Do you know why is a raven like a writing-desk?

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.'
<…>
`Have you guessed the riddle yet?' the Hatter said, turning to Alice again.
`No, I give it up,' Alice replied: `what's the answer?'
`I haven't the slightest idea,' said the Hatter.
`Nor I,' said the March Hare.
Alice sighed wearily. `I think you might do something better with the time,' she said, `than waste it in asking riddles that have no answers.'
Lewis Carroll. Alice's Adventures in Wonderland


Alice does not know “Why is a raven like a writing-desk”. What about you?