Doctor: I’m not just a professional, I’m the Doctor. 

Alex: What’s that supposed to mean?

Doctor: It means I’ve come a long way to get here, Alex, a very long way. George sent a message, a distress call if you like. Whatever is inside that cupboard is so terrible, so powerful that it amplified the fears of an ordinary little boy across all the barriers of time and space; through crimson stars and silent stars and tumbling nebulas like oceans set on fire, through empires of glass and civilizations of pure thought and whole, terrible, wonderful universe full of impossibilities. You see these eyes? They’re old eyes. And one thing I can tell you Alex…monsters are real.