River’s narration: [as the Doctor walks away from the Library] When you run with the Doctor, it feels like it’ll never end, but however hard you try you can’t run forever. Everybody knows that everybody dies and nobody knows it like the Doctor, but I do think that all the skies of all the worlds might just turn dark if he ever, for one moment, accepts it.
River’s narration: Everybody knows that everybody dies, but not every day. Not today. [The Doctor uploads her into CAL, where she is “saved” in a virtual reality, along with her fellow expiditioners killed by the Vashta Nerada] Some days are special. Some days are so, so blessed. Some days, nobody dies at all. Now and then, every once in a very long while, every day in a million days, when the wind stands fair and the Doctor comes to call, everybody lives.
— River Song, Silence in the Library