Dumbledore Socks Mystery, Mirror of Erised

'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, woolen socks.' Harry stared.

'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.'

The Mirror of Erised - Pg 230