Vizzini: But it's so simple. All I have to do is divine it from what I know of you. Are you the sort of man who would put the poison into his own goblet or his enemies? Now, a clever man would put the poison into his own goblet because he would know that only a great fool would reach for what he was given. I am not a great fool so I can clearly not choose the wine in front of you ... But you must have known I was not a great fool; you would have counted on it, so I can clearly not choose the wine in front of me.
[The Princess Bride, Scene V]