thinking, the mind, insanity

"I know what you're thinking about," said Tweedledum, "but it isn't so, no how." Contrariwise," continued Tweedledee, "if it was so, it might be; and if it were so, it would be; but as it isn't so, it aint. That's logic."

"Thinking again?" the Duchess asked. "I've a right to think," said Alice sharply.

"She'll be feverish after so much thinking."

"She means well but she can't help saying foolish things, as a general rule."

"She's in that state of mind."

"Oh, you can't help that," said the Cat; "we're all mad here. I'm mad. You're mad." "How do you know I'm mad?" said Alice. "You must be," said the Cat, "or you wouldn't have come here."