Security is both a feeling and a reality, and they're different. You can feel secure even though you're not, and you can be secure even though you don't feel it. There are two different concepts mapped onto the same word — the English language isn't working very well for us here — and it can be hard to know which one we're talking about when we use the word.

http://www.wired.com/politics/security/commentary/securitymatters/2008/04/securitymatters_0403

Urs