Something I've been wondering about regarding the Four Guards scene in Labyrinth is how Sarah determines which one is telling the truth. She asks one of them, "would he say that this one leads to the castle", to which the other one says yes. When the other one points out that the other one could be lying or he could be lying, Sarah reasons that neither would be lying. But she never asked the other one the same question. If she asked the other guard what she had just asked, he could have given a different answer (maybe she should have asked the other guard what she just asked... Uh, the other guard), since he always lies. Of course, either the one who always tells the truth is the one who told her that one of them always tells the truth and one always lies, or they are both liars. Though she does end up going through that one's door. Though I think the other one tells the truth about something at one point as well (the fact that he could be lying or he could be lying). The bottom two guards don't know which door leads to the castle, but Sarah could have asked them if they know which one is the truthful one. And if one always lies, couldn't she have asked an obvious question (like if she's a girl, or if they are guarding doors) and see which one lies? Then again, in the last few years I've been confused about whether lying is just a rule, and after watching the movie recently, I've noticed that they mention in the rules that she can only ask one of them. They say it's in the rules, in between telling her that only one can be asked and that one always lies. As a kid, I thought that one of the doors lead to "sudden death" instead of "certain death", and thought she went through the death door (since she falls into a pile of hands). But then I realized that she did get out and to the castle... But now I wonder if she only got out because Hoggle helped her (as she would have probably died otherwise). But yeah, to the original question, how did Sarah figure it out just by asking "would that one say that this one leads to certain death?"