It is hard to believe that 10 years have passed since that horrible day when our country was attacked.

The world stopped.

And everything changed.

Certainly, no one can forget where they were or what they were doing when they learned the news: Foreign terrorists had struck America, targeting some of our nation's most visible symbols and killing nearly 3,000 people. The attacks left all of us feeling shaken, vulnerable and afraid. Our tears seemingly would not stop flowing. Our anger knew no limit.

And yet, despite the tragedy, there were signs of hope. America was united, our resolve strengthened by our indivisibility.

As indelible as the images of the Twin Towers falling was the sense of the American people rising. Our hearts ached as we watched New Yorkers comb the smoke- and dust-filled streets for lost loved ones, but they were warmed to watch countless men and women volunteer their time and risk their lives in aid of the search. We prayed for miracles as we watched rescuers tunnel through the debris of Ground Zero, and we gave thanks when we saw an American flag rise above the ruins.

As terrible as the Sept. 11, 2001, attacks were, the one glimmer of hope that emerged came from the knowledge that America could rise above its troubles, simply because it was populated by Americans. Suddenly, we remembered how to be a nation. Not a nation of Democrats and Republicans. Not a nation of liberals and conservatives. Not a nation of various races, faiths, beliefs or any other label that divides us. A nation, period.

Ten years later, we wonder if that lesson has been lost.

As we watch our leaders, in Washington and elsewhere, question the patriotism of their colleagues, simply in an attempt to rustle more votes for one bill or another, we wonder what happened to the notion that despite our differences, we are all Americans.

As we watch the talking heads on television scream insults and hyperbole at one another, simply due to minor disagreements over public policy, we wonder what happened to the idea that, though we may disagree on the method, we assume that everyone has the goal of building a better, stronger country.

As we watch ideologically-driven, though obviously mentally-disturbed, individuals open fire on members of Congress or crash planes into government buildings, we wonder what happened to the unified America.

Our country was delivered a serious challenge in the wake of the terrorist attacks. The success we have had in meeting that challenge is a direct result of our ability to act as one people, willing to respect and embrace our differences, and even gathering strength from them.

Our country faces many challenges today, and we worry that our ability to meet them is being hampered by the inability of some to accept as Americans those who differ with them on the slightest of grounds.

One of the most hopeful images we can recall emerging from Sept. 11, 2001, was when members of both houses of Congress, from both sides of the aisle, gathered that evening on the steps of the Capitol for an impromptu singing of "God Bless America." Unfortunately, given the partisan and ideological divide that exists in this country now, we cannot envision a similar episode occurring today.

Yes, everything changed on Sept. 11, 2001. The question we need to ask ourselves on Sept. 11, 2011, is whether we are going to allow the most positive change to disappear?