Because it's perfect, that's why. ok I don't ship Johnlock but this is epic. <-- I'm not gonna take this as Johnlock but instead as uncle John reading to Sherlocks and Molly's son Hamish<<how can you not ship Johnlock? This is Johnlock!
Oh I love her so much. I really hope that this is the season when the Doctor suddenly says " Oi! I just figured out how to let Donna Noble remember everything without killing her!" :)<<<<< that last bit would make me the happiest Whovian around