SS, I see that image as a collective reminder of the thousands of innocent citizens that were wiped out in a split second. As sad and grim as it is, it is still a portrait of our resolve, reach and determination.
The eagle is the symbol of the American Military and power, shedding a tear for the loss of human life on our soil by a deliberate cowardly act of a terrorist. This expresses our consciousness of the event. The eagle also is saying that those responsible will pay !
Yes, this one image pretty well sums up the American conscious.
-----------