‘The mirror will be moved to a new home tomorrow, Harry, and I ask you not to go looking for it again. If you ever do run across it, you will now be prepared. It does not do to dwell on dreams and forget to live, remember that. Now, why don’t you put that admirable cloak back on and go back to bed?’
Harry stood up.
‘Sir - Professor Dumbledore? Can I ask you something?’
'Obviously, you've just done so,' Dumbledore smiled. 'You may ask me one more thing, however.'
'What do you see when you look in the mirror?'
'I? I see myself holding a pair of thick, woollen socks.'
‘One can never have enough socks.’ Said Dumbledore. ‘Another Christmas has come and gone and I didn’t get a single pair. People will insist on giving me books.’
It was only when he was back in bed that it struck Harry that Dumbledore might not have been quite truthful. But then, he thought, as he shoved Scabbers off his pillow, it had been quite an impertinent question.
Harry Potter and the Philosopher’s Stone by J.K. Rowling