In the original Lewis Carroll story, Alice's Adventures in Wonderland, the Mad Hatter famously asks Alice, "Why is a raven like a writing-desk?" 
"Have you guessed the riddle yet?" the Hatter said, turning to Alice again.
"No, I give 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 wasting it in asking riddles that have no answers."
When Lewis Carroll was pressed about the answer to the riddle, he added his own answer to an 1896 edition of Alice:
Enquiries have been so often addressed to me, as to whether any answer to the Hatter's Riddle can be imagined, that I may as well put on record here what seems to me to be a fairly appropriate answer, viz: "Because it can produce a few notes, tho they are very flat; and it is never put with the wrong end in the front!" This, however, is merely an afterthought; the Riddle, as originally invented, had no answer at all.
- Because the notes for which they are noted are not noted for being musical notes.
Because Poe wrote on both.
Because there is a B in both and an N in neither. (suggested by Aldous Huxley)
Because it slopes with a flap.
Because without them both Brave New World could not have been written.
Because one has flapping fits and the other fitting flaps.
Because one is good for writing books and the other better for biting rooks.
Because a writing-desk is a rest for pens and a raven is a pest for wrens.
Because "raven" contains five letters, which you might equally expect to find in a writing desk.
Because they are both used in cari-on decomposition.
Because they both tend to present unkind bills.
Because they both have a flap in oak.
Because it bodes ill for owed bills.
Because they each contain a river--Neva and Esk.
Because they both come with inky quills.
Because Poe wrote on both.
Because you cannot ride either of them with a bicycle.
Because neither is made from aluminum.
Really. Who cares? Carroll plainly admits he didn't intend there to be an answer. 
It was part of the ramblings of a madman. Granted, the Mad Hatter was more in touch with truths about human nature than initially seems, but his purpose is to confound both Alice and the reader until we find unexpected truths from within ourselves.
Do our own riddles always have to have answers? Can we have lingering questions about ourselves that we never seem to rectify? Maybe those questions are the ones that drive us forward, drive us on, as we search for our own unexpected truths.
Getting from point A to point ME often involves a great deal of soul-searching, of contemplating our own riddles. And then, just when you think you've gotten the answer, the riddle shifts and changes and morphs, just enough that you can't quite see it so clearly any more, like looking directly at a dim star. Sometimes you have to examine the Riddle of You out of the corner of your eye to get the best view.
Even then, there may not be an answer. Other people will certainly try to answer it for you, and you may even have to make something up to pacify the others, to make them stop asking. You may find an answer that pacifies you, at least for a while, until you discover another answer that's better suited to your moment.
It doesn't matter, so long as you're thinking and contemplating and looking. It's the beauty and the complication of the riddle itself that's important. It doesn't matter if you're not noted for being musical notes or if you come with inky quills; just keep thinking about why your raven is like a writing-desk, even if you haven't the slightest idea.
