First, however slyly the poison tries to hide 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 the second on the right Are twins once you taste them, though different at first sight.

Hermione let out a great sigh and Harry, amazed, saw that she was smiling, the very last thing he felt like doing.

"Brilliant," said Hermione. "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."

"But so will we, won't we?"

"Of course not," said Hermione. "Everything we need is here on this paper. Seven bottles: three are poison; two are wine; one will get us safely through the black fire, and one will get us back through the purple."

"But how do we know which to drink?"

"Give me a minute."