Everything which is not forbidden is allowed

Okay, imagine you are playing a game with your friends. You make some rules, like "you can't hit the ball with your hand." That means it's not allowed. But for everything else, if you don't say it's not allowed, that means it's okay to do. So if you want to kick the ball or hit it with a stick, that's okay because you didn't say, "you can't kick the ball or hit it with a stick." It's like when your parents tell you, "you can't eat cookies before dinner," that means you are not allowed to do it. But if they don't say, "you can't drink water before dinner," that means it's okay to do. The same idea applies here - everything that is not forbidden is allowed.