In the last few hours before the tenth anniversary of the September 11 attacks, Bill Clinton spoke at a dedication ceremony for the Flight 93 memorial in Shanksville, Pennsylvania. He shared the podium with his successor, George W. Bush who did the same on Sunday, speaking briefly after Barack Obama's address at the 9/11 Memorial at Ground Zero. Each speech showed a different side of the respective presidents. Bill Clinton spoke with his characteristically empathetic, measured cadence, and he sounded older than we remember. George W. Bush spoke over the sound of scattered applause in that familiar Texas drawl. Barack Obama, through the bulletproof glass that separated him from the crowd, read a psalm at Ground Zero. Before the end of the day he'll lay a wreath at the memorial sites in Shanksville and at the Pentagon.

Watching all of the addresses is like taking a trip back in time. We remember a more prosperous, more innocent America when we hear President Clinton speak. When President Bush speaks, we're reminded of the tumultuous decade that followed, not only the attacks but the wars that followed and the test of the nation's will. President Obama leaves us with a bit more to think about--a future that he's promised to lead us to--and Sunday night he'll give a longer speech at a "Concert of Hope" at the Kennedy Center, one that will carry a deeper message about the enduring American spirit. Each in their own ways, that seems to be the message of all the speeches.

Bill Clinton speaks on September 10, 2011 in Shanksville, Pennsylvania

George W. Bush speaks after Clinton in Shanksville.

Presidents Bush and Obama's brief remarks at Ground Zero on September 11, 2011.

Paul Simon (not a president) sings "Sound of Silence" at Ground Zero on September 11, 2011.

President Obama at the Pentagon.

And finally, President Obama's address at "A Concert for Hope" at the Kennedy Center in Washington.