Interesting quote from Thomas Friedman's book "Longitudes and Attitudes." "If it is possible to recruit nineteen educated young men to hijack four planes and commit suicide by flying them into the Pentagon and the World Trade Center, and thereby kill close to three thousand totally innocent people who kissed their spouses good bye that morning and a few hours later were phoning home to their loved ones (if they were lucky) and telling them they were about to die, then anything is possible. Whatever civilizational restraints on human behavior you thought existed before are no longer there. An important wall has been blown away. "