Some interesting thoughts on Power and Vulnerability by Lew Rockwell:

The small, unintrusive government faces few threats to its limited power. Until Lincoln’s day, for example, it was possible to walk around Washington unencumbered. One could knock on the White House door and be greeted by the president’s butler. No office was closed to citizens. It was like any other town. There was no great fear emanating from the presidential quarters or any other public office. Why? Because power in the modern sense was so small. No one in government had good reason to feel threatened by anyone.

But as the power of DC has grown, so has its fortress mentality.

And these days every Federal building is a fortress.

According to this meme, we can determine the amount of power an group wields by how secure it feels, as shown by the inverse of its security apparatus. Powerful organizations buy lots of "security", because they feel little.

It's worth examining America's rush to trade a little bit of liberty for security, in the wake of 9/11, in that light.