Sept 11, 2001 was a sad day. On that day many regular citizens were killed in four coordinated terrorist attacks.
To prevent such future tragedies, we need Unity.
From the 9-11 Commission Final Report:
"We call on the American people to remember how we all felt on 9/11, to remember not only the unspeakable horror but how we came together as a nation—one nation. Unity of purpose and unity of effort are the way we will defeat this enemy and make America safer for our children and grandchildren."
Lincoln said "United we stand, divided we fall." At that time he spoke of just one nation.
Today unity just in our nation is not enough. We as a world must follow this same mantra if we, humankind, are to ultimately survive.
I highly recommend that every US Citizen read and re-read the full 9-11 report. It has many lessons for all of us. It can be found at: http://www.gpoaccess.gov/911/Index.html