First is from the Lord of the Rings, by J.R.R. Tokien(R.I.P.), the passage into the Dwarven Realm of Khazad-dûm(Moria), was guarded by a door with an inscription at the top of the arch that read: "Ennin Durin aran Moria. Pedo mellon a mino" - "The Doors of Durin, Lord of Moria. Speak, friend, and enter."
This phrase is commonly misinterpreted too mean that if one is a friend of the dwarves they would know a special word to open the doors. In fact the inscription means that you should speak the Elvish word for friend 'Mellon' as the word also refers to the Elves themselves who were once friends to the Dwarves and helped to construct the doors.

My second example is from the Wheel of Time series by Robert Jordan(R.I.P.), who makes liberal use of symbolism here.
The Prophecy of the Dragon within the story is notorius for being utterly nonsensical and often having the possibilities of multiple meanings to many passages.
My excerpts are,
"He shall slay his people with the sword of peace, and destroy them with the leaf."
This piece of the prophecy is referring to Rand Al'Thor, who breaks the will of many of the Aiel people(a warrior race from whom he is descended) when he shows them that their ancestors were once pacifists,the 'leaf' refers to 'The Way of the Leaf' a lifestyle held by groups of traveling Tuatha'an (Tinkers). The way preaches complete non-violence and to offer no form(s) of resistance to anything that may happen.
"Fortune rides like the sun on high
with the fox that makes the ravens fly.
Luck his soul, the lightning his eye,
He snatches the moons from out of the sky."
Here the prophecy is mentioning Matrim Cauthon, a man with an unreal amount of luck, and who is comparable to a fox, in cunning and intelligence, despite his laid-back attitude. The raven and the nine moons refer to the woman Tuon, formerly known as the Daughter of the Nine Moons due to her status in the Seanchan Empire. Snatching the moons out of the sky means that Mat will marry Tuon, though he was already aware of this.
"When the Wolf King carries the hammer, thus are the final days known. When the fox marries the raven, and the trumpets of battle are blown."
The Wolf King without a doubt, means Perrin Aybara, due to his ability to talk with wolves, he also carries a blacksmith hammer into battle, and the Seanchan have named him 'Wolf King' for his wolf eyes. The Fox marrying the Raven once again refers to Mat Cauthon, and his matrimony to the Empress Tuon.

Logic Puzzles
Suppose there are two identical twin brothers.
One brother always lies and is completely inaccurate in all of his beliefs, everything that is true he believes false, and everything false he believes to be true.
The other brother always tells the truth and is totally accurate in all of his beliefs.
The interesting thing is that each brother will give the same answer to the same question. For example, suppose you were to ask whether two plus two equals four. The accurate truth teller knows that it is true and will truthfully answer yes. The inaccurate liar will believe that two plus two does not equal four (since he is inaccurate) and will then lie and say that it does.
Now, suppose one were to meet one of the two brothers alone. Would it be possible by asking him any number of yes-no questions to find out which one he is? One logician said, "No, it would not be possible because whatever answers you got to your questions, the other brother would have given the same answers." The second logician claimed that it was possible to find out. The second logician was right.
To determine which brother you are addressing, one question is enough; just ask him if he is the accurate truth teller. If he is, he will know that he is (since he is accurate) and truthfully will answer yes. If he is the inaccurate liar, he will believe that he is the accurate truth teller (since he is inaccurate in his beliefs), but then he will lie and say no. So the accurate truth teller will answer yes and the inaccurate liar no to this question.
Now what was wrong with the first logician's argument; don't the two brothers give the same answer to the same question? They do, but the whole point is that if I ask one person, "Are you the accurate truth teller?" and then ask another, "Are you the accurate truth teller?" I am really asking two different questions since the identical word you has a different reference in each case.
Don't worry, this one gives alot of people headaches, took me several hours to understand it, even when I already knew the answer. Never try to force your reader to answer a question however, make him think about it sure, but if it's anything of the above caliber, I wouldn't try to make them wait too long.