Think New Figure 2
A riddle: Once there was an evil spam email distribution mogul named Cretino. He was captured by a gang of enraged email correspondents who placed him in a reinforced steel room with just two doors: no windows. They tortured him for a while with soft elevator music. Then they posed a simple challenge to the evil spammer. [ If you can up with the answer to a riddle, we will set you free. If you can’t you must suffer your punishment. ] Unable to sithstand the musical onlsaught and whatever might come next, Cretino agreed.

He was told that one of the doors led to certain freedom while the other door led to certain punishment, which would consist of teaching cranky ludites how to filter spam emails, eight hours a day for 5 years. Each door was guarded by an armed spam hater. He could ask only one question to only one of the guards that would ensure his freedom. Oh, and as part of the deal, one of the guards would certainly lie when asked the question, while the other would certainly tell the truth. Our antihero was not told which guard or which door was which. What is the one question Cretino needed to ask?

Answer: What would the OTHER guard say if I asked her which is the door to certain freedom? So if he asked, by chance, the lying guard, that guard would lie about what the truth-telling guard would say. If he asked the truth-telling guard, that guard would tell the truth about the lie the lying guard would tell. So either way he could do the opposite of what the guard said and he would be free! (Unfortunatley for Cretino, he was thinking OLD and is still out there serving the ludite community.)