I think Spider-Man says "with great power comes great responsibility." As a kid, I was a huge Spider-Man fan, and still believe that he's right. :D

Yes, freedom should be defined very well. I take the libertarian position that freedom comes from and is limited to self-ownership. You are free to do with your body and the fruits of your labour as you please. To kill someone is to take away another person's body, and is therefore an infringement to someone's self-ownership.