearing in will take place tomorrow. Historically, when January 20, the day mandated by the Constitution that begins the presidential term, falls on a Sunday, there have been two ceremonies.
Formally embarking on a second term, Vice President Joe Biden took the oath of office Sunday, surrounded by family and friends in an early morning ceremony that kicked off a day of celebrations marking four more years for the Obama administration.
President Barack Obama was to be sworn in just before noon at the White House, 24 hours before re-enacting the ceremony before an expected crowd of hundreds of thousands gathered at the Capitol and across the National Mall.
Biden, following a private Mass, was sworn in at the Naval Observatory. Justice Sonia Sotomayor, appointed by Obama as the first Hispanic on the Supreme Court, administered the oath of office to Biden, who placed his hand on a Bible his family has used since 1893.
"I will support and defend the Constitution of the United states," Biden said as he recited the oath.
Among the 120 guests on hand to witness the vice president's second swearing-in were Attorney General Eric Holder, departing Interior Secretary Ken Salazar and several Democratic lawmakers.
Sunday's subdued swearing-in ceremonies are a function of the calendar and the Constitution, which says presidents automatically begin their new terms at noon on Jan. 20. Because that date fell this year on a Sunday - a day on which inaugural ceremonies historically are not held - organizers scheduled a second, public swearing-in for Monday.
A crowd of up to 800,000 people is expected to gather on the National Mall to witness that event, which will take place on the Capitol's red, white and blue bunting-draped west front. Supreme Court Chief Justice John Roberts, who famously flubbed the oath of office that Obama took in 2009, was to swear the president in both days.
Americans rarely show much enthusiasm or interest in civic extravaganzas. But inauguration day is an exception. The utterly peaceful transfer of power against a backdrop of majesty and solemnity - spiced up with a parade and inaugural balls of frivolity and fun - is a truly American invention and part of what makes us exceptional.
Even though the man taking the oath might not have been your choice for president, this demonstration of American democracy should be celebrated by all.