Body Language

I've always wondered whether we can know how people are thinking without talking to them. From about one month I heard about body language, so I decided I should read whats that about. It's so interesting to understand people's mood without even talking to them. By reading body language you can also know whether someone is telling the truth or not. It shows if someone is interested in what you're saying or not. If you are standing with your friends, you can tell if they're happy being with you or they just want to end this conversation. For example if you're standing with people and you find one of them crossing their hand, then they maybe not interested in what you're saying or it's just a habit. On the other hand, if they are interested in what you're saying then their pupil will get larger. I tried many things like this with my friends and it really worked!! I read about even more things about body language that is really cool. I think you should do too. Here is a link: http://en.wikipedia.org/wiki/Body_language