What have we learned?

That people are willing to give up freedom for the illusion of security. [Link]

Today is September 11th, 2013.

Twelve years ago today, a cell of angry, highly committed, and (by the standards of their peers) extremely well trained young men executed the simultaneous hijacking of four airliners, and used them to mount a suicide attack on those they perceived as their enemies.

What have we learned from this?