In the middle of the climactic episode of J. K. Rowling's children's novel Harry Potter and the Sorcerer's Stone, Harry Potter and Hermione Granger find themselves in a room whose two exits are blocked by raging flames.
On a table in the room stand seven bottles, along with a piece of paper inscribed with the following verses:
Danger lies before you, while safety lies behind,
First, however slyly the poison tries to hide
Two of us will help you, whichever you would find,
One among us seven will let you move ahead,
Another will transport the drinker back instead,
Two among our number hold only nettle wine,
Three of us are killers, waiting hidden in line.
Choose, unless you wish to stay here forevermore,
To help you in your choice, we give you these clues four:
You will always find some on nettle wine's left side;
Second, different are those who stand at either end,
But if you would move onward, neither is your friend;
Third, as you see clearly, all are different size,
Neither dwarf nor giant holds death in their insides;
Fourth, the second left and second on the right
Are twins once you taste them, though different at first sight.
(Rowling 1998, p. 285)
Hermione, who is an exceptionally avid student, realizes that she can use reasoning to determine the bottles that they need to escape from the room. As she says, "This isn't magic-it's logic-a puzzle. A lot of the greatest wizards haven't got an ounce of logic, they'd be stuck in here forever." Hermione thinks hard, and in a few minutes she is able to identify the bottles that allow escape. She goes back to sound the alarm, and Harry goes forward to confront the evil-doer.
Can you figure out the contents of each of the seven bottles below,
just as Hermione did?
