Why Is A Raven Like A Writing Desk?

"You should learn not to make personal remarks," Alice said with some severity. "It's very rude."
The Hatter opened his eyes very wide on hearing this; but all he said was, "Why is a raven like a writing desk?"
"Come, we shall have some fun now!" thought Alice. "I'm glad they've begun asking riddles. I believe I can guess that," she added aloud.
"Do you mean that you think you can find out the answer to it?" said the March Hare.
"Exactly so," said Alice.
"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. "You might just as well say that 'I see what I eat' is the same thing as 'I eat what I see'!"
"You might just as well say," added the March Hare, "that 'I like what I get' is the same thing as 'I get what I like'!"
"You might just as well say," added the Dormouse, who seemed to be talking in his sleep, "that 'I breathe when I sleep' is the same thing as 'I sleep when I breathe'!"
"It is the same thing with you," said the Hatter, and here the conversation dropped, and the party sat silent for a minute, while Alice thought over all she could remember about ravens and writing desks, which wasn't much.
--Lewis Carroll (1832--1898)
(from "Alice's Adventures In Wonderland ")

Elvis sighting (top)
south rim from above Unkar Rapid (middle)
Sumner Butte (below)