In Alice in Wonderland, Lewis Carrol writes:
"Then you should say what you mean." the March Hare went on.
"I do," Alice hastily replied; "at least -- at least I mean what I say -- that's the same thing, you know."
"Not the same thing a bit!" said the Hatter, "Why, you might just as well say that 'I see what I eat' is the same thing as 'I eat what I see'!"
It's an alimentary course in logic.