"You can still be a teacher. Just ... not in exactly the same way. There are people here who could learn from you. People here who would love to join you in the library to discuss all sorts of scholarly things. It's even possible that Joan might find her way here. I'm not saying that she will, but the TARDIS does seem to be selecting quite a few passengers from my--our lives." The Doctor was desperate to try to bring John some comfort. He hated to see the man in so much pain, especially after the sacrifice John had been forced to make. "Believe me, I know what it's like to have your home torn away. I know. I know what it's like to lose the things you know and love and have to rebuild. It can be done. It can."