Alive isn't sad
Idris: Doctor. Are you there? It's so very dark in here.
The Doctor: I'm here.
Idris: I've been looking for a word. A big, complicated word but so sad. I've found it now.
The Doctor: What word?
Idris: "Alive." I'm alive.
The Doctor: Alive isn't sad.
Idris: It's sad when it's over. I'll always be here. But this is when we talked. And now, even that has come to an end. There's something I didn't get to say to you.
The Doctor: Goodbye.
Idris: No. I just wanted to say... hello. Hello, Doctor.